While the data as presented are hard to interpret in terms of detailed energy balance because daily energy intake and expenditure is not reported, as it should have been, the subjects claimed to be doing more exercise and eating less but only lost 10 pounds in two years. The prescribed diets contained 1800kcal for men and 1500kcal for women. These values are close to the basal metabolic rates of these mostly obese people. They should have lost weight continuously and markedly during the trial. Let's see how much they should have lost if they were reporting accurately. They claimed to be eating about 500 kcal less than baseline per day on all diets. Even doing the same amount of exercise they should have lost about a pound per week (one pound of fat is about 3500 kcal) or about 50 pounds per year or 100 pounds in 2 years. Since they claimed to be doing more exercise they should have lost even more. If they had been telling the truth, most participants should have starved to death well before the end of the study! Ergo, most overweight and obese people lie about food intake and exercise; they tell investigators what the investigators want to hear.

Obesity is and always has been caused by food addiction. Until we deal with that, the pandemic of obesity and its terrible consequences will only worsen. Unlike most infectious diseases, there is no vaccine against  addictions. We all must make the right choices as to what we put into our bodies. In developed capitalist democracies this is the hardest task we have. And how to deal with it is not taught in medical school.

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That obese people lie about food intake was proven beyond doubt by a study using doubly-labeled water to measure true energy expenditure. About 65% of these subjects were overweight or obese. They claimed to be eating only about 1500 kcal/day, about 40% less than they actually ate, but were burning 2500. So, they should have had a deficit of 1000 kcal/day and be losing weight dramatically but their weights were stable. Ergo they were "misreporting", a euphemism for lying.

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I recently started using the Pyramid Tracker at http://www.mypyramidtracker.gov/default.htm to assess the quality and quantity of my food intake, and my physical activity.  The Food Calories/Energy Balance feature calculates my energy balance taking my food/energy/calories intake and subtracting the energy I expend from physical activity for the day.  It also gives me a snapshot of my weekly, monthly and yearly statistics and my nutrition and physical activity progress (sometimes good and sometimes not so good).

Do you think MyPyramidTracker is practical?  Do you like it?

"Mac"

The Passive House Planning Package (PHPP)
is a clearly structured design tool that can be used directly by architects and designers.
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This was indeed the case for the first Passive Houses that were completed in 1991. Calculating the energy balance of buildings with very low energy consumption is a demanding task - existing regulations, standards and prestandards lack the required precision. Nevertheless, we have identified the critical factors for preparing reliable balances - with tools that are simple to use and with acceptable effort in terms of data input.
(from the Passivhaus Institut: http://www.passiv.de/07_eng/phpp/PHPP2007.htm,
find sources to order an English version at the bottom of the page,
find a free simplified version here, in German only)

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The equations representing energy balance may be compiled for various volumes and surfaces of atmosphere, hydrosphere and lithosphere. However, in the studies of global environment, equations are often employed for an imaginary column whose upper end is at the upper boundary of atmosphere and which passes through atmosphere deep below Earth’s surface. Three equations of energy (heat) balance describing global energy balance are:

(a) Energy balance equation of Earth’s surface

(b) Energy balance equation of Earth-atmosphere system

(c) Energy balance equation of atmosphere.

(a) Energy balance equation of Earth’ surface

Major elements of this equation are (Fig. 1):

(i) Radiation balance (R) i.e. radiation flux, which is considered positive in value when it describes inflow of energy (heat) from above to underlying Earth’s surface.

(ii) Turbulent energy (heat) flow (P) from underlying Earth’s surface to atmosphere.

(iii) Underground energy (heat) flow (A) from Earth’s surface to deeper layers of hydrosphere or lithosphere.

(iv) Energy (heat) expenditure on evaporation (or release of heat in condensation) (LE) where L is latent heat of vaporization and E is rate of evaporation.

With the above elements, energy balance equation of Earth’s surface is given as:

R = LE + P + A
The elements of energy balance not included in the above equation are:

(i) Energy expenditure on melting of ice or snow on surface (or inflow of heat from freezing of water)

(ii) Energy expenditure associated with friction of air currents, ocean waves produced by winds and ocean tides

Figure-1. Components of the energy balance of Earth-Atmosphere-Hydro-Lithosphere system.

(iii) Energy (heat) flows transferred by precipitation whenever their temperature is not equal to that of underlying surface

(iv) Energy expenditure on photosynthesis

(v) Energy (heat) inflow from oxidation of biomass.

With the addition of these elements also, comprehensive energy balance equation of Earth’s surface may be obtained.

The magnitude of underground energy (heat) flow (A) may be obtained from the energy balance equation of a vertical column whose upper base is at Earth’s surface and lower base at the depth below ground surface where heat flow is negligible (Fig. 2). Since heat flow from depths of Earth’s crust is negligible, vertical flow of heat at the lower base of column may be assumed to be zero. The equation for A is given as:

A = Fo + B

where, B represents the changes in heat content inside the column over a given period of time and Fo is the inflow of heat produced by horizontal heat exchange between the column being considered and the surrounding space of hydrosphere or lithosphere. Fo is equal to the difference between amounts of heat entering and leaving through vertical walls of column.

In lithosphere, Fo usually becomes negligible due to low heat conductivity of soil. Thus for land A = B and since over a period of whole year, upper layers of soil are neither heated nor cooled, A = B = 0.

Fo becomes large in case of water bodies having currents with a large horizontal heat conductivity determined by macroturbulence. In case of closed water bodies taken as a whole whose depth and area are large, values of A and B are close. It is because heat exchange between such bodies of water and the ground are usually negligible. However, in specific sectors of oceans, seas and lakes, magnitudes of A and B may be substantially different. The average yearly value of heat exchange of an active surface with lower is not zero but is equal to the quantity of heat received or lost due to currents and macroturbulence i.e. A = Fo.

Thus for average yearly period, energy balance equation of Earth’s surface will be:

(i) For land: R = LE + P

(ii) For ocean: R = LE + P + Fo

(iii) For deserts (where evaporation is almost zero): R = P

(iv) For global oceans as a whole (where redistribution of heat by currents is compensated and is zero): R = LE + P

(b) Energy balance equation of Earth-atmosphere system

This equation can be derived by considering the inflow and expenditure of energy in a vertical column passing downwards from the top of atmosphere to that level in hydrosphere or lithosphere at which noticeable daily or seasonal fluctuations of temperature stop (Figure-1). Energy (heat) flow through the lower base of this column is practically zero.

Energy balance equation of Earth-atmosphere system may given as:

Rs = Fs + L(E - r) + Bs

All the terms on the right-hand side of equation are assumed positive in value when they describe expenditure of energy (heat). The elements of the equations are as discussed below:

(i) Radiation balance of Earth-atmosphere system (Rs): It describes the energy (heat) exchange between the vertical column under consideration and the outer space and is equal to the difference between the amounts of total solar radiation absorbed by the entire column and the total long-wave radiation from column to outer space. It is considered positive when it describes inflow of energy (heat) into the Earth-atmosphere system.

(ii) Total horizontal heat transfer (Fs): It occurs through the sides of the column under consideration and is given as:

Fs = Fo + Fa

where, Fo = horizontal heat transfer through sides of the column in the atmosphere and Fa = horizontal heat transfer through the sides of column in the hydrosphere or lithosphere. Value of Fa is similar to that of Fo and describes the difference of inflow and expenditure of heat in the column of air resulting from atmospheric advection and macroturbulence.

(iii) Heat transfers in change of the state of water: Heat balance of column is also influenced by sources of heat (both positive and negative) that are located within the column itself. These include the inflow and expenditure of heat due to changes in state of water, especially by evaporation and condensation.

Over sufficiently homogeneous surfaces during long periods, the average difference in the magnitudes of condensation and evaporation of water drops in atmosphere is equal to the sum of precipitation (r) and the inflow of heat is equal to Lr. Corresponding component in the energy balance represents the difference between heat inflow from condensation and its expenditure in the evaporation of drops. It may differ from Lr in conditions of rugged surfaces and also in individual short periods of time.

The difference between heat expenditure on evaporation the surface of water bodies, soils and vegetation and heat inflows from condensation on these surfaces are equal to LE.

The overall influence of condensation and evaporation on the column’s energy balance may be approximated in terms L(r -E).

(iv) Changes in the heat content within the column: This change over the period being referred is represented by component Bs in the energy balance equation.

Remaining components of the balance such as heat inflow from dissipation of mechanical energy, difference between heat expenditure and inflow on melting and formation of ice, difference between heat expenditure on photosynthesis inflow from oxidation of biomass etc. are very small and may be neglected.

Consideration of different components of energy balance equation under different conditions shows that:

(i) For an average yearly period, magnitude of Bs is apparently close to zero and the equation simplifies to:

Rs = Fs + L(E - r)

(ii) For the land conditions, the equation becomes:

Rs = Fa + L(E - r)

(iii) For the entire globe, E = r over a period of one year and horizontal inflow of heat into the atmosphere and hydrosphere is apparently zero. Thus the energy balance equation of Earth-atmosphere system for the Earth as a whole simplifies to:

Rs = 0
(c) Energy balance equation of atmosphere

This equation may be obtained by either

(i) Summing up the corresponding flows of heat or

(ii) As difference between members in the heat balance equation for the Earth-atmosphere system and in that for Earth’s surface.

Assuming that atmospheric radiation balance is given by:

Ra = Rs - R

and changes in the heat content of atmosphere (Ba) are given by:

Ba = Bs - B

it can be seen that:

Ra = Fa - Lr - P + Ba

and for an average yearly period, equation is:

Ra = Fa - Lr - P

DISTRIBUTION OF ENERGY BALANCE COMPONENTS
Distribution of energy balance components of Earth’s surface
Important components of energy balance of Earth’s surface which show geographical differences in their values are heat expenditure on evaporation, turbulent heat exchange and redistribution of heat through atmospheric and oceanic currents.

1. Heat expenditure on evaporation: The magnitudes of evaporation from land surface and the oceans in the vicinity of coastlines, differ significantly. This may apparently be explained

(i) differences in the value of possible evaporation on land and on ocean and

(ii) the influence of insufficient moisture in many land areas which limits the intensity evaporation processes and of heat expenditure on evaporation.

At extratropical latitudes, absolute value of heat expenditure on evaporation generally decreases with increasing latitudes. However, major non-zonal changes on land and ocean alter this pattern. In tropical latitudes, distribution of heat expenditure on evaporation is quite complex. Compared to high-pressure regions, its value declines somewhat in the ocean regions adjoining the Equator.

In the oceans, maximum mean latitudinal heat expenditure on evaporation occurs within high-pressure belts. At 50-70 degrees where radiation balances of land and oceans are approximately same, the heat expenditure on evaporation is substantially larger for oceans. This is evidently due to large expenditure of heat brought by ocean currents. In oceans, distribution of warm and cold currents is principal cause of the non-zonal changes in heat expenditure on evaporation. All the major warm currents increase heat expenditure substantially while cold currents reduce it. This may be clearly seen in regions influenced by warm currents like Gulf stream and Kuroshio by old currents like those of Canary Islands, Bengal, California, Peru and Labrador. The yearly evaporation from ocean surface at a particular latitude may change by several time depending on the increase or decrease in water temperature brought about by the currents. In addition, non-zonal in the values of heat expenditure on evaporation and so of evaporation from oceans are also influenced by conditions of atmospheric circulation determining wind velocity and the annual humidity deficit over the oceans. The ocean surfaces have somewhat higher radiation balance than land surfaces and evaporating surfaces may additionally receive a large quantity of heat energy through redistribution of heat by ocean currents. Therefore, evaporation from ocean surface in tropical areas corresponds to a layer of water more than two meters thick.

Table-1. Average values of Earth’s surface energy balance components at various latitudes (kcal/sq. cm/year)

Latit-sude (in degr-ees)
R
LE
P
A
R
LE
P
R
LE
P
A

Ocean
Ocean
Ocean
Ocean
Land
Land
Land
Earth
Earth
Earth
Earth

70-60 N

23

33

16

-26

20

14

6

21

20

9

-8

60-50 N

29

39

16

-26

30

19

11

30

28

13

-11

S
28
31
8
0
49
25
24
72
60
12
0

50-40 N

51

53

14

-16

45

24

21

48

38

17

-7

S
57
55
9
-7
41
21
20
56
53
9
-6

40-30 N

83

86

13

-16

60

23

37

73

59

23

-9

S
82
80
9
-7
62
28
34
80
74
12
-6

30-20 N

113

105

9

-1

69

20

49

96

73

24

-1

S
101
100
7
-6
70
28
42
94
83
15
-4

20-10 N

119

99

6

14

71

29

42

106

81

15

10

S
113
104
5
4
73
41
32
104
90
11
3

10-0 N

115

80

4

31

72

48

24

105

72

9

24

S
115
84
4
27
72
50
22
105
76
8
21

On the land, mean latitudinal value of heat expenditure on evaporation is maximum at equator. These values change within the subtropical high-pressure belts. In both hemispheres, a certain increase in evaporation occurs with increase in latitudes though the increase is more pronounced in Northern Hemisphere. This increase is due to increased precipitation as compared with arid zones at lower latitudes. The distribution of heat expenditure on evaporation from land surface deviates from zonal pattern even more than from oceans. This is due to very great influence of climatic moisture conditions on evaporation. In regions of sufficient soil moisture found at high latitudes and in humid regions at middle and tropical altitudes, heat expenditure on evaporation and the evaporation are governed largely by balance. In regions of insufficient moisture, evaporation is reduced due to insufficient soil moisture while in desert and semi-desert areas, evaporation is almost equal to low yearly total precipitation. Highest heat expenditure on evaporation occurs in certain equatorial regions where in case of abundant moisture and large inflows of heat, it exceeds 60 kcal/sq. cm/year. This corresponds to yearly evaporation of layer of water more than one meter thick.

Further, the patterns of seasonal heat expenditure on evaporation in extratropical latitudes are different on land and oceans. On the land, this expenditure and evaporation decreases substantially during cold season and depending on moisture conditions, attains a maximum at the beginning or in middle of warm season. In contrast, evaporation from oceans usually increases in cold season due to greater difference in temperature of water and air at that time which increases difference in concentration of water vapor on the surface of water and in air. In addition, in many oceanic regions average wind velocities are greater in cold seasons and this also increases evaporation.

2. Turbulent heat exchange: The value of turbulent heat exchange is positive heat is released by Earth’s surface into air and is negative when heat is received by Earth’s surface from atmosphere during the year. Over a year, all the land surfaces except Antarctica and larger part of ocean surfaces release heat into the atmosphere.

In oceans, turbulent heat exchange gradually increases towards higher latitudes. Its magnitude is not large for greater part of ocean surfaces and usually does not exceed 10-20% of the magnitudes of principal components of energy balance equation. Large absolute values of turbulent heat flow, exceeding 30-40 kcal/cm2/year, occur in regions of powerful warm currents e.g. Gulf Stream. Here water is on average warmer than air and at higher latitudes where sea is still free from ice. Cold oceanic currents reduce temperature of water, reduce turbulent heat flow from ocean surface to the atmosphere and increase it in reverse direction.

On land, turbulent heat flow decreases towards higher latitudes. Its maximum value occurs within high-pressure belts which declines somewhat near Equator and sharply decreases at high latitudes. Magnitude of turbulent heat -exchange on continents is greatly influenced by climatic moisture conditions. In arid regions, turbulent heat flow from land surface into the atmosphere is much higher than in humid regions. Highest expenditure of turbulent heat flows on land is found in tropical deserts where it may exceed 60 kcal/sq. cm/year. In humid regions, especially in regions at middle latitudes, heat expenditure through turbulent flows is usually much lower.

The very different patterns of change in turbulent heat exchange on land and in oceans reflect differences in the mechanisms of air mass transformation on the surfaces of continents and oceans.

3. Heat redistribution through water currents: In the heat balance of oceans, inflow or expenditure of energy owing to horizontal exchanges primarily through oceanic currents is very important. A large quantity of heat is redistributed in oceans between tropical and extratropical latitudes. Both warm and cold currents play important role in redistribution of heat in oceans. Regions of increased positive values of that particular component of heat balance (reflecting outflow of heat from ocean surface to lower layers) correspond with regions of cold currents and the regions of reduced negative values correspond with warm currents. Such correspondence is observed for major warm currents e.g. Gulf Stream, Kuroshio and Southwest Pacific Stream as well as for cold currents e.g. Canary Islands, Bengal, California and Peru. Ocean currents carry away heat mainly from a zone ranging from 20 degrees N latitude to 20 degrees S latitude. Maximum of heat absorbed is slightly shifted to the north of Equator. Further, the heat is carried to higher latitudes and expended in the region of 50 degrees to 70 degrees N latitude where warm currents are especially strong.

Studies of Strokina (1963,1969) concerning changes in heat content of ocean’s upper layers over a year have shown that these changes may attain significant magnitudes which are quite comparable with changes in magnitudes of the main components of heat balance. Greatest yearly changes in heat content of ocean’s upper layers (over 25 kcal/sq. cm/year) are observed in Northwestern regions of Pacific ocean and adjoining areas.

Distribution of energy balance components of Earth-atmosphere system

Data for average yearly conditions show that relative proportions of various components of energy balance of Earth-atmosphere change perceptibly at various latitudes.

In equatorial zone, the large inflow of radiation energy is further increased by addition of a substantial inflow of heat produced by changes in state of water through condensation and evaporation. These sources of heat produce large expenditure of heat on atmospheric and oceanic advection. A relatively narrow zone adjoining Equator is and extremely important source of energy for these advection conditions.

At higher latitudes upto 30-40 degrees, a positive radiation balance that decreases with increasing latitude is accompanied by substantial expenditures of energy on water exchange. In most parts of that zone, energy of radiation balance is almost equal to heat expended on water exchange and very little heat is redistributed through air and water currents.

At latitudes above 40 degrees, a zone of negative radiation balance is found. Its absolute value increasing at higher latitudes. The negative radiation balance of that zone is compensated by inflow of heat brought by air and water currents. Proportions of those components within that balance which compensate for the deficiency of radiation energy vary at different latitudes. For the belt between 40--60 degrees, excess energy released in condensation of water is major source of heat while inflow of heat redistributed by ocean currents is also important. At higher latitudes, especially in polar regions, heat inflow from condensation is very small and influence of ocean currents is either absent (in South polar zone) or is weak due to permanent ice cover (in North polar zone). At these latitudes, redistribution of heat through atmospheric circulation is major source of heat.

The average values of various components of energy balance of Earth-atmosphere system over six-month periods at various latitudes have been studied (Table-2). These show that magnitude of radiation absorbed by Earth-atmosphere system (Qa) is not the only factor determining the magnitude of outgoing long-wave radiation at the top of atmosphere (Is). For middle and high latitudes during October to March in Northern Hemisphere and for high latitudes in Southern Hemisphere throughout the entire year, the main source of heat is heat-transfer from lower latitudes through atmospheric circulation.

Distribution of energy balance components of atmosphere
The average radiation balance of atmosphere at various latitudes changes less than other components of heat balance. The large absolute negative values for the atmospheric radiation-balance observed at all latitudes are compensated largely by inflows of heat from condensation. The role of heat from Earth’s surface through turbulent heat exchange is less important though the influence is quite perceptible.

Distribution of components of energy balance of whole Earth
Depending on the relative proportions of land and ocean areas in particular zones, mean latitudinal distribution of the components of energy balance of Earth as a whole is characterized by patterns typical of continents or by the patterns typical of oceans. Average values of energy balance components for individual continents and oceans (Table-3) show that in three continents (Europe, North America and South America) greater share of energy radiation balance is expended on evaporation. In the remaining three continents (Asia, Africa and Australia) where dry climates prevail, opposite is true.

Energy balance components of three oceans show little difference from each other. For each ocean the sum of heat expenditure on evaporation and turbulent heat exchange is close to the magnitude of radiation balance. This means that the heat exchange among different oceans resulting from currents does not exert any substantial influence on the heat balances of individual oceans.

The values of the components of energy balance for Earth a whole show that in oceans approximately 90% of the energy of radiation balance is expended on evaporation and only 10% on direct turbulent heating of atmosphere. These magnitudes are nearly same on land. For Earth as a whole, 83% of the energy of radiation balance is expended on evaporation 17% on turbulent heat exchange.

The values of the components of energy balance for the Earth as a whole are shown in Figure-2. Overall yearly flux of solar radiation entering outer boundary of troposphere is approximately 1000 kcal/sq. cm. Due to the spherical shape of Earth, about 25% of this yearly flux (i.e. 250 kcal/sq.cm), passes through a unit surface of the upper boundary of troposphere. Assuming that Earth’s albedo (As) is 0.33, short-wave radiation absorbed by Earth represented by Qs(1-As) is approximately 167 kcal/sq. cm/year. Out of this, short-wave radiation reaching Earth’s surface is 126 kcal/sq. cm/year. Average value of albedo at Earth’s surface (A) is 0.14. This takes into account the differences in value of incoming solar radiation in various regions. Thus the amount of short-wave radiation absorbed at Earth’s surface, represented by Q(1-A), is 108 kcal/sq. cm/year and 18 kcal/sq. cm/year is reflected back from the surface. The atmosphere absorbs about 59 kcal/sq. cm/year which is substantially less than that absorbed at Earth’s surface. Since radiation balance of Earth’s surface (R) is 72 kcal/sq. cm/year, average effective radiation of Earth’s surface (I) comes to be 360 kcal/sq. cm/year. Overall value of Earth’s long-wave radiation (Is) is quite close to 167 kcal/sq. cm/year. The ratio I/Is much less than

Table 2. Mean latitudinal values of energy balance components of Earth-atmosphere system for six-month periods (kcal/sq. cm/year) April-September

Latitude (in degrees)
Qa
Fa
Fo
Bs
Is

80-90 N
7.8
-4.5
0.0
0.8
11.5

S
0.0
-8.8
0.0
0.0
8.8

70-80 N
8.2
-4.4
0.0
0.8
11.8

S
0.2
-9.8
0.0
0.0
10.0

60-70 N
11.5
-1.8
-0.4
1.2
12.5

S
1.0
-9.5
0.0
0.8
11.3

50-60 N
14.6
0.0
-1.3
2.8
13.1

S
3.3
-3.9
-2.6
-2.5
12.3

40-50 N
16.9
1.0
-2.0
3.9
14.0

S
5.9
-1.9
-1.6
-3.5
12.9

30-40 N
19.2
1.4
-1.7
4.3
15.2

S
8.9
-0.4
-0.4
-4.2
13.9

20-30 N
20.0
2.0
-0.4
2.9
15.5

S
13.0
1.4
0.3
-3.4
14.7

10-20 N
19.7
2.4
0.9
1.4
15.0

S
16.2
2.6
0.9
-2.5
15.2

0-10 N
18.4
1.4
2.2
-0.1
14.9

S
18.0
2.3
2.2
-1.5
15.0

October- March

80-90 N
0.1
-9.1
0.0
-0.8
10.0

S
3.4
-6.9
0.0
0.0
10.3

70-80 N
0.5
-9.3
0.0
-0.8
10.6

S
4.4
-6.5
0.0
0.0
10.9

60-70 N
1.8
-6.7
-1.5
-1.2
11.2

S
8.1
-4.3
0.0
0.8
11.6

50-60 N
4.0
-4.7
-0.5
-2.8
12.0

S
12.8
-2.6
0.6
2.5
12.3

40-50 N
6.5
-2.9
0.6
-3.9
12.7

S
15.9
0.0
-0.6
3.5
13.0

30-40 N
9.5
-0.9
0.7
-4.3
14.0

S
18.9
2.0
-1.4
4.2
14.1

20-30 N
13.7
0.9
0.6
-2.9
15.1

S
20.6
3.5
-0.3
2.5
15.0

10-20 N
17.0
1.8
1.0
-1.4
15.6

S
20.7
3.5
-0.3
2.5
15.0

0-10 N
18.7
2.1
1.4
0.1
15.1

S
19.7
2.4
0.8
1.5
15.0

Table-3. Energy balance of continents and oceans (kcal/sq. cm/year)

Continent
R
LE
P
Ocean
R
LE
P

Europe
39
24
15
Atlantic
82
72
8

Asia
47
22
25
Pacific
86
78
8

Africa
68
26
42
Indian
85
77
7

N.America
40
23
17
S.America
70
45
25

Australia
70
22
48

the ratio Q(1-A)/Qs(1-As). This difference shows that greenhouse effect has very large influence on the thermal processes of Earth. Due to this effect, Earth receives about 72 kcal/sq.cm/year of radiation energy. This energy is partly expended on evaporation of water (LE = 60 kcal/sq. cm/year) and partly returned to the atmosphere by turbulent heat losses (P = 12 kcal/sq. cm/year). Thus, the energy balance of atmosphere has following components:

(i) Heat inflow from absorbed short-wave radiation = 59 kcal/sq. cm/year

(ii) Heat inflow from condensation of water vapor (Lr) = 60 kcal/sq. cm/year

(iii) Heat inflow from turbulent heat losses at the Earth’s surface = 12 kcal/sq. cm/year

(iv) Heat expenditure on effective radiation into outer space (Is - I) = 131 kcal/sq. cm/year.

The last figure corresponds to the sum of first three components of energy balance.

SOLAR RADIATION AND PLANETARY TEMPERATURE

The temperature of a planet irradiated by solar radiation can be estimated by balancing the amount of radiation absorbed (Ra) against the amount of outgoing radiation (Ro). The Ra will be the product of:

(i) Solar irradiance (I)

(ii) Area of planet. Area of planet relevant for such calculations is the area of the planet as seen by incoming radiation which is given by r2 where r = radius of the planet.

(iii) Absorbed fraction of radiation. The fraction of radiation that is absorbed is given by (1 - A where A = albedo of planet. This albedo represents the fraction of radiation that is reflected back from the planet.

Figure. 2. Energy balance of the Earth. (Components values in kcal/cm2/year).

Thus the energy absorbed by the planet will be:

Ra = I  (1 - A)

Intensity of outgoing radiation of a body is given by Stefan-Boltzmann Law i.e.
Io =  T4
where = Stefan-Boltzmann Constant = 5.6 x 10-8 Wm-2 K-4. The total energy radiated by the planet will be the product of the intensity of outgoing radiation (Io) and the area of the whole planetary surface giving out radiation (4  r 2). Thus, the outgoing radiation (Ro) from the planet is given by:

Ro = 4r2 T4

Effective planetary temperature

Since Ra = Ro i.e. system is assumed to be in steady-state where radiation absorbed and outgoing radiation are equal, an expression for the effective planetary temperature (Te) can be obtained from the above equation and it may be given by:

Te = [I - (1 - A)/4 ]0.25
In this expression of effective planetary temperature, effect of atmosphere has not been taken into account. For Earth, solar irradiance (I) at the top of atmosphere is about 1.4 x 103/m2/s and albedo of Earth as a whole is about 0.33. From these values, the calculated equilibrium temperature of Earth comes to be 254 K. However, the actual observed average ground level temperature of Earth is about 288 K. This higher effective temperature of Earth from the calculated value is due to the greenhouse-effect of atmosphere.

The black-body spectrum of Earth at 288 K shows that radiation from Earth is of much longer wavelength and is at much lower intensity than radiation from Sun. The absorption spectrum of Earth’s atmosphere overlaps fairly well with the solar emission spectrum. Except for a very narrow window in the absorption bands, much of the long-wave radiations from Earth correspond with the region of absorption in the atmosphere. This means that much of the incoming radiation reaches the Earth’s surface while the outgoing thermal radiation is largely absorbed by the atmosphere rather than being lost to space. Thus, the effect of atmosphere is to trap the outgoing thermal radiation. This effect is termed green-house effect.. The thermal radiation i.e. the heat trapped by the atmosphere due to green-house effect is responsible for the effective temperature of Earth being higher than the temperature calculated without taking into account the effect of atmosphere. In general, absorption of re-emitted long-wave radiation and vertical mixing processes determine the temperature profile of the lower part of atmosphere (troposphere) which in turn determine the Earth’s temperature.

Optical depth of atmosphere and Earth’s surface temperature
The atmosphere is not transparent to the outgoing long-wave radiation and much of this radiation is absorbed in the lower part of the atmosphere, which is warmer than the upper parts. Simple radiative equilibrium models have been developed for Earth and to account for this effect, these models divide the atmosphere into layers that are just thick enough to absorb the outgoing radiation. These atmospheric layers are said to be optically thick and the atmosphere is discussed in terms of its optical depth based on the number of these atmospheric layers of different optical thickness. Earth’s atmosphere is sometimes said to have two layers while that of planet Venus has almost 70 layers which are largely due to enormous amount of CO2 in the atmosphere of Venus. The radiation equilibrium model indicates that the effective planetary temperature (Te) is thus related to ground-level planetary temperature (Tg) by the equation:

Tg4 = (1 - )Te4 (where  = optical depth of atmosphere)

The optical depth of atmosphere increases with increase in atmospheric concentrations of carbon dioxide and water vapor because both these are principal atmospheric absorbers of outgoing long-wave radiation. With increasing concentrations of CO2 in lower layers of atmosphere, other such gases that are responsible for radiating heat to outer space are pushed to slightly higher and colder levels of atmosphere. The radiating gases will radiate heat less efficiently because they are colder at higher altitudes. Thus, the atmosphere becomes less efficient radiator of heat and this results in rise of atmospheric temperature. This rise in atmospheric temperature, in turn, leads to more evaporation and increase in atmospheric water vapor, which is a greenhouse gas and further increases the absorption of outgoing long-wave thermal radiation. This positive feedback results in further increase in atmospheric temperature. The model also suggests that increase in atmospheric CO2 is associated with decrease in temperatures of upper (stratospheric).

Vertical heat transport and Earth’s surface temperature
Simple models of radiation balance of atmosphere do not take into account various other processes that transport heat vertically in the atmosphere and, therefore, overestimate the surface temperature of Earth. Convection is major process of vertical heat transport and is very important in lowering the surface temperature. Convection occurs because warm air is lighter than cool air and so rises upwards carrying heat from Earth’s surface to the upper atmosphere. As warm air rises up, it expands due to fall in pressure and work done in expansion causes it to cool adiabatically. Thus,

Cv T = - P V (where Cv = molar heat capacity at constant volume)

Ideal gas equation PV = RT takes the differential form P dV + V dP = R dt which may be rearranged in incremental form as:

- P V + R  = V P
This equation may be combined with equation Cv T = - P V using the fact that Cp - Cv = R, where Cp = molar heat capacity at constant pressure = 29.05 J/mol/K. This results in following equation:

Cp T = (Cv + R) T = - P V + R T = V P = (RT/P) P .............(a)

It can be shown that P/P = - Mmg z /RT where Mm = mean molecular weight of air = 0.028966 kg/mol; g = acceleration due to gravity = 9.8065 m/s/s; z = altitude. This gives:

RT/P = - Mmg z/ P.......................................................(b)

Substitution of the above equation (b) in equation (a) gives:

Cp T = - Mmgz

or, T/ z = - (Mmg/Cp)

For Earth’s atmosphere, the lapse rate ( T/ z) works out to be -9.8 k/km for dry air. However, the air is usually wet and as it rises up, it releases latent heat so the measured lapse rate is -6.5 K/km.

If atmospheric temperature falls much less slowly with height than the lapse rate (or even rises with height) then inversion conditions exist and air is very stable with respect to vertical convective mixing. Conversely, if temperature falls very rapidly with height, at a rate greater than lapse rate, then the atmosphere is unstable and convective mixing will be active.

Short-wave radiation and temperature

The discussion till now has assumed total transparency of atmosphere to incoming solar radiation. Though it is true for visible range of radiation, it is not true for ultra-violet region of the solar spectrum. Though the amount of such short-wave radiation is very small, it has important consequences for the temperature of Earth-atmosphere system.

Various ultra-violet wavelengths are absorbed in the atmosphere at different heights. At just over 40 km, absorption of ultra-violet radiation by ozone results in considerable warming of stratosphere and in this zone, temperature rises with altitude. Average temperature of stratosphere is 250 K. Considering it to be a black-body radiator, maximum power radiation would be expected at 11.5 m. This value is very close to absorption band of carbon dioxide which means that this gas also plays important role in stratospheric temperature. Increase in concentration of carbon dioxide in stratosphere might allow more effective radiation from stratosphere and, therefore, its cooling. This effect is quite opposite to that noted for troposphere.

Further, at the altitude of thermosphere, atmosphere is very thin. In this zone, molecules are exposed to unattenuated solar radiation of extremely short wavelength i.e. of high energy. This radiation arises from the outer region of Sun. At wavelengths below 50 nm, effective emission temperature exceeds 10,000 K. High-energy solar protons of such wavelengths are absorbed by gas molecules giving them high transitional energies i.e. high temperatures. The energies may be large enough to dissociate oxygen and nitrogen. Temperatures in thermosphere undergo wide variations depending upon the state of Sun. During solar disturbances, output of high-energy protons is very much enhanced that results in very high atmospheric temperatures. Temperature in this zone may further be increased by another mechanism. The temperature is normally defined in terms of transitional energy but absorption and emission of radiation occur through vibrational and rotational changes. In upper atmosphere, the frequency of molecular collisions is relatively low and so exchange of translational, vibrational and rotational energies is infrequent. Hence the cooling of thermosphere by re-radiation is very inefficient. The temperature of thermosphere increases with height so it is also stable against convection. Heat can be lost only by very inefficient diffusion processes and as a result, thermospheric temperatures are extremely high.

The concept of energy return on energy invested, or EROEI, is terribly misunderstood. I have heard people argue that EROEI doesn't matter, only economics. This misses a very key point: EROEI is going to have a huge impact on economics, because it shows that in order to maintain current net energy for society, energy production must accelerate as EROEI declines.

Likewise, I have heard people hand wave away the issue, suggesting it is really no big deal. Here's an example that I saw yesterday in a thread at The Oil Drum:

Consider an EROEI of 20 with 10 units required; this means that 1 unit is invested to get 20 unit of output or if 10 units are required then .5 unit is invested. Add them together an you get a total of 10.5 units.

Try it with an EROEI of 10; 10+1=11 units
Try it with an EROEI of 3; 10+10/3=13.33 units
Try it with an EROEI of 1.5; 10+20/3=16.66 total units of energy.

(At a EROEI of 1.11; 10+9=19. But I don't know an energy process that runs that low)

So going from an EROEI of 20 to 1.5 raises the total amount of base energy extracted to maintain an output of 10 units would have to increase by only 59%--(16.66/10.5)-1.

The amount of low EROEI unconventional oil (for example) in the world is probably 2 times greater than conventional oil in the ground. There is still enough total energy to makeup for the drop in EROEI and still maintain the current levels of production given sufficent effort.

The object of energy production is to produce energy, not worry about EROEI.

That last sentence sums up the person's argument: EROEI is no big deal. Being a math type, I worked through his calculations and found that they are wrong. It took me a while to see his error, but I finally did see it. Work the problem in reverse at an EROEI of 1.5. If you produced 16.66 units of energy at an EROEI of 1.5, then the inputs were 16.66/1.5, or 11.1. The actual net is 16.66 - 11.1, or 5.56. He was trying to net 10 units, so he has vastly underestimated the energy inputs required for this. So of course he doesn't think EROEI is a problem. He doesn't understand the concept.

EROEI Basics

There are a couple of important EROEI equations. The first is that EROEI = Energy Output/Energy Input. In other words, if we have to spend 10 BTUs (Input) to extract and refine 100 BTUs of oil (Output), then the EROEI is 100 to 10, or 10 to 1. The second important equation concerns the net energy; that is how much energy was left after the energy input is accounted for. This equation is Net Energy = Energy Output - Energy Input. In our previous example, the net energy is (100 BTUs produced - 10 BTUs input), or 90 BTUs.

A couple of points here. First, the break even for EROEI is 1.0. In that case, you have input just as much energy into the process as you got back out. In some cases, that may make economic sense. For instance, if you input coal BTUs but got back out ethanol or diesel BTUs, then you have converted the coal into something of greater value. However, if you input one transportation fuel and got another transportation fuel as output - as is mostly the case with corn ethanol (natural gas, diesel, and gasoline in; ethanol out) - then you are really just spinning your wheels. In a case like this, you should just use the inputs directly as a transportation fuel.

The same is true of Net Energy - it can be negative and yet still make economic sense. But an important point here is that society can't run for long on an EROEI of less than 1.0 or on a negative Net Energy. Doing so is equivalent to withdrawing money from a bank - at some point you have to make some deposits - or at least stop the withdrawals.

The EROEI of Brazilian Ethanol

The case of Brazilian sugarcane ethanol deserves special mention. It is often quoted as having an EROEI of 8 to 1. I have even repeated that myself. But this is misleading. This measurement is really a cousin of EROEI. What is done to get the 8 to 1 sugarcane EROEI is that they only count the fossil fuel inputs as energy. Boilers are powered by burning bagasse, but this energy input is not counted. For a true EROEI calculation, all energy inputs should be counted. So what we may see is that the EROEI for sugarcane is 2 to 1 (hypothetically) but since most inputs are not fossil-fuel based the EROEI based only on fossil-fuel inputs is 8 to 1.

What is overlooked by touting the EROEI of 8 to 1 and skipping over the true EROEI is an evaluation of whether those other energy inputs could be better utilized. For instance, that bagasse that doesn't get counted could be used to make electricity instead. Probably in the case of sugarcane, firing boilers is the best utilization. But the lesson from this digression is to be careful when people are touting very high EROEIs. They probably aren't really talking about EROEI.

Calculations

Now for some calculations that show the challenge of energy production if the EROEI of our energy sources continues to decline. In the early days of oil production, the EROEI was over 100. Now, it has declined to somewhere between 10 and 20. So let's look at the implications as the EROEI declines from 20. Here is what it takes to get 10 units of energy (gross, not net) at various EROEI values.

A 20 to 1 EROEI it takes an investment of 0.5 energy units to get 10 out

At 10 to 1 it takes 1 energy unit to get 10 out

At 5 to 1 it takes 2 energy units to get 10 out

At 2 to 1 it takes 5 energy units to get 10 out

At 1.5 to 1 it takes 6.67 energy units to get 10 out

At 1.3 to 1 it takes 7.69 energy units to get 10 out

At 1 to 1 it takes 10 energy units to get 10 out

So, dropping from an EROEI of 20 to 1 down to 1.3 to 1 takes over 15 times the energy inputs (7.69/0.5) to output the same amount of energy.

Net Energy

But here is what so many - included that poster I quoted above - fail to understand. Look at the net energy.

At 20 to 1, an investment of 0.5 units got 10 back out. The net is 9.5 units.

At 1.3 to 1, it took an investment of 7.69 units got 10 back out. The net is 2.31 units.

At 1 to 1, an investment of 10 units got 10 back out. The net is 0 units - all you have done is converted one energy form into another. (And of course at less than 1 to 1, you have actually lost usable energy during the process).

If we wish to net 10 units, then at 20 to 1 we have to produce a total of 10.53 units (you are solving 2 equations here; EROEI = Out/In and Net = Out - In; For EROEI = 20, the solution is Out = 10.53 and In = 0.53). For an economy that requires 10 units of energy to run, we need an excess of 0.53 units to net that 10. (And if you want to pick nits, 10.53 is rounded from 10.5263157894737).

Now drop the EROEI to 1.3. We now have to produce a total of 43.33 – an excess of 33.33 - to get the 10 we need to run the economy (Out = 43.33, In = 33.33; EROEI = 1.3 = 43.33/33.33; Net = 10 = 43.33 - 33.33). Thus, the requirement from dropping the EROEI from 20 to 1 down to 1.3 to 1 requires a production excess of (33.33/0.53), or over 60 times the high EROEI case.

Running Faster to Stay in Place

Therein EROEI illustrates clearly the challenge we face. As EROEI declines, energy production must accelerate just to maintain the same net energy for society. At an EROEI of less than 2, the amount of energy required to net our current energy usage far exceeds even the most optimistic proposals for our production capacity. Others have concluded much the same: The status quo can't be maintained if EROEI continues to decline.

Many don’t grasp this concept. If they did, they would understand why a falling EROEI is reason for concern.

______________________________

Letter to Science

Michael Wang

Center for Transportation Research

Argonne National Laboratory

Zia Haq

Office of Biomass Program

Office of Energy Efficiency and Renewable Energy U.S. Department of Energy

The article by Searchinger et al. in Sciencexpress ("Use of U.S.

Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change," February 7, 2008) provides a timely discussion of fuel ethanol's effects on greenhouse gas (GHG) emissions when taking into account GHG emissions from potential land use changes induced by ethanol production.

Land use change issues associated with biofuels were explored in life-cycle analyses beginning in early 1990s (Delucchi 1991). In general, the land use changes that occur as a result of biofuel production can be separated into two categories: direct and indirect.

Direct land use changes involve direct displacement of land for farming of the feedstocks needed for biofuel production. Indirect land use changes are those made to accommodate farming of food commodities in other places in order to maintain the global food supply and demand balance.

Searchinger et al. used the GREET model developed by one of us at Argonne National Laboratory in their study (see Wang 1999). They correctly stated that the GREET model includes GHG emissions from direct land use changes associated with corn ethanol production; the emissions estimates in GREET are based on land use changes modeled by the U.S. Department of Agriculture (USDA) in 1999 for an annual production of 4 billion gallons of corn ethanol in the United States by 2010. Needless to say, the ethanol production level simulated by USDA in 1999 has been far exceeded by actual ethanol production - about 6 billion gallons in

2007 (Renewable Fuels Association 2008). Thus, the resultant GHG emissions from land use changes provided in the current GREET version need to be updated. Argonne, and several other organizations, recently began to address both direct and indirect land use changes associated with future, much-expanded U.S. biofuel production. Such an effort requires expansion and use of general equilibrium models at the global scale.

Many critical factors determine GHG emission outcomes of land use changes. First, we need to clearly define a baseline for global food supply and demand and cropland availability without the U.S. biofuel program. It is not clear to us what baseline Searchinger et al. defined in their modeling study.

Searchinger et al. modeled a case in which U.S. corn ethanol production increased from 15 billion gallons a year to 30 billion gallons a year by 2015. However, in the 2007 Energy Independence and Security Act (EISA), Congress established an annual corn ethanol production cap of 15 billion gallons by 2015. Congress established the cap - based on its awareness of the resource limitations for corn ethanol production - to help prevent dramatic land use changes. Thus, Searchinger et al. examined a corn ethanol production case that is not directly relevant to U.S. corn ethanol production in the next seven years.

Corn yield per acre is a key factor in determining the total amount of land needed for a given level of corn ethanol production. It is worth noting that U.S. corn yield per acre has steadily increased - nearly 800% in the past 100 years (Perlack et al. 2005). Between 1980 (the beginning of the U.S. corn ethanol program) and 2006, per-acre corn yield in the United States has increased at an annual rate of 1.6% (Wang et al. 2007). Seed companies are developing better corn seeds that resist drought and pests and use nitrogen more efficiently. Corn yield could increase at an annual rate of 2% between now and 2020 and beyond (Korves 2007). Despite these trends, Searchinger et al. used a constant corn yield, assuming that low yields from corn fields converted from marginal land would offset increased yields in existing corn fields. A more accurate approach would be to use the increased yields in existing corn fields, determine how much additional land was required for corn farming in the United States, and then use the corresponding yield of the new corn fields (some of which could be converted from marginal land). Searchinger et al. further assumed constant corn yield in other countries, many of which have lower corn yields and, consequently, greater potential for increased yields.

Searchinger et al. also assumed that distillers' grains and solubles

(DGS) from corn ethanol plants would displace corn on a pound-for-pound basis. The one-to-one displacement ratio between DGS and corn fails to recognize that the protein content of DGS is much higher than that of corn (28% vs. 9%). The actual displacement value of DGS is estimated to be at least 23% higher than that assumed by Searchinger et al.

(Klopfenstein et al. 2008).

Searchinger et al. estimated that U.S. corn ethanol production (between

15 billion and 30 billion gallons) would result in an additional 10.8 million hectares of crop land worldwide: 2.8 million hectares in Brazil, 2.3 million hectares in China and India, and 2.2 million hectares in the United States, and the remaining hectares in other countries. The researchers maintain that the United States has already experienced a 62% reduction in corn exports. Actually, U.S. corn exports have fluctuated around the 2-billion-bushel-a-year level since 1980. In 2007, when U.S. corn ethanol production increased dramatically, its corn exports increased to 2.45 billion bushels - a 14% increase from the 2006 level. This increase was accompanied by a significant increase in DGS exports by the United States - from 0.6 million metric tons in 1997 to 3 million metric tons in 2007.

Searchinger et al. had to decide what land use changes would be needed in Brazil, the United States, China, and India to meet their simulated requirement for 10.8 million hectares of new crop land. With no data or modeling, Searchinger et al. used the historical land use changes that occurred in the 1990s in individual countries to predict future land use changes in those countries (2015 and beyond). This assumption is seriously flawed by predicting deforestation in the Amazon and conversion of grassland into crop land in China, India, and the United States. The fact is, deforestation rates have already declined through legislation in Brazil and elsewhere. In China, contrary to the Searchinger et al. assumptions, efforts have been made in the past ten years to convert marginal crop land into grassland and forest land in order to prevent soil erosion and other environmental problems.

In estimating the GHG emissions payback period for corn ethanol, Searchinger et al. relied on the 20% reduction in GHG emissions that is provided in the GREET model for the current ethanol industry. Future corn ethanol plants could improve their energy efficiency by avoiding DGS drying (in some ethanol plants) or switching to energy sources other than natural gas or coal, either of which would result in greater GHG emissions reductions for corn ethanol (Wang et al. 2007). Searchinger et al. failed to address this potential for increased efficiency in ethanol production.

In one of the sensitivity cases, Searchinger et al. examined cellulosic ethanol production from switchgrass grown on land converted from corn farms. Cellulosic biomass feedstocks for ethanol production could come from a variety of sources. Oak Ridge National Laboratory completed an extensive assessment of biomass feedstock availability for biofuel production (Perlack et al. 2005). With no conversion of crop land in the United States, the study concludes that more than 1 billion tons of biomass resources are available each year from forest growth and by-products, crop residues, and perennial energy crops on marginal land.

In fact, in the same issue of Sciencexpress as the Searchinger et al.

study is published, Fargione et al. (2008) show beneficial GHG results for cellulosic ethanol.

On the basis of our own analyses, production of corn-based ethanol in the United States so far results in moderate GHG emissions reductions.

There has also been no indication that U.S. corn ethanol production has so far caused indirect land use changes in other countries because U.S. corn exports have been maintained at about 2 billion bushels a year and because U.S. DGS exports have steadily increased in the past ten years.

U.S. corn ethanol production is expected to expand rapidly over the next few years - to 15 billion gallons a year by 2015. It remains to be seen whether and how much direct and indirect land use changes will occur as a result of U.S. corn ethanol production.

The Searchinger et al. study demonstrated that indirect land use changes are much more difficult to model than direct land use changes. To do so adequately, researchers must use general equilibrium models that take into account the supply and demand of agricultural commodities, land use patterns, and land availability (all at the global scale), among many other factors. Efforts have only recently begun to address both direct and indirect land use changes (see Birur et al. 2007). At this time, it is not clear what land use changes could occur globally as a result of U.S. corn ethanol production. While scientific assessment of land use change issues is urgently needed in order to design policies that prevent unintended consequences from biofuel production, conclusions regarding the GHG emissions effects of biofuels based on speculative, limited land use change modeling may misguide biofuel policy development.

References

Birur, D.K., T.W. Hertel, and W.E. Tyner, 2007, The Biofuel Boom: The Implications for the World Food Markets, presented at the Food Economy Conference, the Hague, the Netherlands, Oct. 18-19.

Delucchi, M.A., 1991, Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity, ANL/ESD/TM-22, Volume 1, Center for Transportation Research, Argonne National Laboratory, Argonne, Ill., Nov.

Fargione, J., J. Hill, D. Tilman, S. Polasky, and P. Hawthorne, 2008, "Land Cleaning and Biofuel Carbon Debt," Sciencexpress, available at www.sciencexpress.org, Feb. 7.

Klopfenstein, T. J., G.E. Erickson, and V.R. Bremer, 2008, "Use of Distillers' By-Products in the Beef Cattle Feeding Industry,"

forthcoming in Journal of Animal Science.

Korves, R., 2007, The Potential Role of Corn Ethanol in Meeting the Energy Needs of the United States in 2016-2030, prepared for the Illinois Corn Marketing Board, Pro-Exporter Network, Dec.

Perlack, R.D., L.L. Wright, A. Turhollow, R.L. Graham, B. Stokes, and D.C. Urbach, 2005, Biomass as Feedstock for Bioenergy and Bioproducts

Industry: the Technical Feasibility of a Billion-Ton Annual Supply, prepared for the U.S. Department of Energy and the U.S. Department of Agriculture, ORNL/TM-2005/66, Oak Ridge National Laboratory, Oak Ridge, Tenn., April.

RFA (Renewable Fuels Association), 2008, Industry Statistics, available at http://www. ethanolrfa.org/industry/statistics/, accessed Feb. 13, 2008.

Searchinger, T., R. Heimlich, R.A. Houghton, F. Dong, A. Elobeid, J.

Fabiosa, S. Tokgoz, D. Hayes, and T.H. Yu, 2008, "Use of U.S. Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change," Sciencexpress, available at www.sciencexpress.org, Feb. 7.

Wang, M., 1999, GREET 1.5 - Transportation Fuel-Cycle Model, Volume 1:

Methodology, Development, Use, and Results, ANL/ESD-39, Volume 1, Center for Transportation Research, Argonne National Laboratory, Argonne, Ill., Aug.

Wang, M, M. Wu, and H. Hong, 2007, "Life-Cycle Energy and Greenhouse Gas Emission Impacts of Different Corn Ethanol Plant Types," Environmental Research Letter, 2: 024001 (13 pages).

He is employed by the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC), in Greenbelt, Maryland and is also the director of the Goddard Institute for Space Studies (GISS), in New York City. He is also a senior scientist in the Columbia University Earth Institute and an Adjunct Professor of Earth and Environmental Sciences at Columbia. He is responsible for defining the research direction of the Goddard Institute, obtaining research support for the Institute, carrying out original scientific research directed principally toward understanding global change, and providing relevant information to the public. He rpobably knows what he is talking about. 

Dr Hansen gave testimony to a number of US congressional committees twenty or so years ago. As a result of this the concept of global warming became widely known; many people disagreed with his science at first, but now almost all scientists agree with Hansen’s ideas. 

James Hansen was not the first person to come up with a theory that climate change is being caused by humans beings; in 1895 a Swedish scientist, Svante Arrenius, drawing on observations by Tyndall thirty years earlier who drew on Fourier in 1827 who concluded that the atmosphere operates like glass in a greenhouse and that increased amounts of carbon dioxide, especially from coal burning, was causing a greenhouse effect. 

Hansen thinks that global warming has been in part mitigated by a cooling effect of aerosols; otherwise it would have been far worse.

Dr Hansen is now worried by developed countries thinking of building new coal powered power stations. He warns against Germany and the United Kingdom building more coal fired power stations until they have developed the technology for sequestrating the carbon. Dr Hansen argues that burning fossil fuels, (coal, oil and gas), increases the amount of carbon dioxide (CO2) and other gases and particles in the air. These gases and particles affect the Earth’s energy balance, changing both the amount of sunlight absorbed by the planet and the emission of heat (long wave or thermal radiation) to space. The net effect is a global warming that has become substantial during the past three decades.  

He believes that global warming from continued burning of more and more fossil fuels poses clear dangers for the planet and for the planet’s present and future inhabitants because coal is the largest contributor to the human-made increase of CO2 in the air. He feels that rather than building new coal fired power stations we should phase out the use of coal entirely, unless its CO2 is captured and sequestered. Coal has more imbedded carbon in it than any other fossil fuel.

If James Hansen is right then the rising demand for power in the United Kingdom will cause us some problems. The availability of natural gas to Western Europe will likely fall as it becomes too scarce or expensive; oil will inevitably become more expensive (nearly $100 and rising) and as Western Europe has very little natural gas and oil it will to dig up or import coal and burn it to generate electricity.

Already Germany and the United Kingdom are thinking about two projects for new coal fired power stations. These kinds of projects or usually offered with assurances about carbon sequestration and public safety, but these promises are usually worthless as the reality of commercial interests kicks in and the multinational businesses to profit while the rest of the world pays the bill. 

Dr Hansen is probably worried about the number of coal fired power stations being built in China – around two every week at the last count. China’s carbon dioxide emissions are as a consequence rising at above 10% per annum, compared with rises of around 1½ % for the USA and the United Kingdom. China is now the developed countries’ industrial heartland; most of our goods are made there. It has replaced the Ruhr in Germany, the Midlands of England and the industrial cities of the mid west of America.  

Venture capitalists always encourage people to have goods and products made in China because labour prices are cheap there, and as a result the world is getting cheap but very dirty industry. Many will profit as economies grow and people become wealthier and able to consume more, buying goods far cheaper than otherwise and the environment suffers. We may not get the fog and smog from China in London, but the carbon dioxide and other greenhouse gases are evenly distributed around the world.

No venture capitalist is really interested in the environment when care of it stands in the way of a profit. Dragons in the den breathe fire, emitting carbon dioxide copiously. 

Dr Hansen has gone on record that if we continue our present rate of emissions then by 2016 the changes in our climate will be irreversible. I hope that he is wrong, because I see no sign of there being the will or the desire to undertake the fundamental changes that are necessary. 

It is a great feeling to help and gives me great satisfaction, so if I can be of help let me know and don't deprive me of this satisfaction.

Oro Selket

The Salk Institute scientist who earlier discovered that enhancing the function of a single protein produced a mouse with an innate resistance to weight gain and the ability to run a mile without stopping has found new evidence that this protein and a related protein play central roles in the body's complex journey to obesity and offer a new and specific metabolic approach to the treatment of obesity related disease such as Syndrome X (insulin resistance, hyperlipidemia and atherosclerosis).

Dr. Ronald M. Evans, a Howard Hughes Medical Investigator at The Salk Institute's Gene Expression Laboratory, presented two new studies (date) at Experimental Biology 2005 in the scientific sessions of the American Society for Biochemistry and Molecular Biology. The studies focus on genes for two of the nuclear hormone receptors that control broad aspects of body physiology, including serving as molecular sensors for numerous fat soluble hormones, Vitamins A and D, and dietary lipids.

The first study focuses on the gene for PPARd, a master regulator that controls the ability of cells to burn fat. When the "delta switch" is turned on in adipose tissue, local metabolism is activated resulting in increased calorie burning. Increasing PPARd activity in muscle produces the "marathon mouse," characterized by super-ability for long distance running. Marathon mice contain altered muscle composition, which doubles its physical endurance, enabling it to run an hour longer than a normal mouse. Marathon mice contain increased levels of slow twitch (type I) muscle fiber, which confers innate resistance to weight gain, even in the absence of exercise.

Additional work to be reported at Experimental Biology looks at another characteristic of PPARd: its role as a major regulator of inflammation. Coronary artery lesions or atherosclerosis are thought to be sites of inflammation. Dr. Evans found that activation of PPARd suppresses the inflammatory response in the artery, dramatically slowing down lesion progression. Combining the results of this new study with the original "marathon mouse" findings suggests that PPARd drugs could be effective in controlling atherosclerosis by limiting inflammation and at the same time promoting improved physical performance.

Dr. Evans says he is very excited about the therapeutic possibilities related to activation of the PPARd gene. He believes athletes, especially marathon runners, naturally change their muscle fibers in the same way as seen in the genetically engineered mice, increasing levels of fat-burning muscle fibers and thus building a type of metabolic 'shield" that keeps them from gaining weight even when they are not exercising.

But athletes do it through long periods of intensive training, an approach unavailable to patients whose weight or medical problems prevent them from exercise. Dr. Evans believes activating the PPARd pathway with drugs (one such experimental drug already is in development to treat people with lipid metabolism) or genetic engineering would help enhance muscle strength, combat obesity, and protect against diabetes in these patients.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Sarah Goodwin
Federation of American Societies for Experimental Biology

"Theoretically, energy bars produce more moderate increases and decreases in blood sugar levels than a typical candy bar," said Steve Hertzler, an associate professor of medical dietetics at Ohio State. "But these claims aren't necessarily valid." His study appears in a recent issue of the Journal of the American Dietetic Association.

Hertzler wanted to know how energy bars affected blood glucose levels. Glucose is a sugar that provides energy to the body's cells - for example, red-blood cells and most parts of the brain derive most of their energy from glucose.

"Athletes - especially those involved in endurance sports - want to enhance performance, and energy bars claim to help keep blood sugar levels at a moderate level," Hertzler said.

Volunteers had to fast for at least 12 hours before taking part in each of four experiments. Then, they ate one of four experimental "meals" consisting of either four slices of white bread; a Snickers bar; an Ironman PR Bar; or a PowerBar. Each experimental meal provided the same amount of carbohydrates (50 grams.)

Hertzler then tested the effects these foods had on blood glucose levels at 15-minute intervals for up to two hours after each experimental meal. The volunteers had to wait at least 24 hours between each experimental meal.

Hertzler measured each subject's blood samples for glucose levels, to determine which food most raised blood sugar levels.

Both energy bars caused blood glucose levels to peak at 30 minutes, while levels peaked at 45 minutes after the bread and candy bar were consumed. Blood glucose levels declined steadily throughout the duration of testing for all foods but the Ironman PR Bar. This bar caused blood glucose rates to remain fairly steady, probably because of the moderate carbohydrate level of the bar, according to Hertzler.

"Though blood glucose rates peaked at 30 minutes with both bars, the high-carbohydrate energy bar - the PowerBar - caused a much sharper decline," Hertzler said. "In fact, the decline was sharper than with the candy bar." Much of the energy derived from the bread and the candy bar came from carbohydrate and the same was true for the PowerBar. While the bar is low in protein and fat, more than 70 percent of it is made up of carbohydrate (such as high-fructose corn syrup; oat bran; and brown rice). In contrast, 40 percent of the Ironman PR is comprised of carbohydrate (high fructose corn syrup and fructose.) The rest of the bar was comprised of 30 percent fat and 30 percent protein.

"The composition of this bar may have been responsible for the diminished blood glucose response," Hertzler said. "Athletes involved in short-duration events who want a quick energy boost should eat a high-carbohydrate energy bar or a candy bar," he suggests. "However, endurance athletes would do well to consume an energy bar with a moderate carbohydrate level."

Hertzler conducted this study while at Kent State University in Kent, Ohio. He is continuing similar research at Ohio State.

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Article adapted by MD Sports Weblog from original press release.
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Contact: Steve Hertzler
Ohio State University

Editor's note: This research was funded by a grant from Kent State University. The researcher received no funding from either energy bar manufacturer.

In studies done with monkeys, which show menstrual cyclicity much like women, researchers showed that low energy availability associated with strenuous exercise training plays an important role in causing exercise-induced amenorrhea. These researchers, working at the University of Pittsburgh, published findings in the Journal of Clinical Endocrinology and Metabolism showing that exercise-induced amenorrhea was reversible in the monkeys by increasing food intake while the monkeys still exercised.

Williams worked with Judy L. Cameron, associate professor of psychiatry and cell biology and physiology at the University of Pittsburgh. Dana L. Helmreich and David B. Parfitt, then graduate students, and Anne Caston-Balderrama, at that time a post-doctoral fellow at the University of Pittsburgh, were also part of the research team. The researchers decided to look at an animal model to understand the causes of exercise-induced amenorrhea because it is difficult to closely control factors, such as eating habits and exercise, when studying humans. They chose cynomolgus monkeys because, like humans, they have a menstrual cycle of 28 days, ovulate in mid-cycle and show monthly periods of menses.

"It is difficult to obtain rigorous control in human studies, short of locking people up," says Williams.

Previous cross-sectional studies and short-term studies in humans had shown a correlation between changes in energy availability and changes in the menstrual cycle, but those studies were not definitive.

There was also some indication that metabolic states experienced by strenuously exercising women were similar to those in chronically calorie restricted people. However, whether the increased energy utilization which occurs with exercise or some other effect of exercise caused exercise-induced reproductive dysfunction was unknown.

"The idea that exercise or something about exercise is harmful to females was not definitively ruled out," says Williams. "That exercise itself is harmful would be a dangerous message to put out there. We needed to look at what it was about exercise that caused amenorrhea, what it was that suppresses ovulation. To do that, we needed a carefully controlled study."

After the researchers monitored normal menstrual cycles in eight monkeys for a few months, they trained the monkeys to run on treadmills, slowly increasing their daily training schedule to about six miles per day. Throughout the training period the amount of food provided remained the standard amount for a normal 4.5 to 7.5 pound monkey, although the researchers note that some monkeys did not finish all of their food all of the time.

The researchers found that during the study "there were no significant changes in body weight or caloric intake over the course of training and the development of amenorrhea." While body weight did not change, there were indications of an adaptation in energy expenditure. That is, the monkeys' metabolic hormones also changed, with a 20 percent drop in circulating thyroid hormone, suggesting that the suppression of ovulation is more closely related to negative energy balance than to a decrease in body weight.

To seal the conclusion that a negative energy balance was the key to exercise-induced amenorrhea, the researchers took four of the previous eight monkeys and, while keeping them on the same exercise program, provided them with more food than they were used to. All the monkeys eventually resumed normal menstrual cycles. However, those monkeys who increased their food consumption most rapidly and consumed the most additional food, resumed ovulation within as little as 12 to 16 days while those who increased their caloric intake more slowly, took almost two months to resume ovulation.

Williams is now conducting studies on women who agree to exercise and eat according to a prescribed regimen for four to six months. She is concerned because recreational exercisers have the first signs of ovulatory suppression and may easily be thrust into amenorrhea if energy availability declines. Many women that exercise also restrict their calories, consciously or unconsciously.

"Our goal is to test whether practical guidelines can be developed regarding the optimal balance between calories of food taken in and calories expended through exercise in order to maintain ovulation and regular menstrual cycles," says Williams. "This would then ensure that estrogen levels were also maintained at healthy levels. This is important because estrogen is a key hormone in the body for many physiological systems, influencing bone strength and cardiovascular health, not just reproduction."

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Article adapted by MD Sports Weblog from original press release.
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Contact: A'ndrea Elyse Messer
Penn State

“Decades of declining agricultural prices have been reversed thanks to the growing use of biofuels,” says Christopher Flavin, president of the Institute. “Farmers in some of the poorest nations have been decimated by U.S. and European subsidies to crops such as corn, cotton, and sugar. Today’s higher prices may allow them to sell their crops at a decent price, but major agriculture reforms and infrastructure development will be needed to ensure that the increased benefits go to the world’s 800 million undernourished people, most of whom live in rural areas.”

Biofuels for Transport, undertaken with support from the German Ministry of Food, Agriculture, and Consumer Protection, assesses the range of “sustainability” issues the biofuels industry will present in the years ahead, ranging from implications for the global climate and water resources to biological diversity and the world’s poor. The book finds that rising food prices are a hardship for some urban poor, who will need increased assistance from the World Food Programme and other relief efforts. However, it notes that the central cause of food scarcity is poverty, and seeking food security by driving agricultural prices ever lower will hurt more people than it helps.

Growth in biofuels production may have unexpected economic benefits, according to the experts who contributed to the report. Of the 47 poorest countries, 38 are net importers of oil and 25 import all of their oil; for these nations, the tripling in oil prices has been an economic disaster. But nations that develop domestic biofuels industries will be able to purchase fuel from their own farmers rather than spending scarce foreign exchange on imported oil.

Luke Jaeger was fed up with high fuel prices.

Jaeger and his wife Darcy farm with his family in the Clark County area, raising a variety of row crops, including wheat and sorghum. When Jaeger found just how little of their acreage could be devoted to an oil crop production and still meet his farm's energy needs, he knew that it was time for action.

"Dryland farmers, in western Kansas, if they would just put 1 to 2 percent of their farm acres to winter canola or sunflowers, they would have enough acreage to get diesel fuel to run their farm for the whole year," Jaeger said. He planted 60 acres of winter canola because it holds moisture in the soil, similar to sorghum, and because it can protect soil from erosion at even the early stages in its growth cycle. Also, canola seeds have higher oil content, about 40 percent, than other oil crops like sunflowers or soybeans, Jaeger said.

Bob Dinneen, President of the Renewable Fuels Association (the same association that claims displacement of 170 million barrels of oil with the energy equivalent of 64 million barrels of ethanol) wrote to Rolling Stone and addressed Jeff Goodell's recent story:

Letter To The Editor: Response to "The Ethanol Scam"

In the letter, Dinneen took a shot at me, writing "As is to be expected, Mr. Goodell relied on the figures of an energy blogger for his facts." Goodell defended me:

For a thorough clarification, check out oil industry engineer Robert Rapier's analysis. I know that Dinneen finds bloggers unsavory, but Rapier is among the most fair-minded and insightful critics of the energy industry I've come across.

And he pointed Dinneen here. So, Bob Dinneen, this one's for you. Let's deconstruct his letter. Jumping past the all too predictable ad hominems:

Wow, I am having to jump pretty far. Farther than I thought, as the letter is laced with ad hominems. Four paragraphs into the letter, Dinneen is waving the flag and talking about "Mr. Goodell's Hugo Chavez." Was this the best the RFA could come up with? Actually, I want to jump down and address the most egregious error, and the claim that I was most certain would be made by ethanol proponents:

Yet another common misconception offered by ethanol novices is that ethanol is at best energy neutral, meaning it takes as much energy to produce as it yields. As is to be expected, Mr. Goodell relied on the figures of an energy blogger for his facts. Inconveniently for his arguments, the federal government has different figures. According to the Argonne National Laboratories, ethanol yields nearly 70% more energy that it took to produce. Conversely, refined gasoline contains 20% LESS energy that it took to produce.

Can you count the errors and misleading statements? First, "ethanol yields nearly 70% more energy that it took to produce". Then "gasoline contains 20% LESS energy that it took to produce." Are you comparing like to like, Mr. Dinneen? Of course you aren't. By your gasoline metric, ethanol also contains less energy than it took to produce. Why? Because you are counting the crude oil feed as an "input" to the gasoline process, but you are not counting the crude ethanol feed as an input to the ethanol process. You are not comparing like to like; you are comparing an efficiency to an energy return. So, here's a question. If I give you some quantity of energy to invest in energy production, will you end up with more energy if you invest that into gasoline production, or into ethanol production? The answer is gasoline production, by a wide margin. And I have demonstrated that numerous times, using the pro-ethanol USDA's own numbers. I repeat: I am using pro-ethanol sources for my analyses. So accuse me of bias if you wish, but that doesn't change the numbers.

Which brings us to the claim of a yield of nearly 70% more energy than it took to produce. I wonder if Dinneen knows (or cares?) how the USDA paper arrived at this number. I am going to show you how they did, and cite the reports so you can check for yourself. I analyzed the reports in detail here, using their own numbers to show what they did. You can read the analysis for yourself, but here's the executive summary.

In 2002, the USDA reported on the energy balance of corn ethanol, stating that the energy balance was 1.34 units of energy out for every unit in. As I showed, they did a little accounting trick to get that, as the real number - when full BTU credit was taken for the animal feed by-products - was 1.27. Minor quibble, but it made me alert for more accounting tricks. And we got them in a report released 2 years later.

In their 2004 report, the USDA acknowledged that they had grossly underestimated a number of energy inputs in the 2002 report. So, they corrected those numbers. But some energy inputs had gone down, and at the end of the day, the energy inputs/outputs in the 2004 report were about the same as in the 2002 report. Yet in the 2004 report, they reported that the energy ratio for ethanol was 1.67, which is where Mr. Dinneen got his number.

Now, what was it really? Look at Table 3 in the 2004 USDA report. I will just produce it for you so you can see for yourself:

I know that's kind of hard to read, but here's what it says. (You can always check out the original if you think I am pulling any funny business). The energy produced in a wet mill process is only 2% greater than the energy it took to produce the ethanol. And I would point out that things like topsoil and aquifer depletion, energy to build the ethanol plant, etc. were not part of the analysis. (They said they didn't have good information, so they just omitted any attempt to account for it). For a dry mill process, they reported that the energy return is 1.10, 10% energy produced, and the weighted average of the two is 1.06. Those are the raw, unmanipulated numbers. In other words, input 1 BTU of fossil fuels, output 1.06 BTUs of ethanol. And given the subsidy for ethanol, it should be clear that this is actually a subsidy for fossil fuels, which is responsible for nearly all of ethanol's BTUs.

In Table 4, to the right, you can see the manipulated numbers, and the energy return of 1.67. So, how did they do that?

What they have done, is they have lowered the energy inputs into the ethanol process by a great deal. And the way they did that was to change their methodology. Instead of taking a credit for by-products, what they did was increase the energy alloted to the by-product. By doing this, they subtracted the energy inputs allocated to ethanol, and therefore manipulated the answer.

There is no reason that they couldn't have boosted the energy return to any number they wanted, just by allocating more and more of the energy inputs to the by-products. I could boost the energy return to infinity by allocating all of the energy inputs to the by-product. It makes the by-product energy return look horrible, but it artificially boosts the ethanol energy return. And they aren't reporting the by-product energy return, so you have to pay close attention to see exactly what they did.

Dried distillers grain (DDGS) has become a good dumping ground for the ethanol industry's claims. When you point out that the energy balance is poor, they take a BTU credit for DDGS, just as if you could put in in your car and drive. But they have now figured out that they place more of the "blame" of energy of production into the DDGS and exaggerate the energy return for ethanol. But you can't have it both ways. If the energy of production gets dumped into DDGS, it suddenly becomes a by-product with an incredibly high energy cost to produce.

Bottom line: Playing with the numbers doesn't change the fact that ethanol production is marginally above energy neutral. Despite Mr. Dinneen's claim that this is a "misconception offered by ethanol novices", it is in fact true, based on the USDA's own numbers. Mr. Dinneen and those who repeat the 1.67 number are either misinformed, or purposely misleading the public.

Mr. Dinneen concludes with:

It is entirely appropriate to have a debate about our energy policy in this country.

I agree. Here's my proposal. Three rounds, 2,000 word limit per round, with the debate hosted here, at your site, and at The Oil Drum. I suggest the debate resolution: "Corn Ethanol is Responsible Energy Policy." I will take the negative. If you have an alternate proposal, I would be glad to entertain it.

References

1. Shapouri, H., J.A. Duffield, and M. Wang. 2002. The Energy Balance of Corn Ethanol: An Update. AER-814. Washington, D.C.: USDA Office of the Chief Economist.

2. Shapouri, H., J.A. Duffield, and M. Wang. 2004. The 2001 Net Energy Balance of Corn Ethanol. Washington, D.C.: USDA Office of the Chief Economist.

Ethanol: A Few Myths Debunked

To be honest, there are so many misconceptions and myths in the article that a better name for it would have been Ethanol: A Few Myths Repeated. I think all of these "myths" have been covered at one time or another in this blog, but he does quote Vinod Khosla at length. So, this might be a good time to re-debunk Khosla, given that he has repeated this claims many times since the first debunking.

So, once again, here are Vinod Khosla's claims, repeated from the above article, dissected and debunked.

VK: Energy balance is not even the right question to answer. It is not the energy balance of ethanol that matters but the energy balance of ethanol relative to the energy balance of gasoline.

I agree 100%. But this is exactly the comparison that I and others have consistently made. The problem is that VK is comparing apples to bananas, as I will show.

VK: Dr. Wang at Argonne National Labs has built one of the most rigorous and transparent public models for energy balance calculations. His results indicate that corn ethanol has almost twice the energy balance compared to gasoline, yet this crucial fact is seldom mentioned in the press.

That’s because it is just flat-out wrong. If this was true, we wouldn’t even use gasoline, and ethanol wouldn’t need federal subsidies. After all, why on earth would we invest our BTUs into gasoline when we could get twice the energy return with ethanol? The reason is that VK is grossly misinformed, but he has no excuse because I have explained this to him over the phone. Twice.

VK: According to the majority of studies, corn ethanol has an energy balance between 1.3-1.8 while gasoline is substantially worse, at about 0.8 (since it takes energy to extract, transport, refine and handle gasoline).

Doesn’t it take energy to plant and harvest corn, ferment the ethanol, refine it, and transport it? Of course it does. Except with gasoline, the planting and fermenting have already been done by nature. The harvesting involves drilling a hole in the ground and extracting an energy rich, water-insoluble mixture that takes a fraction of the energy to refine that ethanol takes.

Here is the true story. If I have 1 BTU to invest, and I want a return on that BTU, where am I going to invest it to get the most value? Well, if I invest in ethanol - according to studies that the afore-mentioned Dr. Wang has co-authored - I am going to end up with about 1.06 BTUs of fuel and 0.25 BTUs worth of animal feed. So, for an investment of 1 BTU, I netted 0.06 BTUs of liquid fuel. Again that is backed up by the USDA’s own studies that Dr. Wang has co-authored.

If I invest that BTU into gasoline production, here is what I get. The worst conventional fields in the world have a 10/1 energy return on getting crude oil out of the ground. According to Cutler Cleveland (and consistent with my own personal experience), the world wide average energy return for crude oil extraction is 17/1. So, for my 1 BTU investment, I average 17 BTUs of crude in the crude tank. But I have to refine it. A heavy, sour refinery has an energy return of about 10/1 (producing gasoline, diesel, heating oil, jet fuel, etc. from the crude). So, my 17 BTUs of crude are going to take 1.7 BTUs – in the worst case – to refine. I have then invested 2.7 BTUs (1 to extract and 1.7 to refine) to process 17 BTUs of crude into liquid fuels.

Typically, there are losses of around 5% in refining crude. These losses often have BTU value that is recovered, but let’s say they don’t. Then, my gross is 17 * 0.95 = 16.15 BTUs of usable liquid fuels for my BTU investment of 2.7 BTUs. My energy return is 16.15/2.7, or 5.98. This compares to an energy return of 1.3 for ethanol (when we count animal feed as BTUs). So, gasoline has about 4.6 times the energy balance of ethanol, as opposed to VK’s claim of twice the energy balance for ethanol. He is off by an order of magnitude. Now it should start to become clear why ethanol will always need subsidies to compete.

Moving on:

VK: Electricity has an energy balance four times worse than corn ethanol. Do we stop using electricity?

No, because we can’t plug our toasters into a pile of coal. We can, however, run vehicles on the fossil fuel inputs that we used to make ethanol. That is the key difference. Electricity is a much more user-friendly form of energy than is coal. There is no advantage to recycling fossil fuels into ethanol (well, there’s coal, but I won’t go there).

VK: Dr. Wang goes on to say that energy balance is “not a meaningful number for any fuel in evaluating its benefits. "Why then does the press continue mentioning it?

It is ironic that in the same essay VK argues that the energy balance of ethanol is twice that of gasoline, he also argues that it is not a meaningful question. I have pointed out the absurdity of this position before, because this isn’t the first time he has taken it.

VK: Why do they fail to mention that electricity has a substantially worse energy balance than ethanol?

See above. Think about plugging your DVD player into a pile of coal and the picture will start to become clear.

VK: What is often inferred by the press is that it takes more petroleum to make ethanol than is displaced. This is emphatically NOT true, even in the most vintage of plants.

He is correct here, but fails to mention that the majority of the fossil fuel input into an ethanol plant, natural gas, works just fine as a vehicle fuel. Compressed natural gas (CNG) buses are very popular mass transit options, for instance.

VK: In fact if we have to pick an alternative to gasoline, then ethanol is the best choice today.

Ethanol, also known as recycled natural gas. My question is: Why go to the trouble of recycling the natural gas into ethanol, when CNG buses have a proven track record?

VK: Energy balance is the wrong question. Greenhouse gas emissions per mile driven is the right question.

Those questions go hand in hand. In fact, they are inversely proportional. The lower the energy balance, the higher the overall greenhouse gas emissions for the process. For an energy balance of 1.06, you have a 6% reduction in greenhouse gas emissions. Along with that, we get more pesticide and herbicide runoff into our waterways, increased soil erosion from expanded corn production, and we all get to pay more for our food.

We can do better. If we put half the effort into supporting conservation measures that we do into supporting corn ethanol, we could make a significant reduction in our fossil fuel usage. But, there isn’t any money to be made in that, so this option tends to be ignored. Sooner or later we won’t have a choice, but I would like to see us make the choice while we do still options.

Dr. Wang was clearly miffed about my usage of “sleight of hand.” While I do not consider usage of this phrase insulting, I felt like the right thing to do was to apologize since Dr. Wang took offense. So, I e-mailed back to Dr. Wang, Tom (who never again responded) and Mr. Khosla. Again, my comments are in blue, Dr. Wang's are in green, and Mr. Khosla's are in red:

Dear Tom, Dr. Wang, and Mr. Khosla:

First of all, let me apologize for the offense you took at my usage of "sleight of hand." Never in my life have I considered that phrase insulting, but clearly you were insulted by it. I have used that term on many occasions, and had that term used against me. For me, it just means that things are not as they appear to be. So please do not presume that I was being intentionally insulting, because I was not.

Second, I have been stunned at the response from publishing our exchange. Between my R-Squared blog and The Oil Drum, the exchange received well over 400 responses to date, and I got around 200 e-mails. And while you may consider me combative and stubborn, I am also open-minded and very analytical. I engage in this discourse as much to learn as to convey information, and I was able to understand through those responses just why people are so confused about this issue of gasoline efficiency versus ethanol efficiency.

The reason I am engaged in this debate is that it is very important to me that we pursue the correct energy policy. While I have argued in favor of certain solutions, I have also spent a lot of time debunking certain claims. I don't believe we do ourselves any favors, nor do we help ourselves make educated decisions by allowing myths to persist.

I agree with Mr. Khosla that maybe there are other questions that are better asked. We can debate many different angles over whether or not we should be advocating ethanol from corn. But this particular point of contention is about whether the claim "the efficiency of producing ethanol is better than the efficiency of producing gasoline" is accurate. I have lost count of how many times I have heard some variation of this claim. Tom, in your initial response to me, you included an attachment which made the claim:

"As you can see, the fossil energy input per unit of ethanol is lower--0.74 million Btu fossil energy consumed for each 1 million Btu of ethanol delivered, compared to 1.23 million Btu of fossil energy consumed for each million Btu of gasoline delivered."

That is simply a false claim. Dr. Wang will probably acknowledge that this claim as written is incorrect, and yet it is derived from his work. That is why I say people are being misled as a result of his work. Perhaps it is unintentional, but when people make a claim such as the one above, they have misinterpreted what is being said, and used this misinterpretation to promote the ethanol agenda.

The real critical point when comparing the two processes is to make sure the boundaries are drawn in exactly the same place and definitions are consistent. When this is done it becomes clear why the above claim as written is incorrect. But please don't misinterpret this into thinking that I am trying to completely rebut all ethanol arguments. I am addressing a single issue.

Again, please accept my sincere apologies for offending you. That was not my intent.

Sincerely,

Robert Rapier<