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Net Energy List (EROEI) Comparing Different Energy Processes
[EDITOR'S NOTE:
The authors of the report use the term EROI which is Energy Return On
Investment - a shorter but identical concept to EROEI. Any figure that
is less than 1.0 shows a net "loss" of energy. Break even for EROEI is
1.0. The figure 0.8, for example, would mean a net energy loss of 20%.
That is, it would take 20% MORE energy to acquire (or produce) the
energy than you would get by using it...NOT a good deal. Look at
1940's Oil and gas - it shows an EROEI of greater than 100 for
discoveries, which means that at the well head (where the oil comes out
of the ground), the energy returned by the oil was more than 100 TIMES
the energy it took to extract it...a VERY GOOD deal!]
| PROCESS |
EROI | |
Nonrenewable | | Oil and gas (domestic wellhead) |
|  | | 1940's |
|
Discoveries > 100.0 | | 1970's |
Production 23.0, discoveries 8.0 | | Coal (mine mouth) |
| | 1950's |
80.0 | | 1970's |
30.0 | | Oil shale |
0.7 to 13.3 | | Coal liquefaction |
0.5 to 8.2 | | Geopressured gas |
1.0 to 5.0 | |
Renewable | | Ethanol (sugercane) |
|
0.8 to 1.7 | | Ethanol (corn) |
|
1.3 | | Ethanol (corn residues) |
|
0.7 to 1.8 | | Methanol (wood) |
|
2.6 | | Solar space heat (fossil backup) |
|
| | Flat-plate collector |
|
1.9 | | Concentrating collector |
|
1.6 | |
Electricity Production | | Coal |
|
| | U.S. average |
|
9.0 (27.0) | | Western surface coal |
|
| | No scrubbers |
|
6.0 (18.0) | | Scrubbers |
|
2.5 (7.5) | | Hydropower |
|
11.2 (33.6) | | Nuclear (light-water reactor) |
|
4.0 (12.0) | | Solar |
|
| | Power satellite |
|
2.0 (6.0) | | Power tower |
|
4.2 (12.6) | | Photovoltaics |
|
1.7 (5.1) to 10.0 (30.0) | | Geothermal |
|
| | Liquid dominated |
|
4.0 (12.0) | | Hot dry rock |
|
1.9 (5.7) to 13.0 (39.0) |
Table Notes: Estimates of energy return on investment (EROI) ratios for
some existing and proposed fuel supply technologies. Numbers in
parentheses for electricity generation include a quality factor based
on a heat rate of 2646 kcal/kWh.
If you are a mathematician and
would like to see some of the theory behind this, here is a PDF of a
paper entitled: "Aggregation and the role of energy in the economy" by
Cutler J. Cleveland, Robert K. Kaufmann, and David I. Stern. [download - 184kb]
Energy Yield Ratio List
from
Environmental Accounting, Emergy, and Decision Making
Howard T. Odum
(John Wiley, 1996)
[EDITOR'S NOTE: Odum has created the term "emergy". He explains it as:
Emergy
(spelled with an "m") evaluates the work previously done to make a
product or service. Emergy is a measure of energy used in the past and
thus is different from a measure of energy now. The unit of emergy
(past available energy use) is the emjoule to distinguish it from
joules used for available energy remaining now. Scienceman describes
emergy as energy memory (Odum, 4, 6, 10; Scienceman, 9, 10)*.
Richard Heinberg describes Odum's "emergy" as "embodied energy".]
| ITEM |
ENERGY YIELD RATIO | |
Dependent Sources, No Emergy Yield | | Farm windmill, 17 mph wind |
|
0.03 | | Solar water heater |
|
0.18 | | Solar voltaic cell electricity |
0.41 |
|
| |
Fuels, Yielding Net Emergy | | Palm oil |
|
1.06 | | Energy-intensive corn |
|
1.10 | | Sugarcane alcohol |
|
1.14 | | Lignite at mine |
|
6.8 | | Natural gas, offshore |
|
6.8 | | Oil Mideast purchase |
|
8.4 | | Natural gas, onshore |
|
10.3 | | Coal, Wyoming |
|
10.5 | | Oil, Alaska |
|
11.1 | | Rainforest wood, 100 years growth |
|
12.0 |
|
|
| |
Sources of Electric Power, Yielding Net Emergy | | Ocean-thermal power plant |
|
1.5 | | Wind electro-power |
|
2-? | | Coal-fired power plant |
|
2.5 | | Rainforest wood power plant |
|
3.6 | | Nuclear electricity |
|
4.5 | | Hydroelectricity |
|
10.0 | | Geothermal |
|
13.0 | | Tidal electric, 25 ft. tidal range |
|
15.0 |
* - source: Emergy Evaluation,
Howard T. Odum, May 27, 1998. Environmental Engineering Sciences,
University of Florida, Gainesville, 32611; this paper was presented at
the International Workshop on Advances in Energy Studies: Energy flows in ecology and economy, Porto Venere, Italy, May 27,1998.
A PDF of this paper is avilable here.
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Net Energy List 
