Background
Fuel ethanol is an alternative fuel derived from a biologically renewable resource that can also be used as an
octane enhancer and oxygenate. With society's growing concerns about environmental issues and hazardous pollutants,
this environmentally beneficial fuel is gaining increasing attention and support. It provides excellent opportunities
for Canadian agriculture, and can contribute to achieving energy self-reliance for Canada. Ethanol produced in
Ontario is, at present primarily made from grain corn.
Many questions have been raised as to the net energy efficiency of ethanol production from corn. Over the last
decade, much progress has been made in terms of energy-efficient ethanol production methods.
Ethanol contains about 22,400 (high heating value) BTUs per litre. The energy content, however, may not be as important as the energy replaced. Due to the higher combustion efficiency of ethanol and its octane credit at the refinery, for example, ethanol can replace 26,575 BTU of gasoline (Levelton Engineering Ltd. and (S&T)2 Consulting Inc.).
Using the displacement value for calculating the energy content of co-products, there is a further 3,720 BTU/litre of energy in ethanol represented by the co-products. The total energy represented b a litre of ethanol is therefore 30,290 BTU. It takes about 4,700 BTU of energy to grow the corn required for one litre of ethanol. This is about 15.5% of the energy in the ethanol and the co-product. It takes a further 13,300 BTU (43.9%) of the energy in the ethanol) to process the corn to ethanol using current technology and practices. It is expected that fully optimized plants will be able to lower this to 10,600 BTU (35.0%) in the near future.
If corn farmers use state-of-the-art, energy efficient and sustainable
farming techniques and ethanol plants integrate state-of-the-art production processes, the amount of energy contained
in the ethanol and its co-products can be more than twice the energy used to grow the corn and convert it into
ethanol.
Determining Energy Balance
Three areas need to be considered when determining the energy balance of ethanol:
Energy to grow the raw material
The amount of energy needed to grow corn depends on the farming practices and conditions. Fertilizer is the largest energy input into corn production, and its use varies dramatically. Other areas of energy input are corn drying, seed corn production, on-farm electricity, bulk crop transportation and crop irrigation, although this is rarely used for grain corn production in Ontario. Since 1975, energy use per tonne of crop has decreased by 50% in Ontario. Technological improvements in corn production will continue to improve the net energy balance of production. Good examples of this are increasing yields of corn from genetically engineered varieties and reducing soil tillage for crop production, significantly reducing energy inputs and enhancing soil conservation.
Energy used to manufacture ethanol
Ethanol production efficiency has greatly improved over the last decade. The technology is becoming increasingly energy efficient. Energy use in dry milling is about equivalent to that of wet milling, the two primary manufacturing methods used to produce ethanol.
Allocation of energy use between ethanol and other co-products
In order to determine the energy balance of ethanol production, it is important to take into consideration that the production of valuable co-products also requires some of this energy. Therefore, the amount of energy consumption of the process needs to be allocated between ethanol and the other co-products. However, even without giving credit to the co-products generated from ethanol production, the net energy balance is positive.
Some of the most comprehensive research from the Institute of Local Self-Reliance indicates that using state-of-the-art farming and production methods, "the amount of energy contained in a gallon of ethanol is more than twice the energy used to grow the corn and convert it to ethanol." It has been suggested that ethanol production from cellulosic crops will be even more energy net positive. Another comprehensive, but more conservative, study conducted by the U.S. Department of Agriculture, indicated that nearly 25% more energy is yielded by ethanol than is required to grow the corn and manufacture the ethanol.
| Summary of Energy Inputs and Outputs According to the 1995 study produced by the Institute for Local Self-Reliance, using state-of-the-art farming and ethanol production techniques would result in the following energy balance: |
||
|
INPUTS |
BTU's/Litre of Ethanol |
|
|
INPUTS - FEEDSTOCK |
||
| Fertilizer |
1,022 |
|
| Pesticides |
107 |
|
| Fuel |
349 |
|
| Irrigation |
1,597 |
|
| Other |
825 |
|
| Total |
3,901 |
|
|
INPUTS - PROCESSING |
||
| Process Steam |
6,917 |
|
| Electricity |
1,360 |
|
| Bulk Transport |
211 |
|
| Other |
277 |
|
| Total |
8,766 |
|
| TOTAL ENERGY INPUT |
12,667 |
|
|
OUTPUTS |
||
| Energy in Ethanol |
22,217 |
|
| Co-product Credits |
9,579 |
|
| TOTAL ENERGY OUTPUT |
31,796 |
|
| NET ENERGY GAIN |
19,130 |
= 151% |
Where can I get more Information?
Canadian Renewable Fuels Association
90 Woodlawn Rd. W.
Guelph, Ontario N1H 1B2
Telephone: (519)-767-0431
Fax: (519)-837-1674
E-mail: publicinfo@greenfuels.org
Rev. 1/12/2000