1. Energy Inputs:by global IGC
   

1. Fertilizer

    Primarily containing nitrogen, phosphorous, potassium, calcium, sulfur, and magnesium, organic and inorganic fertilizers are key components in investigating corn ethanols net energy balance.  As an integral energy input in the production of corn, fertilizers are used for enriching soils with nutrients necessary for plant growth.  In a study comprised of the nine largest states that produce corn for the use of corn ethanol fuel, the U.S. Department of Agriculture examined the net energy used for producing a bushel of corn for the use of ethanol.  Measured in Btu’s per bushel, with farmers primarily using nitrogen, phosphate, potash and lime, it is observed that a total of 26,394 Btu/bushel of energy is required for production of fertilizers used on corn fields in the nine largest producers of corn in the United States (IL, IA, IN, NE, MN, MI, WI, OH and SD).

 

2. Herbicides/Pesticides

    Also an important component to corn production is the use of herbicides and pesticides.  Used for the reduction and removal of pest plants and animals, herbicides and pesticides interact with a plants or other organisms hormonal or other systems (roots) to kill the plant.  In a similar study conducted by the U.S. Department of Agriculture, for the production of corn in the nine largest corn producing states, the energy used for the production and distribution on corn crops of herbicides and pesticides 180,000 Btu/bushel.

    While the use of such chemicals is necessary for growing corn used for ethanol fuel, environmental hazards are posed by these substances.  Most commonly caused by surface runoff and leaching of chemicals in ground and residing water near farmland, such an influx can cause environmental problems such as algae blooms or eutrophication.  Not only does such a event kill of fish populations, but it also hazardous to humans.

3. Machinery 


Harvester -www.cornishfarmhouse.co.uk/harvester.jpg

The corn grown in the fields needs to be harvested and transported before conversion into Ethanol. This involves the use of heavy machinery, which uses energy. Ted Patzek notes “trucks, tractors, ploughs, cranes… barges, ships, etc…” must be replaced periodically (2006). Various studies reported an energy cost of infrastructure between 68 and 168 MJ/kg of hardware (Patzek 2006). Pimentel assigns 55kg of hardware per hectare of corn (1991). Machinery does need to be replaced, but not very often, meaning marginal machinery costs, mainly maintenance and fuel, would be much lower. It seems that once Ethanol’s infrastructure is in place, it could last for quite some time. Energy use in machinery would likely be high at first as the machinery is made, then be low for several years, and the machines are only fueled. There would be small spikes when existing machinery would need to be replaced or fixed. Finally, much of the existing infrastructure for gasoline can be used with ethanol, with minor adjustments to certain incompatible metals, which corrode under ethanol (Department Of Energy 2006). This would also keep costs down, because less new infrastructure would be required.

4. Transportation
Transportation of both the corn and the inputs to corn production also consumes energy. The total energy estimate for transportation costs is 400 Mj/hectare (Patzek 2006). Fertilizer, irrigated water, corn, and finally, the refined ethanol all need to be transported, all requiring energy. These transportation energy costs would likely fall over time. As the Ethanol infrastructure becomes more established, it would likely become more efficient. Farms would get larger, commutes would become shorter, and energy use in transportation would be minimized. Current ethanol fields are also spread across many states. The following graph of Ethanol Production Capacity using data from the Renewable Fuels Association shows the room for consolidation (2005).

We have also counted irrigation in transportation energy, because it is transport of water. It should be noted that only 15% of all ethanol corn is irrigated (Patzek 2006). Taking account of water use per acre, water depth, and pump efficiency, estimates on the energy use in irrigation are around 130 Mj/hectare (Patzek 2006).



Irrigation would likely consume more energy as ethanol production expands, because it is difficult to make irrigation more efficient. Moving the inputs of ethanol and ethanol itself consumes a large amount of energy.

5. Refining
Finally, once ethanol reaches an ethanol plant, it must be refined.