Production of biofuels from raw materials requires energy (for farming, transport and conversion to final product, and the production / application of fertilizers, pesticides, herbicides, and fungicides), and has environmental consequences.[28]
The energy balance of a biofuel (sometimes called "Net energy gain" and EROEI) is determined by the amount of energy put into the manufacture of fuel compared to the amount of energy released when it is burned in a vehicle. This varies by feedstock and according to the assumptions used. Biodiesel made from sunflowers may produce only 0.46 times the input rate of fuel energy.[29] Biodiesel made from soybeans may produce 3.2 times the input rate of fossil fuels.[30] This compares to 0.805 for gasoline and 0.843 for diesel made from petroleum.[31] Biofuels may require higher energy input per unit of BTU energy content produced than fossil fuels: petroleum can be pumped out of the ground and processed more efficiently than biofuels can be grown and processed. However, this is not necessarily a reason to use oil instead of biofuels, nor does it have an impact on the environmental benefits provided by a given biofuel.
Studies have been done that calculate energy balances for biofuel production. Some of these show large differences depending on the biomass feedstock used and location.[32]
To explain one specific example, a June 17, 2006 editorial in the Wall. St. Journal stated, "The most widely cited research on this subject comes from Cornell's David Pimental and Berkeley's Ted Patzek. They've found that it takes more than a gallon of fossil fuel to make one gallon of ethanol — 29% more. That's because it takes enormous amounts of fossil-fuel energy to grow corn (using fertilizer and irrigation), to transport the crops and then to turn that corn into ethanol."[33]
Life cycle assessments of biofuel production show that under certain circumstances, biofuels produce only limited savings in energy and greenhouse gas emissions. Fertilizer inputs and transportation of biomass across large distances can reduce the greenhouse gas (GHG) savings achieved. The location of biofuel processing plants can be planned to minimize the need for transport, and agricultural regimes can be developed to limit the amount of fertiliser used for biomass production. A European study on the greenhouse gas emissions found that well-to-wheel (WTW) CO2 emissions of biodiesel from seed crops such as rapeseed could be almost as high as fossil diesel. It showed a similar result for bio-ethanol from starch crops, which could have almost as many WTW CO2 emissions as fossil petrol. This study showed that second generation biofuels have far lower WTW CO2 emissions.[34]
Other independent LCA studies[citation needed] show that biofuels save around 50% of the CO2 emissions of the equivalent fossil fuels. This can be increased to 80-90% GHG emissions savings if second generation processes or reduced fertiliser growing regimes are used.[citation needed] Further GHG savings can be achieved by using by-products to provide heat, such as using bagasse to power ethanol production from sugarcane.[35]
Collocation of synergistic processing plants can enhance efficiency. One example is to use the exhaust heat from an industrial process for ethanol production, which can then recycle cooler processing water, instead of evaporating hot water that warms the atmosphere.[36]
Biomass planting mandated by law (as in European Union) results in large quantities of biomass being transported to EU from Africa, Asia and Americas (Canada, USA, Brazil).[37] For example in Poland as much as 85% of biomass used is imported from outside of EU,[38] with single electric plant in Łódź importing over 7'000 tons of wood biomass from Republic of Komi (Russia) over distance of 7'000 kilometers on monthly basis.[39]
T. A. Kiefer of the US Air Force Air War College, in a paper entitled "The False Promise of Liquid Biofuels", laid out factors that preclude biofuels from replacing petroleum as a national-scale transportation fuel. Kiefer states “The energy content of the final-product biofuel compared to the energy required to produce it proves to be a very poor investment, especially compared to other alternatives. In many cases, there is net loss of energy." He concludes “...pursuit of biofuels creates irreversible harm to the environment, increases greenhouse gas emissions, undermines food security, and promotes abuse of human rights." [40]