Ethanol biomass is organic material which is suitable to the production of ethanol. Corn is a notable and widely used example of this, but other sources can include algae, switchgrass, and other cellulosic crops. Sourcing biomass is a concern for some ethanol producers, as they need access to materials which are energy dense and can be converted into ethanol efficiently. In some circles, biomass sourcing is a subject of contentious debate.
The term “biomass” refers more generally to organic material, classically waste material which cannot be eaten or used in industrial processes. The term is also used in ecology to talk about the total plant material in a given area, with biomass being a concern as well as biodiversity. Ethanol biomass can in fact be used in industrial processes, and some sources of biomass are actually sources of food as well.
To make ethanol, the biomass has to be converted so that its energy is available in the form of a fuel which people can use. Ethanol production relies on using ethanol biomass which requires less energy to grow and convert than it produces. Otherwise, the process would be inefficient, making ethanol a poor choice of alternative fuel. Crops like switchgrass are good candidates because they require far less energy to grow, and the technology for refining ethanol biomass to turn it into ethanol is improving all the time, increasing the efficiency with which ethanol can be extracted.
Some people have suggested that by treating edible food crops like corn as ethanol biomass, the ethanol industry could potentially jeopardize the stability of the food supply, as farmers might be more inclined to plant food crops for use in ethanol production. Non-food crops utilized as ethanol biomass could also theoretically supplant food crops, reducing the available food on the market. However, ethanol advocates believe that such imbalances can be avoided with thoughtful land management, and that the production of ethanol biomass does not need to impinge on food production.
A secondary issue with ethanol energy is that many governments heavily subsidize the production of ethanol biomass. Critics suggest that subsidies have propped up an artificial market, and that removing the subsidies would allow people to see whether or not there is really a market for ethanol. Advocates point out that similar subsidies are in place for many crops and industries, and that sometimes subsidies are needed to support a nascent industry until it can achieve independence. Under this theory, the need for subsidies would gradually decline as ethanol production and the demand for ethanol increased.