While corn and oil seeds will continue as dependable, renewable sources for manufacturing ethanol and biodiesel in the future, these well-known crops will likely share the stage with other plants destined for energy greatness.
The ultimate technology to shape and mold long-term plant-based energy production is either in development, or hasn't been invented yet, according to Stephen Kaffka, an extension agronomist with the University of California, Davis (UCD).
“The plant species to be used will be subject to work by molecular biologists, agronomists, and plant breeders,” Kaffka said. “We're not clear what the best species will be or the nature of that plant, but it will likely be transformed in the future.”
That's the snapshot for renewable fuels, according to Kaffka, who has his pulse on producing improved plants in California for biofuels production.
Kaffka is the director of the UCD Long Term Research on Agricultural Systems Project, at the Russell Ranch, located between Winters and Davis, Calif. The project is part of UCD's Agricultural Sustainability Institute where a long-term, large-scale experiment is underway to evaluate the impact of biofuels feedstock production in semi-arid and Mediterranean soils.
“We will add new biofuel treatments this year, emphasizing the removal of larger amounts of carbon from soils than before. The 14-year project will provide empirical, experimental data for evaluating the consequences of removing more carbon from soils than in the past.”
Kaffka's research has focused on oil seeds, sugar, and natural precursor feed stocks for ethanol and biodiesel. His interest also lies in salinity management, working to grow more salt tolerant crops like sugar beets and safflower within salty water that should be evaluated for use in generating ethanol.
“Corn for ethanol development is here to stay,” Kaffka said. “Corn is grown in large amounts with high efficiency — it's easy to handle, it's dried, and can be stored and shipped readily. Corn is a concentrated little nugget of starch that is energy. Farmers can feed the distiller's grain coproduct to cattle.”
“Since California has the largest dairy herd in the nation, corn-based ethanol plants in California remain a good idea. I've come to the conclusion that plant-based fuels address a serious need and have a serious prospect for continuity in the future.”
Currently, most of the corn used in California ethanol plants is railed in from other states.
Oil seeds also have a continued bright horizon for biodiesel. Perks of oil seed-biodiesel include easy manufacturing and a higher energy return on investment compared to corn ethanol starch. Oils are easily converted into diesel or other liquid fuels.
It's a better match for smaller companies interested in less complicated technology and less capital-intensive outlays, Kaffka said.
In California, there's a great deal of scrambling in the biofuels industry to lock down sources of waste grease and plant production.
“These biofuels companies would love to have oil seeds produced within California, or nearby, at a low enough price to make them suitable feed stocks.”
Other crops holding promise are sugarcane, sugarbeets, and grain sorghum. Europe is currently utilizing wheat, barley, and sugarbeets as ethanol sources.
Cellulosic ethanol is a biofuels industry buzzword regarding production of ethanol from grasses and agricultural wastes versus feedstocks.
“An important fact about grasses and straws is that the cellulose in the plant wall must be broken down to its component sugars. There's a terrific amount of effort underway on how to efficiently do that. Currently the cost to achieve this is much greater than making ethanol from corn or biodiesel from oil seeds. We haven't had the breakthrough there yet.”
Growing Bermudagrass in saline soils with wastewater for cattle grazing in the San Joaquin Valley (SJV), is another Kaffka project. “Bermudagrass and other salt tolerant grasses could work as feed stocks once cellulosic technologies are worked out.”
“Switchgrass, a native perennial from the prairie states, is the grass most commonly mentioned for ethanol production. Because switchgrass is not grown in California, we don't know yet if the grass could efficiently be grown here,” Kaffka said.
Another possible grass source for ethanol is a 10 to 12-foot tall perennial called miscanthus. While generally grown in colder climates, miscanthus dies back in autumn, and the nutrients are returned to the crown. The dry matter is cut off once a year. Europe has been conducting experiments with miscanthus for almost a decade.
“What I'm trying to push is the idea of using salt-tolerant grasses to use salty water in the SJV and elsewhere to help reduce the amount of salty water we have to manage,” Kaffka said.
“In my view, combining the solution of one environmental problem with biomass production for energy makes complete sense in the West. There is a large amount of waste water that might be used for biomass production.”
Alfalfa is sometimes discussed as a potential cellulosic energy source packed with advantages. It's readily fermentable with low amounts of resistant lignin compounds, and doesn't require high-energy nitrogen input costs.
In California, alfalfa for energy production could conflict with other needs, since the state is alfalfa deficient due to the dairy industry's feed demands.
Other factors that will impact future plants for fuels include public policy and the price of oil.
“Unless there is a major policy change on ethanol, related subsidies, and import restrictions — the growth of corn-based ethanol production will continue in the U.S. as the primary source of alternative transportation fuels.”
Kaffka believes policies such as the 2007 farm bill will send a signal to the renewable fuel industry on where to make investment decisions.