Minnesota has long been a leader in renewable energy. We were one of the initiators of the wind power revolution and are currently number three in total capacity, behind only the much larger states of Texas and California. Minnesota’s leadership on this issue has paid off handsomely and wind power is now widely accepted across the entire political spectrum. Even conservative Texan oilman T. Boone Pickens announced a huge investment into wind power.
However wind power is not the only source of the renewable energy from the farmlands. The plant and animal products from the farm are also stores of energy and can be used to deliver power. Burning plant and animals materials produces carbon dioxide like burning oil or coal but there is one big difference. Unlike burning coal or oil, burning plant material recycles the carbon and does not increase to the total amount of carbon dioxide the atmosphere. Therefore energy from plant and animal material, often referred to as biomass, is considered renewable energy.
Fuel from Biomass: Corn-based ethanol
Biomass for energy is currently out of favor because of the challenges that arose from using corn-based ethanol as a fuel for transportation. Corn based ethanol was the first large scale use of biomass for energy. Even though it works, problems arose from its widespread use. Most technical studies showed that overall carbon dioxide emissions were not reduced. Secondly there are growing concerns that using corn for fuel adversely affects the food-supply. Finally corn-based ethanol is proving too expensive to be viable. Even with record high oil prices and a substantial tax subsidy, the price of corn has risen so much that corn-based ethanol companies are not making money.
Given all the problems with corn based ethanol the EPA even considered rescinding the federal ethanol mandate. Minnesota had gone further than the federal government in encouraging corn-based ethanol and our state became the leader in ethanol use. Minnesota now has the largest E85, 85% ethanol blend, distribution network for flex fuel cars. In the long run we stand to benefit from the ethanol distribution infrastructure as new ethanol technologies come into play. But for now using food crops to make liquid fuels is not the only way to get energy from biomass. Waste biomass can also be directly burnt to generate electricity. And Minnesota can also lead in biomass based electricity.
Biomass Electricity in Minnesota
As far back as 1994 Minnesota Legislation passed a comprehensive bill that included requirements for the construction of small biomass powered electric power plants. There are several small electric power plants in Minnesota that use biomass as fuel, the largest one being an 110MW Xcel plant that uses forestry residue. However Minnesota has enough biomass resources to generate a much larger portion of our electricity.
A few years ago the Xcel Renewable Fund with the approval of the Public Utilities Commission funded a very comprehensive study about the availability of biomass in Minnesota. The study was performed by the Minneapolis based nonprofit Center for Energy and Environment. The report released last year covers the entire gamut of biomass in Minnesota from turkey manure to softwood timber. Based on the numbers from this study corn stalk is the one biomass resource that stands out above others. There are two reasons, a lot of corn is already being grown in Minnesota and there is no critical alternate use for corn stalk.
Advantages of using corn stalk for electricity
Corn stalk (also called corn stover) is the residue of the plant that is left over when the grain is harvested. Typically most of the corn stalk is tilled back into the land to maintain soil quality. Studies done by Oak Ridge National Laboratory have shown that about 40% to 60% of the corn stalk can be removed from the land without long term soil degradation. Corn is farmed on such a large scale that even half of the corn stalk in Minnesota can fuel 20% of our electric power capacity.
The single most important benefit from of using corn stalk is that it will not affect the food supply. And since corn is already being grown it will also not displace any other crop or disrupt natural habitats. Burning corn stalk does not require the development of any fundamentally new technology. Only some engineering work is necessary to ensure that corn stalk can be harvested, transported and burnt efficiently.
Corn stalk can be used for the greening of existing power stations with relatively small capital investment. The utilities are already using coal fired power generation for base load, i.e. always on power. A certain amount of base load power is critical for a reliable electric-grid. Blending agricultural residue with coal may be the simplest and fastest way to reduce net carbon dioxide emissions from existing coal fired plants. Some studies have shown that up to a 5% biomass blend with coal can be handled by existing power plants. Higher biomass blends will require some engineering development work. Xcel is already operating a small mixed fuel plant in Ashland Wisconsin. The flex fuel strategy is worth pursuing because there is enough available corn stalk to replace 40% of the coal used in Minnesota.
What should Minnesota do?
Corn stalk is a strategic biomass resource for Minnesota. Other excellent biomass resources that are currently being used for electricity like turkey litter or forestry residue are simply too small to make a statewide impact. Other resources like softwood timber are available but cannot be harvested in large enough quantities without environmental impact. Large scale planting of specialized crops for energy like switch grass or fast growing trees may displace food crops or disrupt the environment. Corn stalk is available now without any significant downside. We just have to figure out how to use it.
The two specific engineering challenges preventing the widespread use of corn stalk for electricity are efficient harvesting and efficient burning. Both of these challenges can be dealt by modifying existing technology that is much cheaper than developing fundamentally new technology. The harvesting process may require the modification of farm equipment design. Once harvested, the corn stalk must either be prepared to burn in coal fired plants or coal fired plants need to be modified to accept corn stalk. The market can solve both these challenges if the state catalyses the effort with incentives and mandates.
In the past the state of Minnesota had had used the legislation’s authority over the public utilities to drive renewable energy development. For wind power it culminated in the 2007 comprehensive energy bill but it started much earlier. Minnesota needs to act in 3 steps.
1. Use the public private partnerships to refine the technology. Many companies are already working on some aspects of the technology e.g. there is one company working on converting biomass into woody briquettes that burn like coal.
2. Once the technology has been demonstrated, the state should be able to use small focused bills similar to the 2007 C-BED bill to push for pilot project in different communities.
3. After the technology is proven, the legislation can require that the major utilities to adopt it. Coal prices are expected to be affected by global warming regulations and in a few years corn stalk could easily represent a $2 to $3 billion income stream that is diverted back to Minnesota farmers rather than being spent on coal.
Minnesota has a great opportunity to become a leader in biomass based electricity. Both major party presidential candidates are talking about controlling global warming. The US Supreme Court has already given the EPA some authority to regulate carbon dioxide. Minnesota needs to have a diversified portfolio of renewable technologies. The time to act is now. Engineering developmental projects take several years to complete. Amid growing concerns of global warming, agricultural waste like corn stalk is too important to waste.
Salman Mitha is an entrepreneur, businessman and scientist with over 20 years of experience in technology business and applied research. He has conducted research at Harvard University, run business operations in Silicon Valley and launched a startup in Minnesota. Salman earned his B.S. in Physics from the California Institute of Technology (Caltech) and his Ph.D. in Applied Physics from Harvard University. He lives with his wife and three children in Eagan.