GAO Preliminary Observations on Links Between Water, Biofuels and Electricity; Calls for More Research
13 July 2009
The Government Accountability Office (GAO) last week provided preliminary observations as testimony to the House Subcommittee on Energy and Environment, Committee on Science and Technology on the water-energy nexus related to biofuels and water and thermoelectric power plants and water.
The subcommittee had requested GAO undertake three studies related to (1) biofuels and water, (2) thermoelectric power plants and water, and (3) oil shale and water.
In the testimony, GAO provided key themes that emerged from its work to date on the research and development and data needs with regard to the production of biofuels and electricity and their linkage with water. GAO said that its work on oil shale is in its preliminary stages and further information will be available on this aspect of the energy-water nexus later this year.
Water and energy are inexorably linked: energy is needed to pump, treat, and transport water and large quantities of water are needed to support the development of energy. However, both water and energy may face serious constraints as demand for these vital resources continues to rise, the GAO report said.
Two examples that demonstrate the link between water and energy are the cultivation and conversion of feedstocks, such as corn, switchgrass, and algae, into biofuels; and the production of electricity by thermoelectric power plants, which rely on large quantities of water for cooling during electricity generation.
While the effects of producing corn-based ethanol on water supply and water quality are fairly well understood, less is known about the effects of the next generation of biofuel feedstocks. Corn cultivation for ethanol production can require from 7 to 321 gallons of water per gallon of ethanol produced, depending on where it is grown and how much irrigation is needed. Corn is also a relatively resource-intensive crop, requiring higher rates of fertilizer and pesticides than many other crops.
In contrast, little is known about the effects of large-scale cultivation of next generation feedstocks, such as cellulosic crops. Since these feedstocks have not been grown commercially to date, there are little data on the cumulative water, nutrient, and pesticide needs of these crops and on the amount of these crops that could be harvested as a biofuel feedstock without compromising soil and water quality. Uncertainty also exists regarding the water supply impacts of converting cellulosic feedstocks into biofuels.
Water usage in the corn-based ethanol conversion process has been declining and is currently estimated at 3 gallons of water per gallon of ethanol, according to the GAO. However, the amount of water consumed in the conversion of cellulosic feedstocks is less defined and will depend on the process and on technological advancements that improve the efficiency with which water is used.
...Our work also indicates that even less is known about newer biofuels feedstocks such as algae. Algae have the added advantage of being able to use lower-quality water for cultivation, according to experts. However, the impact on water supply and water quality will ultimately depend on which cultivation methods are determined to be the most viable. Therefore, research is needed on how best to cultivate this feedstock in order to maximize its potential as a biofuel feedstock and limit its potential impacts on water resources.
The GAO said that other areas that relate to water and algae cultivation in need of additional research include:
Oil extraction. Additional research is needed on how to extract the oil from the algal cell in such a way as to preserve the water contained in the cell along with the oil, thereby allowing some of that water to be recycled back into the cultivation process.
Contaminants. Information is needed on how to manage the contaminants that are found in the algal cultivation water and how any resulting wastewater should be handled.
Finally, additional research is needed on the storage and distribution of biofuels, GAO said. For example, to overcome incompatibility issues between the ethanol and the current fueling and distribution infrastructure, research is needed on conversion technologies that can be used to produce renewable fuels capable of being used in the existing infrastructure.
...While we recognize that DOE currently has a number of ongoing research efforts to develop information and technologies that will address various aspects of the energy-water nexus, our work indicates that there are a number of areas to focus future research and development efforts. Investments in these areas will provide information to help ensure that we are balancing energy independence and security with effective management of our freshwater resources.
Resources
Agriculture is the biggest use of water in the US. Careful processes can recycle water for oil shale production if any is needed.
Large coal or natural gas or nuclear power plants do not need to evaporate water in the standard large cooling towers, but it is frequently less costly to buy the water and do so. Dry air cooled condensers are possible and are especially possible for nuclear power plants where the fuel costs are very low and the equipment costs are the major part of the cost of the produced electricity. Ocean water could be used to cool power plants and also the waste heat could produce much fresh water from ocean water.
No large power plants should burn natural gas as this can be used on customer sites for co-generation or combined heating-cooling-power units. Cogeneration is the most cost effective way of both reducing energy consumption and CO2 release. All government buildings that burn gas should be converted immediately to combined heating, cooling and electricity.
Capstone now has 200 KW turbines with high efficiency and low maintenance. Generators used, ordinarily, for Geothermal energy can also be used to produce additional electricity from the turbine exhaust if there is no other use for the heat. Such units are more cost effective and far more reliable than wind turbines. No water is needed for such systems.
For the US industry and transportation systems biofuels are a myth. Looking at the efficiency that plants convert sunlight and the efficiency of the conversion of this cellulose or starch into biofuels, there is not enough land area in the US to supply the energy needs. Only a few square miles are needed for the nuclear power plants required to replace all coal fueled power plants of the US. Part of the coal can then be used to make jet fuel, diesel and gasoline.
High voltage Direct current cables can be buried in the right of way of all the freeways and any other roads in order to move electricity from one side of the country or another. There are already commercial operations of such facilities including a much more complicated cable from Norway to Holland. A system has already been built which would allow inserting or extracting power at any point along such cables. Low cost sodium can be used for the conductors in such cables in most places. The conductors can be very large or there can be multiple ones, but they do not need a pipe greater than ten inches in diameter under bridges. The trenches needed are equally small. Iron or steel covers can protect the cables from accidental damage and they are not bothered by wind or ice.
The ZEBRA battery that GE is also going to make for locomotives and trucks can allow the electrification of many of the rail roads in a far cheaper form. No longer will there be a need for a continuous wire over a track. New electric light rail systems can also eliminate or not install many miles of such wires with associated poles and supports. The power supply systems for such wires can also be eliminated or simplified.
Nuclear reactors on or near ocean coasts are part of an answer to both water and energy issues. Several nuclear reactors in Southern California could eliminate the need for much if not all of the Colorado river water now being used and that of the Owens Valley as well for the cities. People who can afford to buy bottled water can afford the much lower prices for desalinated ocean water. The cost to desalinate it can be lower than a dollar per thousand gallons and perhaps much lower with cheap heat.
It is cheaper to make hydrogen with electricity at nuclear power plants than it is to use oil at 150. Gasoline from coal can compete with oil at 40. There must be an import tax of $35 on foreign oil to preserve the cost effectiveness of such units just as there is a tax of $50 or more on imported ethanol per barrel of oil equivalent energy. ..HG..
Posted by: Henry Gibson | 13 July 2009 at 03:03 PM
If you propose using sodium metal for conducors of electricity best be sure they are well sealed lest water causes an explosion. That's not going to be cheap.
In the case of a disaster this may be impossible.
Posted by: Mannstein | 13 July 2009 at 04:46 PM
HG:
I thought that ethanol import tax was $0.56/gal or about $19.32/barrel.
However, a much high import tax on crude oil would be justified. Your proposition for $35/barrel would be fair enough. At about 13 million barrels/day, that would give a $166 B/year revenue to fix roads and promote cleaner vehicles.
By the way, gasoline price would go up about $2/gal at the pump. Dont know how that would be accepted but it would not be unmangeable if applied progressively over a 3 or 4 years.
On the other hand, the import tax on ethanol (a cleaner fuel) should be progressively abolished.
Posted by: HarveyD | 14 July 2009 at 02:52 PM