Topic Area: Energy
Geographic Area: Kettle Falls, Washington
Focal Question: Is Biopower a sustainable and cost-effective energy choice?
(1) Profiles in Renewable Energy: Case Studies of Successful Utility-Sector Projects. <http://www.nrel.gov/documents/profiles.html> March 19, 2002.
(2) “Biopower: renewable electricity from plant material.” Energy Efficiency and Renewable Energy Network (EREN) Website. <http://www.eren.doe.gov/biopower/basics/index.htm> March 19, 2002.
(3) “Washington Bioenergy Resources.” Energy Efficiency and Renewable Energy Network (EREN) Website. http://www.eren.doe.gov/state_energy/tech_biomass.cfm?state=WA March 19, 2002.
Reviewer: Aaron K. Bond, Colby College ‘02
The principal current sources of energy are fossil fuels, which are finite and nonrenewable. Producing energy with fossil fuels as the main input also places a great deal of stress on the environment. In response to these issues, much time and research has been devoted to developing alternative energy sources. One such alternative is Biopower. Biopower is the use of plant matter such as trees, grasses, agricultural crops, or other biological materials to produce electricity or heat. This plant matter, referred to as biomass, is a renewable energy source that is an alternative to fossil fuels. Today, biomass is used primarily for the generation of electricity by means of a steam cycle (2). First, biomass material is converted to steam in a boiler, and then the steam turns a turbine that is connected to a generator, which produces electricity. Biomass can also be used with coal to produce power in an existing power plant, cutting costs and reducing pollution. Another use of Biomass entails converting it into fuel gas, which can then be used in a piston-driven engine, high-efficiency gas turbine generator, or a fuel cell (2).
The Kettle Falls Wood-Fired Plant in Kettle Falls, Washington is one example of the application of biopower. During the late 1970s, the Washington Water Power Company (WWP), looking to expand its electricity supply base, began researching alternative energy sources (1). The WWP, an investor-owned utility serving customers in eastern Washington and northern Idaho, needed to increase its supply base to keep up with the increasing demand in the area (1). Recognizing that an abundance of wood waste was being created by the large local timber industry, the WWP developed a plan to build a new power plant that would use biomass as its only input.
A biopower plant was expected to benefit the WWP, the timber industry, and the environment. The WWP was looking for a cost-effective way to expand its electricity supply capacity. The abundance of wood waste in the area meant a relatively inexpensive fuel was not being utilized. At the same time, the primary method of disposal of the wood waste, or residues, was to burn it in wigwam burners. The wigwam burners had no pollution controls and thus air pollution was a major concern. Building a new power plant that ran entirely on the residues purchased from the local timber industry could help reduce this source of pollution. In turn, the timber industry would benefit by turning disposal costs into revenues. And the WWP would have an inexpensive fuel source to operate the new plant.
The Morrison-Knudsen Company undertook the task of designing and constructing the 42.5-MW steam-generating plant in Kettle Falls (1). Kettle Falls was chosen as the site for the new plant due to its proximity to the lumber mills that would be providing the biomass for the plant. The plant began commercial operation in December 1983. The total capital cost of the plant was about $85.9 million, or slightly more than $2,000/kW (1). In comparison to a conventional fossil fuel plant of roughly the same size, the initial costs associated with the biopower plant were high (1). However, the WWP found that these costs would be recovered over time due to low fuel and operating costs. To keep fuel costs low, the WWP maintains long-term waste delivery contracts (5- to 10-year) with about 15 large lumber companies within a 100-mile radius of the plant (1). The WWP also signs short-term contracts to take advantage of competitive markets for the wood waste. In 1989 the cost of fuel was 1.22 cents/kW and total operating cots were 1.43 cents/kW, for a total plant generating cost of 4.65 cents/kW (1).
The Kettle Falls plant has been an operating success as well. The plant's availability factor has averaged about 95%, and it has also consistently operated at a power output of 47 MW, which is 4.5 MW greater than its nameplate rating (1). A plant service factor of 75% was expected, but it has been as high as 95% (1). However, costs are still high enough that the biopower plant is usually shut down during the spring runoff, when inexpensive hydropower is readily available.
The plant is also considered a success in terms of environmental concerns. Not only did the plant eliminate the need for wood waste to be incinerated in wigwam burners, but it was also designed, and operates, with environmental concerns in mind. The plant's boiler produces ash, which goes through a complex particulate removal system. The ash recovered from the system is then disposed of in a dedicated solid-waste landfill or marketed as a liming agent, which, when added to soil, decreases acidity (1). The ash that is not recovered is released at an emission rate of 0.003 grains per standard cubic foot (gr/scf), which is well below the state threshold of 0.02 gr/scf (1).
The Kettle Falls Wood-Fired Plant proves that biopower can be cost-effective and more sustainable, through its use of renewable resources, than fossil fuel plants. The Kettle Falls plant has succeeded to date for several reasons. First, the elimination of the environmental problems associated with the wigwam burners garnered a great deal of initial support for the project. The plant also gained support due to the use of local fuel and labor. And finally, the plant has been able to overcome high initial costs through above-average plant performance and low cost fuel (1). On the downside, the WWP is in the precarious position of complete dependence on the fuel supply within the 100-mile radius of the plant. Beyond the radius, the fuel costs are prohibitive (1). As a result, if the timber industry reduces output and supply of wood waste decreases in the future, fuel costs will increase and the plant’s service factor will decrease. In this case the plant would not be economically viable. The scenario described, however, has not materialized to date.
Biopower, in general, is gaining support worldwide due to its environmental, economic, and national security benefits. Biomass use can improve environmental quality by offsetting fossil fuel use and related emissions, and by using wastes that are creating land use problems (2). Economic growth is also stimulated in many areas by the creation of new markets for biomass. It can also be a positive in terms of national security, as it reduces the dependence on foreign fossil fuels. Biopower appears to be a viable alternative to fossil fuels, with potential to be a modest contributor to world energy needs.