What’s Next for Boardman?
Posted on May 24, 2011 by Yochanan Zakai
Tags, Climate and Conservation, Emerging Technologies, Generation, Transmission, Distribution
The Citizens’ Utility Board (CUB) has been actively involved in the unprecedented process that will end the burning of coal at Portland General Electric’s (PGE) Boardman power plant. On this blog we described how the most effective arguments in support of closing the plant were economic, not environmental. In December 2010 we reported on the long journey that resulted in the first agreement to close a modern coal plant before the end of its intended life. Today, as a part of our ongoing series exploring emerging renewable energy sources, we are looking at the options for repowering the Boardman plant.
PGE plans to discontinue burning coal at Boardman by the end of 2020. What will happen to the Boardman plant when that occurs? Although no plans are final until approved by the Public Utility Commission, there is a process underway which will determine whether it would be feasible to retrofit the plant and to burn torrefied giant cane grass in a plant originally built to burn coal.
Giant cane grass looks similar to bamboo (see photo). Today it is used as an ornamental plant and as a reed in woodwind instruments. Giant cane grass can be grown in marginal soils with low nitrogen content, is harvested twice a season, and is high in energy content. Tests conducted by Washington State University near Boardman show that each acre of irrigated land can produce 25-30 dry tons of cane grass. Additionally, giant cane grows up to 30 feet tall and no pesticides are necessary to grow the crop in Oregon.
PGE estimates that 60,000 to 90,000 acres of giant cane would need to be planted to supply the retrofitted plant’s needs. Today approximately 220,000 acres of irrigated cropland is located within 50 miles of Boardman; keeping production close will reduce the cost and carbon emissions from the transportation and aggregation of cane grass.
A common critique of biomass production is that energy crops will displace food crops and therefore increase the cost of food. PGE plans to pay giant cane farmers an amount comparable to the cost of crops that are used for animal feed. PGE contends this will prevent displacing high-value food crops, such as potatoes, that are grown in the area. CUB is sensitive to this issue and will further examine land availability and PGE’s plans before supporting any final proposal.
Another potential concern about giant cane grass is its ability to spread beyond the fields in which it is planted. In California, giant cane is considered an invasive species, but in Oregon’s climate the crop cannot produce its own seeds. As a result, the only way for giant cane to reproduce is if part of its root structure is torn out of the ground and comes to rest in a new location. This has been observed in areas where flooding or turbulent streams frequently modify the landscape. The Oregon Department of Agriculture rates giant cane a risk category B weed. Current plans call for the spread of giant cane to be managed by: (1) planting only outside of riparian areas and the 100 year floodplain, (2) not planting near running water, and (3) controlling transportation practices. This plan also calls for any unexpected spread of giant cane to be controlled by a denial of water or the application of common herbicides.
A further concern about the introduction of an irrigation-dependent crop is its potential to deplete the aquifer in the area. PGE responds that giant cane grass uses the same amount of water, about 30 inches per acre, as the alfalfa it is expected to replace. CUB recognizes that this issue also needs further study, as does the question of whether there are any significant risks of relying on a monoculture to grow an alternative fuel source.
Giant cane grass must be torrefied in order to be used at Boardman. Torrefaction is a cutting-edge technology that heats the crop in a low oxygen environment. After heating the giant cane (imagine bamboo in a giant coffee roaster), a charcoal-like substance that has an energy content of 10,000 BTUs (British thermal units) per pound is produced. This torrefied cane has higher energy content than the coal used in the plant today. Torrefied cane is also low in sulfur and mercury, so it will burn cleaner and more efficiently than coal.
While the process of harvesting, torrefaction, transportation, and burning of giant cane may emit less carbon than burning coal, a greenhouse gas life cycle analysis needs to be conducted by a respected scientist. Even the Environmental Protection Agency (EPA) is unsure how to quantify emissions from biomass facilities. In January 2011, EPA delayed (for several years) making a decision on how to regulate carbon dioxide emissions from biomass facilities while seeking “further independent scientific analysis of this complex issue.” A full analysis of this proposal’s environmental impact will include an accounting of greenhouse gas emissions.
In addition, while burning torrefied cane results in fewer sulfur and mercury emissions than coal, a repowered Boardman plant may require additional pollution controls. The economic analysis of Boardman as a coal plant demonstrated that it would cost about $200 million less to close the plant and avoid pollution control investments. Pollution control costs may also influence whether Boardman is cost effective as a biofuel plant.
Under its pilot program PGE is contracting with local farmers to grow giant cane on approximately 100 acres. The company plans to conduct a 24 hour test in 2013 during which only torrefied biomass will fuel the Boardman plant.
PGE hopes that this test fire, along with other research, will provide information permitting it to keep Boardman open, with minimal retrofitting, past 2020. PGE also hopes that such a step would preserve the 100-plus jobs at the plant and create 60 new jobs at three torrefaction facilities in the area. PGE will examine the results of the test batch before proposing to continue operating the power plant on giant cane grass. Constructing torrefaction facilities will cost between $350 and $450 million, and CUB isn’t ready to support such a large investment until more information on the cost and benefits of this proposal are available. If PGE submits a long-term proposal to use torrefied giant cane at Boardman, CUB will carefully examine the proposal’s impact on food production, carbon emissions, water use, other environmental risks and concerns, and utility rates.
In the mean time, we’re looking forward to seeing the results of the test fire. We will also keep an eye on other emerging renewable energy technologies that are proposed for use in Oregon.
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03/23/17 | 1 Comment | What’s Next for Boardman?