|By Dave O’Connor, Biomass Program Manager, EPRI|
To a casual observer, it might appear that biomass power has become dormant in the U.S. To some degree, that analysis is correct, but the picture is complex. Utilities and independent power producers once had plans to install significant amounts of biopower—FirstEnergy was converting two units at its Burger coal plant to biomass; Georgia Power was studying ways to convert its 165-MW Plant Mitchell to 100-MW of biopower, and a joint venture between Areva and Duke Power announced plans to build up to ten 50-MW biomass plants in the U.S. For different reasons, these plans and others have slowly abated. Confounding the situation are uncertain regulations regarding carbon emissions and biomass carbon accounting. On the other hand, biopower is growing at a rapid rate in Canada, where Ontario Power Generation is converting two stations to biomass, and Europe-based RWE has invested heavily in U.S. wood pellet production.
So does biopower have a future in the U.S., or will it be relegated to a marginal role? Unfortunately, the vision of the future of domestic biopower remains unclear, crowded out by the forest, so to speak. But there are conditions and technologies that will let biopower grow.
It’s worth noting that biopower is currently growing in the U.S.—the Energy Information Administration notes that 549-MW was added in 2013, and quarterly reports indicate continued growth. The growth is largely from smaller units that might be considered a distributed power source. EPRI, the U.S. Department of Energy and many others are designing the grid of the future, and distributed power resources – possibly coupled with hot water/steam production – are one of many driving factors forcing this substantial undertaking. Small, distributed biopower offers two significant technology advantages: first, biopower is a dispatchable renewable source; second, small biopower relies on local supply. Smart plant siting that matches grid issues with proximity to biomass supply offers support for electric distribution issues and cost control through minimized fuel transportation.
The most obvious condition in deploying domestic biopower is the status of sustainably harvested biomass in a carbon accounting system. EPRI work shows that while somewhat variable, the life cycle greenhouse gas emissions of biopower typically range from 20 to 50 gCO2e/kWh, comparable to other renewable generating options. The lifecycle analysis captures the impact of, say, diesel fuel used in transportation and equipment operation, fertilizer if applicable, processing, etc. This approach considers the biomass carbon “biogenic”, which is consistent with previous U.S. Environmental Protection Agency (EPA) regulations. However, if a “carbon is carbon” approach is used, which discounts the biogenic aspects of the feedstock carbon, the emissions rise by nearly 40 times. EPA is expected to offer accounting rules by year-end, but uncertainty has helped cool interest in biopower.
A suite of generation technologies is ready for adoption, including direct combustion, co-firing, unit conversions and biomass upgrading. EPRI has worked with electric utilities to understand the implications of each option, and have prepared numerous reports and papers, and conducted tests of each option. For example, EPRI recently collaborated with Southern Co. and others to test an upgraded biomass (torrefied wood) at Gulf Power’s Plant Scholz that found the torrefied wood was a very good co-firing fuel from a technical perspective. Economics were not addressed in the project.
The economics of biomass power generally depend on two familiar aspects: capital cost and operating cost. Many technologies offer low, attractive capital costs, including firing certain upgraded fuels, many types of co-firing, and unit conversion. Probably the largest impediment to broad biopower deployment is the operating cost, which is mostly the cost of the biomass. Biomass costs vary significantly, depending on local supply conditions, but also transportation requirements, local regulations, etc. Offsetting the cost of the biomass with renewable energy or carbon credits has proven to be an effective strategy in many domestic and international jurisdictions. These credits have the effect of reducing the overall plant variable cost, which allows the plant to effectively bid into the electric system at a discounted rate. While not completely necessary (especially with 549-MW of biomass added last year), financial recognition for the carbon value of biopower would increase the installed domestic base, just as it has in Europe.
In summary, biomass power is commercially-available and ready to be domestically deployed. Regulatory uncertainty and feedstock cost are the likely reasons that the roll-out has been slow. Small distributed biomass power stations may have additional value due to their dispatchability and access to discrete, low cost biomass supply.
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