Small coal-fired plants are particularly vulnerable to economic and environmental pressures, putting some plant owners in what seems like a no-win position. But an emerging option—biocoal from...
Biomass Fuel Foibles
Fuel-supply risks stunt the growth of biomass power.
project, it’s absolutely essential to work with a fuel-sourcing expert who can go through the whole process.”
Because contracts can and do fall through, ensuring a consistent supply requires contracting with 10 or 20 different providers, from small mulching operations all the way to large forest-products plants. Plant operators must study fuel-supply issues at the micro level. “It’s on-the-ground work, actually talking to your neighbors who have waste streams,” Crossman says.
The most successful biomass-generation strategies rely on a variety of feedstocks. Conversely, the riskiest projects are built to use a single fuel source. A plant that burns wood shavings, for example, could end up at a loss when markets change and suppliers fetch higher prices in the animal-bedding market. “You often lose your best fuel sources because they have a higher use,” Carlson says.
In some cases, plant operators address fuel risks by processing, or even growing their own fuel. “The further upstream you can go in the fuel sourcing the better,” Carlson says. While the economics of this may not make sense at this point—waste fuels remain cheaper than cultivating and harvesting biomass—dedicated fuel crops might become a more attractive option as demand rises for waste fuels and growers gain experience with such crops as fast-growing trees and grasses.
Unfortunately, even the best plans can fail if another facility is built between a plant and its source of fuel. This exact situation already has happened in California, according to Bodington, and is now happening in the Northeast. In these cases, facility operators must try to find new sources of feedstock, and often will refurbish or retrofit plants to increase the diversity of fuels they can burn. Such situations likely will increase as the market grows.
Creating a Bioenergy Campus
Project developers find some of the best opportunities in co-firing biomass with coal at existing coal-fired plants (see sidebar, “Co-Firing: Low-Hanging Green Fuel”), or converting formerly coal-fired plants to burn biomass exclusively. “That’s another niche that’s never been exploited but should be,” Carlson says. In many urban settings, for example, small, defunct coal-fired boilers might be refurbished to use urban sources of biomass fuel. “Those two line up very well,” Carlson says. For example, Northeast Utilities recently repowered a coal-fired plant in Portsmouth, N.H., to burn biomass.
Cogeneration also provides opportunities for biomass development. Cogeneration plants offer a major efficiency advantage, delivering 60 percent to 80 percent efficiency rates versus the typical 25 percent to 27 percent for a large, decentralized plant. Additionally, they can benefit from an income stream for highly valued steam and all the synergies of locating at an existing industrial site, removing many permitting and transmission issues.
“In an ideal situation, any kind of convergence of siting a plant like this near a fuel source and a thermal load—that is the perfect configuration,” says EPA’s Crossman. “Once you start putting all those pieces together, the projects become so attractive they stop you in your tracks.”
Finding these opportunities for cogeneration can prove challenging, however. Identifying and implementing a more integrated “bio-energy campus” of public and private interests