A 50MW boiler fueled by burning wood chips at the Schiller Station in Portsmouth has replaced a similarly sized coal boiler. The $70m Northern Wood Power Project for Public Service of New Hampshire (PSNH) will burn more than 400,000t of wood annually, most of which is being sourced locally.
Brought on line in December 2006, Schiller Station is one of the state’s largest renewable energy projects. The plant will generate above 300,000 RECs (Renewable Energy Certificates) each year, with income from selling the RECs to regional energy suppliers offsetting the project’s capital costs.
WOODCHIPS REPLACE COAL BURNING
Previously, PSNH’s Schiller Station in Portsmouth ran three 50MW coal-fired steam boilers that were built in the 1950s. PSNH has now replaced one of these coal boilers with a new fluidised-bed boiler burning whole-tree wood chips and other clean low-grade wood materials.
The project was one of the largest renewable energy projects in the US, and one of the first to replace fossil fuel generation with an equivalent amount of cleaner electric power. Every year, PSNH used to buy about 400,000t of low-sulphur coal to fuel Schiller Station’s three boilers.
The wood fired plant will power around 50,000 New Hampshire homes while reducing coal use by over one third, or 130,000t annually. That will reduce emissions by thousands of tons annually, helping to meet the requirements of the New Hampshire Clean Power Act.
FLUIDISED-BED BOILER CIRCULATES WOOD CHIPS
Primary components include a wood-fuel delivery system, a large covered wood storage facility that holds about 10,000t of wood chips, a covered conveyor to deliver chips to the 110ft-high boiler, and emissions control systems.
Unlike typical ‘stoker grate’ boilers, where wood chips are simply burned as they pass along a rolling grate, the fluidised-bed boiler circulates the wood chips and burns them while they are suspended in air within the combustion chamber.
This process burns fuel more completely, dramatically reduces the production of nitrogen oxides and other emissions, and captures any unburned carbon compounds for further combustion. The new boiler system more efficiently converts water to superheated,
high-pressure steam, which spins the turbines to generate electricity.
STRONG LOCAL BACKING
In August 2003, PSNH filed a plan for approval by state regulators to develop The Northern Wood Power Project. Construction began in October 2004, following a review by state regulators and by planning boards.
The RECs generated by the project can be sold or traded to electric suppliers and utilities that do not have sufficient renewable energy resources of their own. RECs are in high demand in an emerging energy market.
States in the US like Massachusetts and Connecticut have mandated that their electric suppliers add renewable energy – commonly known as ‘green power’ – to their energy portfolios.
The Northern Wood plan gained widespread local support, including advocates from many New Hampshire organisations. Supporters of the project include the Audubon Society of New Hampshire, the Society for the Protection of New Hampshire Forests, the New Hampshire Timberland Owner’s Association, the Governor’s Office of Energy, the NH Department of Resources and Economic Development, the Seacoast Science Center, the NH Business and Industry Association, and the Portsmouth Chamber of Commerce.
THE STATE’S LARGEST ELECTRIC UTILITY
PSNH is New Hampshire’s largest electric utility, generating and distributing electricity for more than 490,000 homes and businesses. Each year, PSNH supports dozens of forest protection, energy conservation, and environmental organisations through both financial contributions and generous employee voluntary work.
With three fossil fuel-fired plants and nine hydroelectric facilities, PSNH can generate more than 1,110MW of electricity. That meets about 70% of energy requirements. The utility runs a number of programmes to help residents and companies use energy more efficiently.