Growing Fuel: Biomass Plantations


Biomass generation plants primarily burn waste wood, but as their role in clean energy is expanding, more wood will be needed. Where will it come from?

Xcel energy has developed a demonstration project to test which tree species, soils and climates will be most conducive to “biomass plantations” – trees grown to be used as fuel. In partnership with the Wisconsin Department of Natural Resources and the University of Wisconsin Cooperative Extension, the project includes two newly planted, 10-acre test plots. Each has been planted with a variety of trees, including poplar, larch, aspen, willow and red pine – all genetically crossed to be fast-growing.

When used as a power generation fuel, trees are considered carbon-neutral because they absorb carbon while they grow; then they release what they absorbed when they become biomass fuel.

Agroforestry: New revenue opportunities for farmers

The partners in the pilot are tracking the development costs (ground preparation, weed control, etc.) because they’ll provide budget estimates to farmers who are interested in creating their own plantations. Many farmers in the area are not using their low-yield land, and the trees would provide incremental revenue.

Most of the trees in the pilot will be harvested in about 10 to 15 years when they reach six to eight inches in diameter. Willows, which grow more like shrubs, could be ready in as little as three years.

Until the trees are large enough to form a canopy, the pilot partners are planting grains in the rows between the trees, providing yet another source of income.

This is not your uncle’s ethanol

When ethanol was hailed as a replacement for gasoline, farmers around the world switched their crops to corn to capitalize on the ethanol boom. The unintended consequences became apparent when rice, beans and other nutritional staples were in short supply.

The biomass plantation test plots are located on vacant, “marginal” agriculture land that’s not conducive to growing high-yield food crops.

Another aspect of the test is to see how well the trees grow without irrigation. The plots are located in different climates and planted in different soil types, which will add more helpful data points to the test.

All of the wood from the plots will be chipped and delivered as fuel for Xcel Energy’s Bay Front plant.

The table below shows the power Xcel Energy purchases from generation plants that use waste as fuel. Xcel Energy also owns four others that use waste wood or refuse-derived fuel: Bay Front, French Island, Red Wing and Wilmarth.

My personal favorites are the landfill gas-to-energy and the poultry waste (a.k.a. turkey “litter”).

Article by Sheila Knudtsen, appearing courtesy Xcel Energy Blog.

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