Bioenergy Benefits and Barriers

Cost-Competitiveness

Bioenergy's cost-competitiveness is evidenced by its current role in the U.S. and state electricity supply portfolios: bioenergy facilities accounted for almost 59 billion kWh in 2002, which is equivalent to 1.6% of total U.S. power generation. Most of this electricity is produced by industrial cogeneration systems operating on wood or wood wastes. Municipal solid waste powered plants represent the second largest source of electricity, as well as the predominant source of power distributed over the grid.

A landfill like this can be the source for landfill gas, which is often a cost-competitive, environmentally-friendly way of obtaining energy from food, wood, or other organic waste that can not be or is not recycled.

In Massachusetts, the SEMASS Resource Recovery Facility in Rochester has a nominal capacity of 84 MW, and it handles 3,000 tons of solid waste per day from more than 20 communities. Several smaller waste-to-energy facilities provide an alternative to landfilling in other regions, while more than half of total LFG production in the state is already being converted into electricity. The U.S. Environmental Protection Agency estimates that only a few additional sites in Massachusetts have sufficient LFG resources to justify new installations.

Bioenergy's cost-competitiveness varies greatly depending on the fuel used, the proximity of the fuel source to the generating facility, and other site-specific factors. Residue and waste fuels may have little or negative marginal costs. By contrast, dedicated energy crops such as fast-growing trees and plants must be cultivated, harvested, transported, and processed, all of which contribute to fuel costs.

Because biomass have a low energy density compared to other fuels, transportation costs need to be minimized – most current grid-connected projects are sited based solely on resource availability. Highly efficient energy conversion technologies, such as biogasification, provide a means for improving the economics of power generation from low-energy-content fuels.

Scale and Availability

Bioenergy technology works at multiple scales. Grid-connected applications commonly include large wood and trash fired facilities as well as moderate and small units operating on landfill gas and other fuels.

At a much smaller scale, biodiesel cogeneration is emerging as a viable residential and commercial building technology in Massachusetts. The Allston-Brighton CDC in Boston is expected to be the first project to install such a system, and several other projects in the Boston area are studying this technology. Biodiesel cogeneration is an extremely cost-effective form of clean energy, combining the practical efficiencies of cogeneration technologies like diesel generators with renewable biomass fuels.

An additional benefit of bioenergy is its availability. Most bioenergy technologies can operate continuously, which differentiates it from intermittent renewables such as solar and wind energy. This has important cost and reliability advantages.

Security

Tapping bioenergy sources for power generation reduces dependence on fuels – including oil, coal, and natural gas – that must be imported to Massachusetts. Developing domestic bioenergy resources reduces U.S. reliance on foreign sources of fuel.

Air Emissions

Bioenergy's environmental and public health benefits can be influenced by fuel sources and energy conversion technologies.

All biofuels can replace or substitute for dirtier fuel sources. Most biofuels contain very little sulfur and no toxic chemicals, reducing emissions of sulfur dioxide and air toxics. Use of emissions control technologies at MSW-fired facilities is required to control release of potentially toxic materials that may be present in trash.

Bioenergy represents a "greenhouse neutral" option for generating electricity because biofuels are derived from organic materials. Using them simply accelerates the carbon cycle: carbon dioxide is released to the atmosphere – but only in an amount equal to or less than the amount that once-living organisms had originally absorbed from their environment.

Harnessing fuels such as landfill gas and digester gas not only displaces the use of more carbon-intensive sources, but also it can reduce the potential for global warming. If released to the atmosphere, these methane-rich fuels have a higher global warming potential than carbon dioxide. When these fuels are converted into energy, methane emissions are prevented. Because these fuels may have an unpleasant smell, using them may also help address odor problems associated with landfills, wastewater treatment plants, and livestock operations.

Rapeseed is a feedstock that is also used as a biofuel.

Resource Use

Bioenergy is considered to be renewable because useful energy can be produced in a manner that does not deplete finite resources over human timescales. Proper forestry practices must be maintained to ensure that wood-based fuels represent a sustainable resource. Growing dedicated energy crops also represents a sustainable option, so long as agricultural methods are sound.

Public Perception

Bioenergy is more likely than other renewables to be negatively perceived by the public and by government decision-makers. Contributing factors include its reliance on forest resources and waste materials – the former fuel source is often deemed to be something worth protecting, while the latter is viewed less positively than the sun, the wind, and the water.

Concerns exist about greenhouse gas emissions for wood-based fuels – net emissions are zero only if proper forestry practices are maintained – and about air toxic emissions for MSW-based fuels. Emissions of other air pollutants also raise questions, but bioenergy is unquestionably cleaner than some of the fuels used to produce electricity.

Even a shift toward dedicated feedstocks may require environmental tradeoffs, as extensive land areas may be required. Agricultural advances and biorefineries represent promising approaches for reducing the land intensity of energy crops and improving their economics.

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