Wood chips are part of the biomass family. And unlike other biomass materials such as agricultural crops, using wood will not lead to food shortages. Wood is also advantageous from the standpoint that it can be mixed with certain types of coal before the new compound is combusted. It can all be accomplished, say experts, without having to change the fuel-firing system.

"We look at the application of biomass co-fired with coal as the low hanging fruit that can be done commercially right now," says Ed Hennessey, chief executive of CleanTech. "Coal prices have increased dramatically in recent years and that has increased the value of the energy content in our biomass."

About 20 utilities in North America are now using wood chips to replace 5-25 percent of the needed coal or natural gas. State laws that have been enacted to require utilities to offer some green power are the impetus for the changes. In the case of Austin, its biomass plant would be part of the overall effort the city takes to achieve its goal of producing 30 percent of its power from green energy by 2020.

Among non-hydro renewable sources, biomass plays a key role today with 7,000 MW of installed capacity and producing 37 billion kilowatt hours of electricity each year, says the U.S. Department of Energy's Energy Information Administration. The Energy Department also says that the co-firing of biomass and fossil-fired fuels is the most immediate step that utilities can take to cut their carbon dioxide (CO2) emissions.

Biomass crops, such as trees, absorb CO2. When burned, however, the biomass material releases the CO2 back into the atmosphere. But such discharges are considered "neutral," meaning that the plants absorbed the same amount as the materials released -- unlike traditional fossil fuels that essentially discharge all new CO2 into the air.

Building a biomass plant from scratch is a hugely expensive undertaking. Estimates are that it costs twice as much as a coal plant. But co-firing the two together is working now in several states and also in Europe that has signed the global warming pact, the Kyoto Protocol. Sweden, for example, gets 19 percent of energy from bark, straw and wood chips and expects to receive 40 percent from such sources by 2020.

In this country, Pennsylvania is looking closely at the idea. "With 17 million acres of forests, Pennsylvania has generated significant interest from policymakers, energy analysts, industry representatives and others who are looking for new sources of energy," says natural resources secretary Michael DiBerardinis. He notes that no definitive decisions have been made yet.

Other Ramifications

If Pennsylvania decides to harness the resource, it says that it will first consider the ecological and social ramifications. Harvesting wood-based biomass for energy production, for example, would compete with the state's forest products' industry. It also says that current estimates of available low-grade wood that would be allocated to energy use are "overly optimistic" while it adds that the overall cost of conversion is not well understood by emerging industries.

By some estimates, it generally takes twice as much biomass to create the same amount of energy as coal. So, one kilogram of coal produces one unit of energy. To replace that, 2 kilograms of biomass would be required. At the same time, any industrial operation utilizing the technology needs to assure it would have a continuous supply of the underlying feedstock while also making certain that the biomass and the coal are compatible before they would be mixed and burned.

Mining coal and harvesting biomass are both involved processes. In the final analysis, however, advocates of biomass say that its benefits are appealing. While anthracite coal has more BTUs than bio-fuels, it also contains large quantities of sulfur, nitrogen oxide, particulate matter, mercury and CO2. With ever-stricter environmental laws and in a carbon constrained world, the value of facilities that use biomass will rise.

That's been the experience of the Public Service Co. of New Hampshire. Utilities in its neck of the woods are flocking to its door to buy biomass-derived power from it. The company took three well-functioning coal-fired boilers that were profiting and then converted those facilities into ones that could also burn wood chips. The change cost $75 million. But the new 50-megawatt facility actually has lower operational costs and higher earnings. Moreover, the utility's overall emissions have been drastically reduced.

The changes were made because New Hampshire implemented a renewable portfolio standard requiring its own utilities to supply a quarter of its energy from sustainable sources by 2025. Meanwhile, neighboring utilities are also required to offer their customers green options. For now, it's a seller's market in the New England region. That could change if an increasing number of utilities begin offering biomass alternatives.

"Large power plants need a viable carbon-reducing solution that can be quickly implemented without disrupting day-to-day plant operations," says Janusz Kozinski, dean of the College of Engineering at University of Saskatchewan. By replacing a portion of coal with wood chips and then co-firing the two together, utilities can immediately reduce their carbon footprints, the scholar says.

Using wood waste to produce energy won't lead to food shortages. But it might cause some fallout in other industries. Overall, though, the pursuit holds tremendous potential and allows the power industry to take immediate steps to reduce its carbon emissions.

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