As Maryland works toward its decarbonization goals, clean energy advocates – and some foresters – insist wood energy could become a significant clean source of thermal energy in the state and stoke the creation of more clean energy jobs.
“This is a really significant opportunity for Maryland. Wood energy could complement other clean energy sources very well,” said Anne Hairston-Strang, Ph.D., Associate Director of the Maryland Forest Service at the Department of Natural Resources (DNR).
“Not many people focus on decarbonizing thermal energy or know much about it. But a little more than one-third of all energy use in the country is for heating and cooling, and there are opportunities to meet some of that energy need with clean, wood systems,” said Dan Wilson, Vice President of Wilson Engineering Services.
Unlike vintage wood stoves that burned cord wood and emitted considerable smoke and particulates, modern wood energy systems meet both state and federal clean air standards. The fuel is wood residue, such as wood collected during urban/suburban tree trimming, leftover materials (bark, sawdust, etc.) from forest products industries and immature wood removed during forest management operations. Modern boiler and gasification systems can efficiently turn that fuel into heat, hot water and combined heat and power for commercial, industrial and institutional facilities.
In Maryland, that technology could serve a variety of clients – hospitals, schools, college campuses, and apartment complexes or office complexes with district heat systems. It could also serve a variety of industrial and agricultural facilities.
“Wood could provide process energy for the food processing companies, the greenhouse industry and potentially the poultry industry,” said Lew McCreery, Forest Products Technologist with the Forest Health and Economics Forest Service of the U.S. Department of Agriculture. “The University of West Virginia did some research that identified wood energy as a viable source of heat for brooder houses.”
The capital costs of installing a large wood energy system are considerably higher than the cost of mainstream, fossil fuel systems. Fuel and operational costs, however, are considerably lower, making wood energy systems economically attractive in certain circumstances.
Wilson – whose company specializes in helping clients find economically viable, clean thermal energy solutions – points to the example of the Holderness School in New Hampshire. The 25-building campus converted its district energy system from a fuel oil boiler that generated steam to a woodchip boiler that delivered hot water. The woodchip system which satisfies 95 percent of the campus’s heating needs and is backed up by a propane boiler, has saved the school $300,000 a year in heating costs and those savings have financed the system’s capital cost, Wilson said. The wood energy system has also cut greenhouse gas emissions from campus heating operations by 90 percent.
On average, the capital cost for a large wood energy system is two to three times more than a comparable fossil fuel system, Wilson said. However, raw wood residue which fuels the system, costs just 25 to 33 percent of propane or fuel oil, “so you can get some very nice projects that pay back within five to 10 years on a system that has a lifespan of 25 years and that’s before you consider any incentives.”
“Over the life of the building, the savings can be substantial when you compare the cost difference of natural gas per million BTUs and wood per million BTUs,” McCreery said. “The price per million BTUs for natural gas currently is about $10. Wood is about $4 to $5 per million BTUs.”
The price of natural gas, he added, is rising and projected to continue rising in the near term.
Other developments could also make wood energy viable for more Maryland sites. Technology advances in several European nations have cut particulate emissions from wood gasification systems by as much as 98 percent and boosted the efficiency of wood combustion systems to between 90 and 95 percent,” McCreery said. European innovators have also produced wood-powered hot water systems that work effectively at lower temperatures – typically 110 to 120 degrees Fahrenheit – “which creates a really efficient, low-maintenance, cost effective system.”
Greater adoption of wood energy could generate other benefits for Maryland, Hairston-Strang said. Because wood pellets and raw wood residue are too bulky to cost-effectively transport long distances, wood energy companies would have to be locally based. Most areas of Maryland – including urban centers with high levels of tree trimming – could be viable locations for new wood energy companies.
An expanded wood energy market would facilitate improved forest management in Maryland, she added. A market for cut wood which is not large enough to be used by forest products companies, would enable foresters to thin stands, remove excess ‘fuel’ that could contribute to forest fires and “provide more growing space, more water, more nutrients to remaining trees.”
A wood energy market could also ease current issues with wood waste and emissions, Wilson said. While some urban tree trimmings are turned into mulch, others are simply landfilled. Some wood residue from forest trimming or forest products industries is burned or piled in heaps to decay – practices that generate greenhouse gases. Expanded wood energy operations could put those discarded materials to beneficial and clean use.