Article #225, August 2015
By Bill Cook
Wood energy, done with known, efficient, and affordable technologies, is one of the most environmentally-friendly energy sources at our disposal. Not only is it renewable and sustainable, but it’s locally-sourced and most easily contributes to the heating and cooling sector.
Renewable energy choices are best made when playing to the strengths of different regions. Michigan has an abundance of wood where inventories increase every year. A portion of that annual volume could be diverted to renewable energy production.
Another aspect of playing to the strengths of different regions is matching the most suitable feedstocks to the form in which energy is consumed. For much of Michigan, especially northern Michigan, using wood for heating and cooling is a sensible and easily deployable technology.
For the smallest spaces, such as homes and small businesses, using high-efficiency, low-emissions backyard boilers is usually the least expensive option. These boilers can be competitive with natural gas, but the cost savings can be quite significant when propane, fuel oil, or electric heating is replaced with wood.
These high-efficiency outdoor boilers have higher purchase costs, but the payback in lower fuel use is often under five years. So, considering the life of the boiler, the more expensive units are actually cheaper in the long run, and better for the environment, too.
One of the downsides of these outdoor firewood boilers is that they need their fireboxes loaded daily, and the work involved with making firewood isn’t for everybody.
Pellet furnaces, boilers, and stoves are alternatives to the more labor-intensive firewood technologies. Pellets are more expensive than firewood, as they are more value-added feedstocks, but the systems have considerably less maintenance, depending upon the size of their auto-feeding hoppers. Bulk delivery of wood pellets is nearly as labor-free as conventional propane or fuel oil units. Michigan has over 300,000 households that burn propane. Conversion to wood pellets can save on heating costs and provide environmental benefits.
For larger buildings, or groups of buildings, a wood-chip boiler is typically a low-cost, environmentally-friendly technology. There are numerous examples of this deployed technology across the Lake States. Wood chips can be used for space heating, the production of hot water, and air conditioning (through absorption chillers, like those in RVs). When multiple buildings are connected to a central boiler, the term is a district energy system.
These wood chip and district energy systems can be cost competitive with natural gas and usually undercut heating and cooling costs associated with other fossil fuels, including electricity. The systems are quiet, efficient, and carbon-friendly.
For large industrial-sized boilers, economies of scale may be able to justify the production of electricity, in addition to space heat. Michigan pulp and paper mills utilize wood chips to produce both process heat and electricity. These systems could be constructed to provide heat and electricity to entire communities. This is common in many European countries with fewer deployments in the United States. Downtown St. Paul is heated, cooled, and powered by one these systems, using area solid waste streams for fuel.
Like any technology, especially renewable energy technologies, each site will have variable circumstances. In rural northern Michigan, with a vibrant logging infrastructure, wood chip systems are fairly easy to deploy. They use small amounts of wood, compared to regional harvest totals, and help support local economies by keeping energy dollars and jobs within communities.
Wood chip and pellet technologies provide markets for low quality wood products, which are currently more difficult to sell. The absence of a low quality wood market is particularly common in southern Michigan. The ability to remove low quality wood from our forests provides needed options for forest management. More management options can better improve timber quality, habitat characteristics, environmental services, exotic species control, visual quality, and forest restoration.
Use of wood-based renewable energy technologies, especially those for heating and cooling, has distinct environmental benefits beyond expanded forest management options. Wood fuels contain carbon that is already part of the carbon cycle. Displacing fossil fuel use, including natural gas, works to reduce carbon inputs from outside the carbon cycle. Additionally, managed forests result in increased levels of carbon sequestration.
Homeowners, communities, businesses, schools, hospitals, and other building infrastructures may want to explore the possibilities of wood-based heating and cooling technologies when the time comes to replace current fossil fuel based systems. These technologies will not be a good fit in all situations. However, numerous case studies have been in operation for decades and there are several newer conversions. Wood is an abundant, cost-effective, environmentally-friendly way to provide energy for heating and cooling. In so many ways, it makes sense.
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Bill Cook is an MSU Extension forester providing educational programming for the Upper Peninsula. His office is located at the MSU Forest Biomass Innovation Center near Escanaba. The Center is the headquarters for three MSU Forestry properties in the U.P., with a combined area of about 8,000 acres. He can be reached at firstname.lastname@example.org or 906-786-1575.
by Bill Cook, Forester/Biologist, Michigan State University Extension, 6005
J Road, Escanaba, MI 49829
906-786-1575 (voice), 906-786-9370 (fax), e-mail: email@example.com
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