Heat and Boilers
Article #243, December 2016
By Bill Cook
Now that the winter solstice is around the corner, we’re all aware of the need to heat our living, shopping, and working spaces. This requires some sort of fuel and the vast majority comes from non-renewable fossil fuels. Alternatively, the Lake States have a huge and increasing wood inventory. So, there exists a tremendous untapped potential for producing sustainable and renewable heat.
Almost everyone is aware of old-fashioned fireplaces, wood stoves, and outdoor wood boilers. These devices offer benefits to the residential user. Sometimes, there are air quality issues associated with the devices, often due to the use of wet fuels and excessive damping of the air flow. However, there are a range of advanced, highly efficient, and very dependable technologies for residential, commercial, and institutional applications, especially for schools, hospitals, municipal facilities, and similar structures.
Advanced wood chip systems work well when heating spaces of more than about 50,000 square feet, although this breakpoint is not set in stone. Capital costs of advanced wood chip systems are higher than those for fossil fuel systems, but operating costs are lower. Current low prices for natural gas have increased the payback period for wood chip systems, if there is access to natural gas.
One of the nation’s premiere wood chip heating system manufacturers is based in the Upper Peninsula of Michigan. Messersmith Manufacturing has built, delivered, and installed over a hundred institutional-sized systems around the country.
An important factor when considering a wood chip system is identifying local wood chip suppliers. Not all areas of the Lake States have ready access to contractors with wood chippers. Determining the quality of available chips is a critical factor in designing a wood chip system. These systems are often the least expensive heating alternative available but a thorough feasibility study is necessary to be certain.
Smaller spaces may be better heated with wood pellets or cordwood. Wood pellet systems have their greatest potential for residences and small businesses that are off the natural gas grid. In Michigan, roughly a third of all households heat with propane, fuel oil, or electricity. Advanced wood pellet stoves, furnaces, and boilers offer a less expensive alternative and are equally as reliable and convenient as fossil fuel systems.
One of the current hurdles in expanding wood pellet heat is the lack of a bulk delivery service, which is common in the more advanced renewable energy economies. Similar to fossil fuel deliveries of propane or fuel oil, trucks supply wood pellets once or twice each heating season. All the homeowner needs to do is move the thermostat.
For rural locations, there are a wide range of modern cordwood boilers and indoor stoves that heat homes, small businesses, and resorts. The critical question is how much wood is a user willing to process? And, is the user willing to keep these home fires stoked on a daily basis?
When the wood supply is gathered from the forest by the user and the cost of that labor is chalked-up to recreation, these systems are quite inexpensive. If cordwood is purchased, the costs are typically below that for propane, fuel oil, and electricity, but not necessarily that of natural gas.
On a community scale, groups of buildings can be heated (and cooled) from a central boiler plant connected to a piping network. These “district energy” systems are highly efficient and deliver the least costly heating and cooling. Downtown St. Paul, Minnesota, is heated and cooled with a district energy system fueled on municipal solid wood waste. In southeastern Michigan, Bordine’s Grand Blanc plant nursery facility uses a district energy system to heat over 11 acres of greenhouses.
There is a wide variety of designs available to provide low-cost, dependable, and clean renewable thermal energy from wood-based fuels.
Two of the more common concerns about wood-based thermal energy involves our forest inventories and atmospheric carbon.
The Lake States wood volumes have been increasing for a century. Michigan has one of the highest rates of annual growth in the nation, more than twice that of mortality and removals. So, while forests do, indeed, have limits to wood supply, there is no current shortage of wood. There is room to expand the wood heat sector.
The issue about wood supply is more about availability than inventory, an important distinction. Our forests offer a great opportunity for contributing to our economy and sustainable communities, while at the same time increasing environmental benefits and healthier forests.
Carbon additions to the atmosphere are sometimes cited as concerns in the face of climate change. However, you can burn trees for fuel for a thousand years, or a million, with no increase in carbon within the carbon cycle. The carbon from burning wood came from the atmosphere just a short while ago. In fact, managed forest landscapes actually sequester more carbon than unmanaged forest landscapes.
On the other hand, no matter how little fossil fuel you burn, atmospheric carbon dioxide (CO2) will be increased. It is true that, compared with wood, burning fossil fuel may produce less CO2 for the amount of energy received, but that is irrelevant because wood is already part of the carbon cycle and fossil fuel carbon is not.
Are you interested in learning more about wood-based thermal energy? If so, contact the Statewide Wood Energy Team at “Michigan Wood Energy”. If you’re going to warm yourself with a fire, it’s always better to burn above-ground, plant-derived carbon than that long-buried underground.
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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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