Column: Biomass opposition understandable — and wrong

For the Valley News
Published: 11/8/2019 10:10:52 PM
Modified: 11/8/2019 10:10:38 PM

I am strongly in favor of Dartmouth College’s proposed biomass heating project, though it is not hard for me to understand why others feel differently. Wood energy is a nuanced subject, more so than most people realize. Some may read a study that addresses one place, time and application of wood energy and they apply that study’s findings to all forms of wood energy.

For instance, the Dartmouth proposal is often compared to the production of wood pellets in the southern U.S., which are then shipped to the huge Drax power plant in England or elsewhere in Europe. Those who oppose the Dartmouth project often suggest watching Burned: Are Trees the New Coal?, a well-produced documentary full of scary music, smoky air and images of clear-cuts that attempts to raise money to stop this transfer of wood to Europe. For the unknowing, dread feelings about wood energy would be hard to avoid after a viewing.

In reality, the Dartmouth project has almost nothing in common with what is seen in that documentary.

There is an enormous efficiency difference between power plants and heating plants. Heating plants are about three times more efficient than power plants, which makes a huge difference in carbon dioxide emission calculations. I have also seen many comparisons to residential wood stoves. Comparing the combustion controls on a chip boiler like the one Dartmouth would use to a home wood stove is like comparing a modern automobile to a horse and buggy. When special interest groups create extreme data examples as scare tactics, they are often comparing apples to oranges.

As an aside, the wood chip component of the proposed Dartmouth plant is 16 megawatts. The other (32 megawatt) boiler would use a liquid biofuel, which would have similar particulate emission characteristics to No. 2 heating oil, but likely without a sulfur component. This component of the project rarely enters the conversation, which to me is indicative of the narrow-mindedness of some project opponents.

It is easy to assume the worst about wood energy because there is smoke and the harvest of fuel is easy to see. Cutting trees, especially for those who have not witnessed a harvest, can be shocking. But I suspect that some of the same people who disdain wood burning are thrilled about their electric cars — while completely overlooking the destruction caused by the lithium and cobalt mining required to produce those cars.

The beauty of wood is that it is right here where we can see it. It is actually possible for Dartmouth officials to keep a close eye on the wood being brought to their facility, which is more than can be said for most other fuel sources, including natural gas or vibrating electrons in a copper wire.

For heating, the most ecologically attractive alternative to wood is heat pumps, which might work in some buildings at Dartmouth. There are several problems with heat pumps, however. First, when renewable power is at its lowest output (at night during winter, for example) and heat pumps are at their lowest efficiency (assuming air-source heat pumps), heat demand is highest. Ground-source heat pumps do not lose efficiency as outdoor temperatures decrease, but installation costs are far higher.

Second, the output temperature of heat pumps is quite low, about 120 degrees Fahrenheit. Dartmouth buildings would need massive and cost-prohibitive internal upgrades to both insulation and heating distribution systems in order to make heat pumps a possibility in all Dartmouth buildings.

Third, heat pumps are not a renewable energy source. They are basically reverse refrigerators. And while they are an efficient user of electrical energy to produce heat, Dartmouth would still have to find enough renewable power — either through its own facilities or through renewable power purchases — to justify the use of heat pumps.

Some people have said that Dartmouth should install solar panels to heat its campus or provide solar power for heat pumps. If the college covered its entire five-acre green with solar panels, it could make about 3.1 megawatts of renewable power while the sun is shining — and consider how often the sun shines in Hanover in the winter. But the boilers that heat Dartmouth’s campus would produce a combined total of 48 megawatts. Dartmouth will have enough trouble producing renewable power to cover its existing electrical loads without also finding enough power for thermal loads.

All of that said, it is true that burning wood emits more particulate emissions than liquid fuels. But I believe the dangers of particulate emissions from the proposed Dartmouth plant are overstated by the interest groups that are sowing doubt. The Dartmouth facility may use “multi-cyclones” to remove particles down to 10 microns or so, and there will also likely be an electrostatic precipitator, or ESP, which uses static electricity to capture particulates down to about 2.5 microns, the size that is so dangerous to the lungs. The capture rate of ESPs is usually 98% or better.

Also, the toxicity of particulates from modern wood-burning equipment is very low. Low-tech or poorly burned fires emit an aerosol tar full of toxic organics. Modern equipment, especially automatic chip and pellet burners, burn almost all of that aerosol tar. The otherwise harmful particulates are burned within the combustion chamber producing inorganic ash, which has a low toxicity. Some fear that heavy metals will be showered down upon the community. That is highly unlikely. There is very little heavy metal in wood, if any. Modern boilers also have very low carbon monoxide emissions, often rivaling that from liquid fuels. And there is no sulfur, which is a prominent component of coal, No. 2 and No. 6 oil emissions.

It is also true that burning wood emits more carbon dioxide at the stack than other, more energy-dense fuels such as coal, oil and gas. This seems like a major problem at first glance, but what is lost in this argument is that wood harvesting and chipping requires very little energy input compared with all other fuels Dartmouth could use. Think about how much energy it takes to refine oil and gas and then transport that fuel. People are quite comfortable with the “Eat Local” mantra, but seem to be unable to apply that to “heat local.” Yet nearly all of the same arguments apply.

In Northeastern forests, we have a large supply of sustainably harvested wood. Wood stocks are growing faster than they are being harvested. Studies that describe deforestation, species loss and contaminated water from tree harvesting do not apply here.

On the contrary, we lose 65 acres of forest a day in the Northeast to agriculture and development — not forestry. If people cannot realize an economic value in their forest they are likely to sell it for other purposes. The impact is severe. Not only do we lose trees, but forest parcels become fractured. This is massively destructive to the ecology of a forest.

Our local forests, even with regular harvests, have been absorbing carbon dioxide faster than we are harvesting for decades. With active forest management we can capture even more carbon while still harvesting plenty of fuel. Dartmouth commissioned a study that affirmed there is ample wood. We sure can’t afford to risk our forests to development. There is much more than carbon at stake — clean water for one thing.

When walking across a wooden floor, sitting at a wooden table, or using solid wood products of any type, it is worth considering that about three times as much waste wood was created during the harvest of that wood as is used in the finished product. That waste wood requires markets. Fuel is a perfect market in this region.

Scott Nichols, of Lyme, is the owner Tarm USA in Orford.




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