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Last week I was a guest in my colleague’s Renewable Energy Law class.  One of the questions I was asked had to do with Maine’s Renewable Portfolio Standard (RPS).  Maine’s RPS seems, at first glance, to be an ambitious goal (40 percent of Maine’s electricity is to come from renewable sources by 2017). However, at the time the RPS was made law, Maine was already mostly meeting that goal, thanks to Maine’s booming woody biomass industry. 

Other states in the New England Power Network can help fulfill their own RPS by purchasing renewable energy certificates (RECS) from other states in the network.  If a particular unit of energy is produced by a renewable source, that unit of energy could earn a REC, which could then be sold elsewhere.  However, even though every state in New England has a RPS (except Vermont, which has a goal), they don’t all accept the same types of energy for their RPS. Hence, there are some RECS that can be sold in some states, but not others.

Maine is the only state in New England that accepts biomass and large scale hydro to help fulfill its RPS. Therefore, any biomass facility that produces RECS can only sell them in Maine. In a report that came out detailing the performance of Maine’s RPS during the past year, a good 95% of the  Maine RPS was met through RECS generated from biomass.  And the fact that biomass credits can only be sold in Maine will depress the price of those credits -leading to less revenue for those facilities.

Which lead to one of the students’ questions: why don’t the other states accept biomass?  It’s a good question.  Leaving aside the (obvious) conclusion that Maine accepts biomass as an energy source in order to prop up its ailing wood products industry, why would other states not accept it? Isn’t biomass a renewable source of energy? And isn’t it carbon neutral ?

The answer, as any good economist knows, is “it depends.”  (My father used to say -paraphrasing Harry Truman – that what the world needs is a one-handed economist, because we’re always saying ”on the one hand….  But on the other hand…” ) Biomass is certainly a renewable source, in the strict physical sense that the “fuel” used – plant matter – is renewable.  The time it takes to regenerate, of course, depends on the growth rate of the plant matter used.

But there’s also no escaping from the grim third law of thermodynamics – that matter (or energy) can neither be created nor destroyed.  It takes power to make power.  How efficient the energy source is depends upon the energy content of the fuel and the energy used up in the process of making it.  Think lifecycle analysis.  If a unit of energy generated requires two units of energy in order to generate it, then that source isn’t really renewable – is it?

UPDATE: As my colleague Bill Strauss of FutureMetrics points out, “Every solid or liquid fuel whether coal, pellets, gasoline, diesel, natural gas, etc., gathers a carbon footprint from mining, extraction, refining, transport, etc.  Only biomass, if the net carbon stock is not depleted (i.e., the growth rate equals or exceeds the harvest rate), captures the CO2 from combustion contemporaneously…  Wood pellets are a low carbon solution… they are carbon neutral in combustion but are not carbon neutral over the supply chain.  Of course neither is anything else that depends on fossil fuel for transport etc.”

Absolutely, Bill, and thanks for that. (So people actually do read this stuff…) Check out their website!

Biofuel can be made from a number of things: corn, switch grass, trees, wood  manufacturing waste, to name a few.  And there are a number of ways biofuel can be produced – burned, fermented, digested by bacteria, or “gasified.”  The energy content of the fuel as well as the energy input needed vary widely for each process. 

As for whether it’s carbon neutral – well,  anyone who makes that claim is doing some pretty funky carbon accounting.  In the sense that the carbon released when the tree is burned is the same amount of carbon that was “stored” in the tree – then yes. But what about the carbon used in harvesting the tree?  Getting it to the processing site,  and from there to where it will ultimately be used? There’s also the fact that trees uptake carbon at different rates in their lifecycle, and that different species of trees uptake carbon at different rates. So for it to be carbon neutral, the net stock of carbon in the forest needs to remain unchanged. It’s possible, but it’s not as simple as “cut a tree, plant a tree.”

What about the claim that it’s sustainable? Again,  it depends.  If the trees are harvested at the same rate they regenerate, then yes. And, Maine’s biomass is mostly from residue from the forest products industry, so the use of waste product for energy gets a thumbs up in my book.

Recently,  two major biomass facilities in Maine went offline,  alarming the logging industry and others in the forest products supply chain. It also should alarm environmentalists.  The decline in oil prices has not only boosted demand for oil,  but depressed demand for biomass and other renewable sources of energy. Biomass may not be a perfect source of energy,  but it needs to be part of the energy solution in Maine.