Is Burning Wood For Heat Really Green?


The Stûv that Dreams Are Made of

We love wood at TreeHugger; our posts on wood and pellet stoves continue to be among the most popular we have ever published. Environmental writer Mark Gunther loves it too, calling it A renewable energy technology that gets no respect.. He calls it " a "green" technology that appeals to poor and working class people. And, because gathering and distributing wood is labor intensive, it's generates economic activity."

We also love simple tech, and learning from the past; Mark writes "as is so often the case with environmental or health problems-think about excessive packaging, or overly-processed foods-solutions lie not in some futuristic technology but in the past."

So what's wrong with this picture?
1. Even the cleanest stoves are still dirty.

Marc writes:

The drawback of burning wood is that even efficient stoves produce some particulate pollution, so they should not be used in places like Los Angeles or Denver where smog remains a problem.

That is a bit of an understatement. Even an EPA certified low emission stove puts out enough fine particle pollution in 2-1/2 days as a car does in a year. That's why they have been banned in Montreal and a lot of other cities. They are not suitable for urban areas, period. And at the last census, 80% of the population of the United States was urbanized, so we are really talking a niche market here.


Image credit Global Forest Watch
It doesn't scale.

A rule of thumb from woodheat.org is that " a healthy, well-managed woodlot can yield half a cord of wood per acre per year forever" and that "a ten acre woodlot could sustainably produce enough firewood each year to heat a house." That would mean that if there really are 15 million people using wood to heat their homes in American now, as Marc's article suggests, then they are either getting it from 150 million acres of land, (1/5 of the entire forested area of America) or they are not managing it sustainably.


Image Credit Professor Charles Hall via Wood-heat.org
It still takes energy to make energy

Here is one example of the numbers used to calculate the the energy return on energy invested (EROEI):

  • hardwood fuel example: 24 million btu per cord of sugar maple
  • 1 gallon of gasoline: 115,000 btu
  • average round trip for fuel delivery: 50 miles
  • fuel consumption of pick up truck: 15 mpg
  • two round trips per cord = 6.7 gallons
  • chainsaw fuel per cord: 0.5 gallon
  • log splitter fuel per cord: 1 gallon

If you are harvesting your own wood on your own woodlot, the numbers are better. Scale up the industry and get the wood from farther away, and they get a whole lot worse.


Image credit Rika

America Isn't Europe
Gunther notes that wood heat is popular in Europe; it's true, and TreeHugger is full of images of gorgeous ten thousand dollar wood stoves sitting in stunning apartments. But the article is promoting wood for low and middle income people, quoting John at the Alliance for Green Heat and writing:

Wood stoves are most popular (obviously) in colder climates and (not so obviously) among poor people. Arkansas and West Virginia, for example, are big wood burning states. John says: "It's actually poor people in this country who are at the forefront of not using fossil fuels, and they're doing it without getting any money back."

They are not living in cute little well-insulated apartments, they are probably not using EPA approved low emission stoves, and I doubt the wood is sustainably harvested. Poverty is not green or sustainable.

It's hard.

Even an article entitled The Argument In Favor Of Wood Heating on a website devoted to promoting wood heat summarizes the problems:

Despite its considerable advantages, fuelwood is not a good solution for all households to the problems of high home heating costs and global warming. Fuelwood is not a suitable energy source in all locations, such as densely-populated urban areas, because its air emissions tend to be higher than other options, and the air is already burdened with pollution from industry and transportation. A winter's supply of wood takes up a lot of space, and the price of firewood in urban areas is normally too high to achieve savings. Successful heating with wood also requires a level of physical fitness and the learning of a special set of skills. Clearly, wood heating is not for everyone.

We have noted for years that wood stoves are hot, but are they green enough to merit subsidies and tax credits like solar panels and other renewable energy technologies? I am not convinced. More at Marc Gunther.
More on wood stoves
Wood Stove Emissions Law in Germany
EPA Wood Stove Changeout Campaign
Pellet Stoves vs. Wood Stoves: Which Is Greener?

Best of TreeHugger