Cutting down trees for biofuels?

Lynne Kiesling

Cutting down trees to generate biofuels to substitute for fossil fuels can’t make sense in terms of carbon accounting, can it? I never thought so, but apparently some people have contended that it does. This Project Syndicate essay from Bjorn Lomborg addresses the question, and I think it’s worthy of consideration not just because I think his argument is persuasive (which may reflect the quality of the argument or my confirmation bias, take your pick), but also because he provides several links to published papers that suggest that such strategies may actually increase GHG concentrations.

His point is more important and more subtle, though. What happens when deliberate cultivation of biomass crops changes the land use and moves agricultural production to other plots of land?

But the biggest problem is that biomass production simply pushes other agricultural production elsewhere. Studies are just beginning to estimate the impact. In Denmark, a group of researchers estimated by how much various energy crops would reduce CO2 emissions. For example, burning a hectare of harvested willow on a field previously used for barley (the typical marginal crop in Denmark) prevents 30 tons of CO2 annually when replacing coal. This is the amount that proud green-energy producers will showcase when switching to biomass.

But burning the willow releases 22 tons of CO2. Of course, all of that CO2 was soaked up from the atmosphere the year before; but, had we just left the barley where it was, it, too, would have soaked up quite a bit, lowering the reduction relative to coal to 20 tons. And, in a market system, almost all of the barley production simply moves to a previously unfarmed area. Clearing the existing biomass there emits an extra 16 tons of CO2 per year on average (and this is likely an underestimate).

So, instead of saving 30 tons, we save four tons at most. And this is the best-case scenario. Of the 12 production modes analyzed, two would reduce annual CO2 emissions by only two tons, while the other ten actually increase total emissions – up to 14 tons per year.

Rather than displace agricultural production (with all of the attendant distortions in other markets that would arise), I tend to think about doing research in and exploring technologies for biomass waste recycling. Things like anaerobic digesters to process dairy waste and use it to generate electricity. In that case you are generating two benefits — electricity for consumption and waste management — so the combined value of those two benefits may make a more costly technology economical. Here are some suggestive numbers about that net benefit from Wisconsin, although I caution putting too much credence in them.


7 thoughts on “Cutting down trees for biofuels?

  1. I’m pretty convinced that an accurate carbon output and environmental impact accounting of policies put in place to reduce carbon emissions would clearly show that these policies have:

    1. Caused higher carbon emissions then the do nothing alternative
    2. Increased environmental damage over the do nothing alternative
    3. In general caused more harm to ecosystems and humans then the do nothing alternative

    On the plus side these policies:

    1. Made money for politically connected cronies and provided benefits to their politician allies
    2. Allowed environmentally ignorant carbon activists to feel good about supporting policies that increase harm to the environment

  2. County government has been promoting manure digesters in the Madison area for disposing of manure waste as an alternative to spreading it on fields and to indirectly encourage growth of giant dairy farms (which cause lots of runoff problems in the lakes), then subsidize the manure digesters.

  3. Everything like you said goes along with “selective statistics.” They will point out the carbon dioxide saved, but n fact they do not look at other relative factors tht mke this just ditching fom green apples to red apples. The crucial point to look at when looking at this subject matter, ie, new fuel sources, environmentalism, conservation, saving the earth, is to see that the only side being presented is the “humanist” perspective. “What can be one to help this planet be most sustainable for US,” is more practical (but far less responsible) than say, what can be done to make this planet most hospitable to all the creatures here?
    When thinking and action is taken into account from this perspective, each will realize the responsible thing to do isn’t to live to 95-100, have 3 kids, all of which eventually drive new cars, but new homes, travel on airplanes here and there, and consume consume consume. The answer is slowing down, eliminating the need or all kinds of parental government, getting back to our roots, finding True meaning in our lives, and loving every creature as much as the human race.

  4. The vast majority of biomass electricity and heat is produced from waste materials such as sawdust, bark, slash, storm debris, log-ends, etc. These are materials that decompose rapidly or would otherwise be burned in open piles. So there is an un-arguable climate benefit to recovering the energy in these materials.

    The question of purpose grown energy crops or tree-crops is an interesting one, but largely a hypothetical one. I have yet to see, here in the United States, any energy facility regularly consuming whole trees or purpose-grown biomass. It’s just not happening. I’ve looked for it. The marginal economics of these operations won’t allow it. (The only situation allowing it today is the export of wood pellets from the US to Europe and the UK, a situation made possible by the lack of carbon policy here in the US, as well as an oversupply of cheap pulpwood and timber, due to decline of paper, pulp, and housing industries.)

    However, many projections of renewable energy and biofuels predict that we will SOMEDAY need energy crops or short-rotation woody crops. So let’s go with this hypothetical for the moment.

    It is NOT a foregone conclusion that these crops would be grown on land that currently produces food. On the contrary, most industry standards or statements of principle rule-out such land-use changes as they would raise the dread “food-vs-fuel” dilemma.

    Also, it is becoming increasingly clear that mere carbon-neutral mitigation measures will be inadequate to the kinds of GHG reductions needed to stop global warming at 2 degrees Celcius. In fact, the Global Energy Assessment (Source: see Figure TS-7) shows that about half of global decarbonization models say we must not only decarbonize our energy systems, but we must also begin sucking carbon out of the atmosphere and storing it somewhere safely.

    Biomass is the only renewable energy source that can go carbon negative. It does this by the co-production of biochar. The 2009 paper “Sustainable Biochar to Mitigate Global Climate Change” was an extremely conservative attempt at quantifying the role this technology might play in running the big carbon-spewing machine backwards.

    This is not pie-in-the-sky: For two current examples of carbon negative bioenergy production, google Cool Planet Biofuels and Burt’s Greenhouses Biochar.

    The key fact about biochar visavis the land-use change question is that biochar helps increase the productivity of marginal soils. Done properly, biochar could actually EXPAND the numbers of acres available for food production, while also delivering bioenergy that our society needs. Dreams of deserts on the retreat are not entirely far-fetched.

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