Saturday, October 30, 2010

Biofuels Reduce The Biosphere's Capacity to Absorb Carbon



Brace yourselves for another thought exercise.

Expanding Croplands Chipping Away at World's Carbon Stocks
:

The conversion of the planet’s ecosystems into cropland — particularly in tropical rainforests — is stretching the Earth’s ability to store carbon, according to a new study. The demand for new agricultural land is growing most rapidly in the tropics, due to growing populations, changing diets, food security concerns, and a rising demand for biofuels.


Tim Searchinger is a researcher who has been published in the prestigious journal Science at least five separate times by my count. His, in hindsight, rather obvious, common sense observations have become a serious thorn in the side of the biofuel industry.

He was one of the first to raise the alarm about indirect land use issues (using corn for ethanol sent a price signal to clear more farmland from carbon sinks). He was the first to point out that government subsidies for biomass will aggravate global warming by motivating people to cut down trees. Burning trees to make electricity will release their carbon into the atmosphere. The seedlings planted to replace those trees will take decades to remove that carbon and store it again. Meanwhile, the CO2 from the trees that were burned will heat the planet for decades. We don't have decades.

Because of the great potential for profit, attention has focused on technology (hybrid and electric cars, solar, wind, nuclear, biofuels, and biomass) that will release less CO2. Very little attention has been paid to the other half of the global warming solution (getting the excess CO2 back out of the atmosphere) because nobody has figured out a way to get rich by just leaving forests and grasslands alone.


Photo by Mongabay

Case in point, Mongabay has an article up titled Scientists blast greenwashing by front groups:

The Consumer Alliance for Global Prosperity (CAGP) is a new group based in Washington D.C. that has launched a campaign against American firms that have adopted sustainability criteria in their sourcing policies. Companies targeted consist mostly of retailers that have dropped APP [Asia Pulp & Paper] from their stores, including Office Max, Staples, and Office Depot, but not Walmart, which has cut ties with APP except for its Walmart China division. The Consumer Alliance for Global Prosperity claims that these corporations are colluding with unions and "radical environmental activists" to hurt consumers in the United States.

"The 'Empires of Collusion' continue to push an anti-prosperity, anti-trade agenda," CAGP says in its campaign materials. "This coordinated campaign is run by radical environmentalists and others against the producers of pulp and paper from the developing world, destroying the livelihoods and aspirations of thousands of the world's poor."

"This initiative will fight back against anti-trade, anti-prosperity collusion among international Green NGOs, American trade union bosses, and corporations looking to eschew the rigors of a competitive marketplace."


How much a given biofuel reduces production of CO2 depends on how much fossil fuel is used to make that biofuel. No crop-based biofuel is carbon neutral. Cane ethanol and palm oil biodiesel come the closest but they all increase greenhouse gases to one degree or another.

But, unlike fossil fuels, the usurpation of water and arable land to grow biofuels inversely impacts our ability to allow forests and grasslands to remove the CO2 that's already in the atmosphere (as well as the CO2 being added with each gallon of biofuel burned). This is an extra downside to biofuels that fossil fuels don't share. Put another way, today's crop-based biofuels are hogging up the land and resources we need to store carbon.

In a nutshell, agrofuels are a dead end idea, a dog barking up the wrong tree. There are many ways to reduce CO2 production other than simply exchanging gallon for gallon the fossil fuels in our gas hog cars for liquid fuels made from the rapidly unraveling fabric of our biosphere.

We must reduce CO2 production while increasing CO2 absorption: Absorption/Production > 1, or Production < Absorption.

Until some biological process absorbs it, CO2 tends to stay put. Plants are the only means we have of removing excess CO2 from the air and safely storing it as carbon. In theory, if we could grow enough plants we would not have to cut back on fossil fuel use to avoid global warming because those plants would absorb and then store all of the CO2 produced by the fossil fuels. This would require roughly tripling the amount of land covered by forest and grassland. Unfortunately, that much water and unused arable land does not exist.

And keep in mind, those plants have to be alive to store carbon. They can't be used for fuel, or food (which is fuel for people).

The biofuel lobby appears to have concluded that this is one argument they are not going to win so they have switched tactics. No longer do they mention greenhouse gases or global warming in their press releases. Instead, they stick to exaggerating claims of clean air and job creation, while fanning the flames of xenophobia by suggesting corn ethanol is a stepping stone to energy independence (when in reality, it has hogged up all of the market leaving nothing for potential next generation fuels).

It seems that few people are interested in just leaving forests and grasslands alone to absorb carbon. The whole idea seems somehow wasteful. Where's the money in that? Global warming is essentially a shot across the bow warning us that we have finally exceeded a planetary limit. Speaking of which, and as icing on the biofuel cake, biofuels are also exacerbating other planetary limits.

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9 comments:

Paul N said...

It would seem then, that if we are going to have sustainable biofuels, that they should come from forests, like they once did.

Surely there is a way to do that, without logging style clear cutting, or monoculture hybrid poplar plantations, that can maintain a healthy forest and provide a continuous supply if fuel.

We just have to accept that it will be less ton/ac/yr than clearing and "managing" a plantation, but so be it.

Here in Canada, most logging happens on public land, and, unfortunately, is mostly clear cut. The government is considering alternative licensing for biofuel harvesting, which would be for non clear cutting methods. Of course, this could still be done in a way that is either good or bad for the forests, but could hardly be worse than clear cutting.

The inputs and management (and profit for Monsanto etc)are minimal compared to farming, but that's the beauty of it!

Russ Finley said...

Well, the problem is that we have to expand carbon sinks to pull carbon out of the air. Using trees for fuel defeats that plan unless you plant vast amounts of new trees and allow them to mature prior to burning any of the existing.

It takes decades to pull the carbon back out of the air from a decades old tree that you burn.

All academic I suspect. Humanity is tightly wedged between a rock and a hard spot.

Paul N said...

" the problem is that we have to expand carbon sinks to pull carbon out of the air. "

Not quite. For a mature (steady state) forest, much of its carbon is released back to atmosphere as vegetation composts, particularly in warmer latitudes.

If, for example you removed the woody portion of the deadfall, you would be removing carbon (for other uses) while the forest carried on. It will change the dynamics on the forest floor somewhat, although looking at some of the cedar forests around here, there forest floor is devoid of life anyway - all deadfall and ages worth of leaf litter, but bone dry and nothing growing.

if you were to remove 10% of the standing trees each year (at average age ten years), then the forest will close that gap with new growth. A bit like a large scale version of maple syrup making - you extract enough to get a useable product, but not so much as to endanger the tree.

A neighbour of mine has a half acre property, covered in trees except for their house. Each year, they take down enough trees to make two cords of firewood, enough for their winter (650sq.ft house). They have been doing this for ten years and their observation is that the "forest" is thicker than it was when they started, and the trees seem healthier, as they always take out the older ones (not all of them, they leave some to seed, and for birds etc). They have a good variety of Firs, Cedar and Red Alder (a nitrogen fixer), and no shortage of birds and squirrels - so I would say that is a good forest.

Two cords is only two tons of dry matter per year, form half an acre (actually, about a third), which implies a yield of six dry tons/ac/yr. I think that is a pretty good sustainable yield.

Of course, this cycle is carbon neutral, but we are getting energy out of the flow. And all the ashes get scattered back on their trees. They haven't yet worked out how to do that with the sludge from their septic tank, but they did "intercept" the drain field and run distribution lines among their trees.

All in all, a neat little system. I'm sure it could be reproduced on a larger scale.

Russ Finley said...

"For a mature (steady state) forest, much of its carbon is released back to atmosphere as vegetation composts, particularly in warmer latitudes."

True, but I'm not talking about mature old growth forests. Your neighbors don't have a mature old growth forest. Their harvest is slowing carbon storage except where the thinning increases growth rates. It's better than burning fossil fuels from a carbon added perspective but won't scale up very far. We need carbon storage.

If you can find a mature old growth forest to harvest dead and down wood, or wood thinnings from, great. Although, most of the biodiversity of a forest is found in its floor and soil. That dead wood provides habitat and food for millions of species. Termites love it and lots of species love termites. We can't be turning old growth ecosystems into sterile tree parks.

Heating with wood also tends to produce a great deal of soot. Soot does not get much press but it is also a problem:

"Soot accounts for 18 percent of greenhouse gas emissions, second only to carbon-dioxide (CO2), which accounts for 40 percent of the emissions blamed for global warming ..."

I own eleven acres of forest that I'm allowing to return to old growth.

Paul N said...

No, it's not a mature forest, about 40yo 2nd growth, as is my entire area, with the very odd remaining old tree (one blew down 3yrs ago that was 400yrs old and 8ft at the trunk!).

But that does not mean it is not sequestering C at a rate equal or greater than old growth forest.

Once a forest does reach "maturity", the rate of carbon storage decreases , as there is no increase in standing biomass, only the remnants after composting of deadfall on the ground.

Best number I can find for boreal forest is 2.4t/C/ha/yr (1tC/ac/yr)
"NEP estimates suggest that forests 200 years old and above sequester on average 2.4+0.8 tC/ha/y: 0.4 +0l1 t in stem biomass and 0.7+0.2 t in coarse woody debris, which imply that about 1.3+0.8 t are in the roots and soil organic matter."
(source: http://www.i-sis.org.uk/oldgrowthforestcarbonsink.php)

So they get 1.1tc/ha/yr from above ground stuff, which translates to 2.2tons of (dry) wood. A young forest can easily produce 10 dry tons/ha, and under "management" can produce 20t/ha/yr.

If we wanted to maximise carbon storage, we would keep the forest where the trees are at their fastest growing age (most biomass/ac/yr) which is around 7-15yr old trees, and then harvest some each year.
If that harvested wood is burnt for energy, there is not carbon storage of course. But if it is used for wood products, (lumber) then it is effectively sequestered.

If we get 10 dry tons/yr of wood, we are getting at least 7 tons in the roots - which is 3.5 tons of C. So even the roots alone are sequestering C 50% faster than an old growth forest, and we haven;t even done anything with the wood yet. Sequester all the wood, and you would have 5tons of C per year, for a total of 8.5 - more than 3x the rate of mature old growth forest.

So, I will maintain that there is a point where we can use the forest for something, which still maintaining or even increasing rates of C accretion. It is just that almost no forests/plantations are being managed like that today.

Too bad about the brush collectors on your 12acres - sounds good otherwise. You know that in Japan, unauthorised removal of anything from forest is a serious offense, and seriously enforced. That's probably a large part of the reason why Japan is one of the most forested countries in the world.

Russ Finley said...

"So, I will maintain that there is a point where we can use the forest for something, which still maintaining or even increasing rates of C accretion. It is just that almost no forests/plantations are being managed like that today."

And I will cede that point to you, good sir.

Paul N said...

For the record Russ, I am a proponent of leaving the remaining pockets of old growth forest as exactly that. My view on using the forest only applies to the parts we have already abused - which, sadly, is the majority of it.

But I do think "forest farming" is much more sustainable than 'conventional farming", though it will not produce as much food, and will need more labour to do so. A more organised and environmentally conscious version of your brush pickers, driving EV's or ebikes, of course.

Anonymous said...

Obviously the author and the individual still posting this article have no concept of 2nd generation feedstock.

The only reason to chop down forest for biofuel was for 1st generation feedstock.

All viable biofuels today are from orchards. There are thousands of companies around the world planting billions of trees.

Please catch up with current technologies and solutions so readers do not get the wrong information and perspective.

etcgreen.com

Russ Finley said...

I think you missed the gist, anonn. Planting an "orchard" and then burning it, does not store carbon. The carbon in the atmosphere has to go somewhere other than the oceans which are becoming more acidic:

"...But, unlike fossil fuels, the usurpation of water and arable land to grow biofuels inversely impacts our ability to allow forests and grasslands to remove the CO2 that's already in the atmosphere (as well as the CO2 being added with each gallon of biofuel burned). This is an extra downside to biofuels that fossil fuels don't share. Put another way, today's crop-based biofuels are hogging up the land and resources we need to store carbon...."