Get Rid of Coal and Use Trees Instead, Urges Hansen
by Jeremy Elton Jacquot, Los Angeles on 09.14.08
Image from *Micky
It's not a sure-fire bet, but NASA climate scientist James Hansen and several colleagues have published an article in the latest issue of Global Biogeochemical Cycles making the case that curbing coal emissions alone could forestall a full-blown climate crisis. While they also recommend reducing the use of oil and gas, they estimate that phasing out coal, which has accounted for roughly 80% of emissions growth since the pre-industrial era (and still contributes a healthy slice), over the next few decades could prevent the planet from entering a prolonged period of climate change.
Instead, humans should grow more trees and burn them to produce electricity, capturing and storing the carbon dioxide generated during the process to further mitigate the environmental toll, Hansen told The Independent's Geoffrey Lean.
Image from DanieVDM
Phasing out coal, planting more trees
He also told Lean that all coal plants should be phased out by 2030, at the latest (unless they're retrofitted with carbon capture and storage (CCS) equipment), and that atmospheric carbon dioxide levels should be capped at 350 ppm; the current level is 385 ppm. Widespread implementation of CCS technologies could stabilize the CO2 level around 400 ppm, he believes, after which an international tree planting initiative, paired with better agricultural practices and more CCS, could bring levels to 350 ppm within a century.
Five emissions scenarios equally grim
To reach this conclusion, Hansen and his co-authors devised a set of 5 different emissions scenarios, spanning the years 1850 to 2100 -- each of which reflected a unique fossil fuel peak production scenario:
The remaining three scenarios include the phaseout of coal, but consider different scenarios for oil use and supply. One case considers a delay in the oil peak by about 21 years to 2037. Another considers fewer-than-expected additions to currently proven reserves, or taxes on emissions that makes fuels too expensive to extract. The final scenario looks at emissions from oil fields that peak at different times, extending the peak into a plateau that lasts from 2020-2040.The team used a mathematical model to convert CO2 emissions from each scenario into estimates of future concentrations in the atmosphere. The "business as usual" scenario resulted in CO2 that would exceed 450 parts per million from by 2035, and climb to more than double the pre-industrial level. Even when low-end estimates of reserves were assumed, the threshold was exceeded from about 2050 onwards. However, the other four scenarios resulted in CO2 levels that peaked in various years, but all fell below the prescribed cap of 450 parts per million by about 2080 at the latest. Levels in two of the scenarios always stayed below the threshold.
Via ::The Independent: Phase out coal and burn trees instead, urges leading scientist (news website)
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I'm all for growing more trees, but is that really what would happen? Would American industry have the patience to farm trees effectively, or would they just hurry up and gut the rest of the national forests?
I read recently that just 14 countries have 92% of the world's forests, and America's certainly on that list. I'm not sure encouraging the government to cut the ones that are left is a good plan.
If we could really get sustainable tree farming underway, then great. Otherwise, it's 1 step forward, 1 step back.
Doesn't have to be trees either, does it? Couldn't you use bamboo or something else comparably quick-growing, where climatically appropriate? The rates of carbon uptake should be comparable for any woody plant. Of course, paulownia trees grow really fast too.
Great article, planting trees is the best way everyday people like me can help reduce carbon footprint. And use the trees instead of carbon should is a great idea. I also give trees instead for gifts, there is a good site http://www.treesinstead.com
The early European settlers practiced coppice forestry for fuelwood. This involves cutting young trees every 10 years are so, such that the root structure is young and vigrorous enough to rebound and quickly resprout trunk growth. Trees could be coppiced 3 or 4 times on the same root system. They literally recycled the root systems!
Details in Eric Sloane's book, Treasury Of Early American Tools.
There are a few issues with this.
1. Planting trees, harvesting them, transporting them, and burning them: What's the EROEI on that?
2. Doesn't this still rely on an underlying fossil fuel economy to make it viable?
3. What's the efficiency on plants that do this?
4. What would you do with the hundreds of tons per day of ash this creates?
5. Wouldn't this use up valuable land that should/could be used for more useful tings, like crop production?
Actually, coppice forestry was discussed in From Coastal Wilderness to Fruited Plain by George Whitney, another great history of the natural world of America.
JSD - ash is a fantastic fertilizer. Its the best way to recycle minerals!
Doesn't burning wood create air pollution? Why not plant the trees, let them grow, and use wind/solar/hydro/etc instead?
It's good to read the generally positive response here to Hansen's seminal proposal, particularly as coppice energy has been my passion for over 20 years.
WRT to questions posed above, here are some answers that will I hope be helpful.
1. Planting trees, harvesting them, transporting them, and burning them: What's the EROEI on that?
The EROEI will depend on the technologies used primarily - for comparison, an operation using machetes, ox-wains and village-scale refinery/power plant will have far better EROEI than a 100MW station supplied by 40T lorries from a huge catchment with automated mobile felling vehicles.
Our goal locally here in Wales is to use chainsaws in the coppices (eventually running them on coppice-sourced methanol, serving a village-scale local refinery by tractor or, if required some day, by ox wains..
2. Doesn't this still rely on an underlying fossil fuel economy to make it viable?
No, it doesn't necessarily rely on the fossil fuel economy, but like all new developments from sus en. techs to websites, it will do so at the outset.
To put this in perspective, in the early C17 the largest industrial plant on the planet was at Backbeck in Cumbria, where iron ore was imported (sail-powered) from Sweden and smelted over coppice-charcoal to make iron & steel. Coal only took over later due to its huge potential for economic growth.
3. What's the efficiency on plants that do this?
Reducing wood to gas (via pyrolysis) to fuel a combined cycle gas turbine, which in turn serves a CHP plant, will yield better than 80% thermal efficiency.
4. What would you do with the hundreds of tons per day of ash this creates?
The woodash must return to the coppices to maintain their fertility. Notably, the small stick & twigs should remain in the coppice for the same reason.
5. Wouldn't this use up valuable land that should/could be used for more useful tings, like crop production?
Establishing new coppice should certainly not be at the expense of farming, but rather should be complementary, using shelter-belts to raise yields and taking poor or unproductive land such as stony or bracken-infested hills, north-facing slopes, marshy ground, high moorland, etc.
6/. Can Govt (or corporations) be trusted to plant anew rather than mining out old growth Forest ?
No, it is evident that present politicians & CEOs are mostly pig-ignorant regarding the importance of old forest. They must be ousted or educated and held to sustainable policies on the issue of forest energy.
Personally, defeatism on this issue is not an option that I'll countenance.
7/. Will new coppices be just monocultures of foreign species on a minimum harvest cycle ?
No, this would be very unwise, given the propensity of monocultures to attract disease and ruinous pest invasions, and the climatic instability that means the shorter the harvest cycle the less reliable the tonnage harvested - which could be really embarrassing for those with investment in the local processing plant.
Notably, mixed native species coppice that is "in cycle of over 9yrs" (i.e. where part is still harvested each year) is not only around 20% more productive than normal woodland with the same species, it also holds the highest biodiversity of any European ecosystem.
Also, the oldest coppice tree yet found in the UK is a Hazel near Ashford in Kent, that must have been cut hundreds of times, because it was planted during the Roman occupation of Britain, around 300 AD.
8/. Doesn't burning trees release air pollution ?
As I guess all readers here may know, woodland inhales CO2 as its trees grow, and exhales CO2 & CH4 (methane) as they die and rot or burn.
An efficient wood-energy plant will not release any more CO2 than essential, as the carbon is a valuable potential energy resource. What little is unavoidably released will be a small part of what the coppice growth takes in. No other hydrocarbons should be released.
A wide range of hydrocarbon gasses and vapours are produced by pyrolyzing wood (kilning without ehough oxygen to bun) and these allow various products, including charcoal for Terra Preta, Syngas for cooking or power production or, perhaps best of all, as feedstock for the liquid fuel Methanol (CH3OH).
The latter can be produced at over 60% conversion (by weight) which implies around 100gls (petrol equivalent) per tonne of fuelwood processed.
Finally, to put woodsmoke to its very best use of all, it's worth filleting some fresh trout and cook-smoking them over oak twigs. They are lovely beyond words !
Regards,
Lewis C
Six of one, half a dozen of another: there is no significant difference between the amount of carbon released whether the wood rots on the forest floor or goes up a chimney. On the earth's 'surface', there is a cycle - living trees soak up CO2, dying (or burning) wood releases it.
On the other hand, the combustion of fossil fuels (oil, coal and gas) releases into the air ancient carbon - which had been buried deep below the earth's surface - thereby increasing the atmospheric concentration of CO2.
Sounds good on paper, but there's not as much energy in wood as there is in Coal.