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Researchers contend that large-scale forest bioenergy is neither sustainable nor greenhouse-gas neutral (updated with link to full study)

21 April 2012

Schulze
Land management trade-off: maximizing productivity vs. carbon stocks. NPP= net primary production. Schulze et al. Click to enlarge.

Large-scale bioenergy production from forest biomass is unsustainable and will increase greenhouse gas emissions, according to a group of international researchers in an invited analysis in the journal Global Change Biology/Bioenergy.

Some 60-70% of the global increment of woody biomass would be needed to produce 20% of current global primary energy supply, they note, and argue that such an increase in biomass harvest would result in shorter rotations, younger forests, lower biomass pools, depleted soil nutrient stocks and a loss of other ecosystem functions.

Depleted soil fertility requires fertilization that would increase GHG emissions, and deterioration of current biomass pools requires decades to centuries to be paid back by fossil fuel substitution, if paid back at all, they contend.

Thus, early suggestions that a large-scale forest biofuel industry would be greenhouse-gas neutral or even reduce greenhouse emissions “are based on erroneous assumptions,” according to the authors from the Max-Planck Institute for Biogeochemistry in Germany, Oregon State University, and other universities in Switzerland, Austria and France. The work was supported by several agencies in Europe and the US Department of Energy.

The general assumption that bioenergy combustion is carbon-neutral is not valid because it ignores emissions due to decreasing standing biomass and contribution to the land-based carbon sink. The notion of carbon-neutrality is based on the assumption that CO2 emissions from bioenergy use are balanced by plant growth, but this reasoning makes a ‘baseline error’ by neglecting the plant growth and consequent C-sequestration that would occur in the absence of bioenergy production, and it ignores the fact that fossil fuels are needed for land management, harvest and bioenergy processing.

Recent life cycle assessments cast doubt on the existence of emission savings of bioenergy substitution from forests. In the Pacific Northwest United States, policies are being developed for broad-scale thinning of forests for bioenergy production, with the assumed added benefit of minimizing risk of crown fires. This includes forests of all ages and thus timeframes of biomass accumulation. However, a recent study suggests that more carbon would be harvested and emitted in fire risk reduction than would be emitted from fires. Furthermore, policies allow thinning of mesic forests with long fire return intervals, and removal of larger merchantable trees to make it economically feasible for industry to remove the smaller trees for bioenergy. These actions would lead to even larger GHG emissions beyond those of contemporary forest practices.

Increased GHG emissions from bioenergy use are mainly due to consumption of the current carbon pool and from a permanent reduction of the forest carbon stock resulting from increased biomass harvest. When consumption exceeds growth, today’s harvest is carbon that took decades to centuries to accumulate and results in a reduction of biomass compared to the current biomass pool.

—Schulze et al.

Among the concerns they detail are:

  • The general assumption that bioenergy is carbon-neutral is not valid.

  • The reduction of biomass and lost carbon sequestration by forests could take decades to centuries to be “paid back” by fossil fuel substitution, if paid back at all.

  • There are significant concerns about the economic viability of biofuels, which may require government mandates or subsidies.

  • A higher demand for biomass from forests will increase prices for the biomass, as in Germany where they have already increased in price 300-600 percent from 2005 to 2010.

  • An emphasis on bioenergy production from forests could lead to shorter rotation lengths, questionable management practices and increased dependence on wood imports.

  • Negative impacts on vegetation, soil fertility, water and ecosystem diversity are all possible.

  • Fertilizer use, another important source of greenhouse gas emissions, could increase.

  • The use of fossil fuels in the Industrial Revolution allowed previously degraded forests to recover in much of Europe and the US, while industrial-scale use of forests for biomass would likely reverse this trend.

If biofuels are desired, the researchers said, a better alternative would be to produce them on lands that once were forested but now are not, although that runs the risk of competing with food and animal forage production.

Society should fully quantify direct and indirect GHG emissions associated with energy alternatives and associated consequences prior to making policy commitments that have long-term effects on global forests. Reasonable alternatives for reducing GHG emissions on the order of the proposed bioenergy substitution include increased energy efficiency and reduced waste of energy via technological improvements and behaviour modification. There is a substantial risk of [sacrificing] forest integrity and sustainability for maintaining or even increasing energy production with no guarantee to mitigate climate change.

—Schulze et al.

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April 21, 2012 in Biomass, Biorefinery, Lifecycle analysis | Permalink | Comments (24) | TrackBack (0)

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Bio-fuel supporters will not believe it and continue to claim that we could run 5 B bio-fuel guzzlers forever.

Which feed stock is the worst for the environment, forest; corn/grains or sugar canes? Which one would be the most sustainable?

Harvey

We don't yet, but I have been waiting for this king of study for quite some. Clearly the picture is not rosy for biofuels at this point Their economical viability is questionable without subsidies, their environmental effect seems more negative than positive and their societal impact is also a problem. They should be strictly limited to marginal non agricultural lands.

Obviously we have to find out the right level at which to harvest a forest for sustainability, and if that includes fertilizers so be it.. but it has become clear we cant afford to keep a forest untouched, all must contribute in this human endeavor. Thank God vast reserves of NG are popping up everywhere. What about bio-char?

The forest is going to need the return of its minerals:  phosphorus, potash.  It may do better with retention of things which build soil, though this may only require low-growing cover plants until the trees are tall enough to shade out their competition.

What's left could be taken for fuels or materials.  There's a substantial amount of biomass not usable for saw logs and hard to use even for pulpwood:  bark, small limbs, leaves/needles.  If this can be compressed or otherwise processed for economical transport, it might not have an undue effect on sustainability.

"Thank God vast reserves of NG are popping up everywhere"

Thank God?? How on earth can you be so ignorant as to say that? There is no free energy, and the resulting climate change / ground water pollution resulting from this fracking orgy will haunt many generations long after you are dead and buried.

Since "....some 60-70% of the global increment of woody biomass would be needed to produce 20% of current global primary energy supply.....", it seems to me that if woody biomass is to be exploited on a commercial scale then it might make sense to reserve it for producing aviation fuels (i.e for burning in aero-engines), because this is an area where substituting hydrocarbon fuels with something else presents exceptional difficulties. As I recall, the energy use represented by the burning of fuels in aero engines represents only about 3% of global primary energy supply. My comment is subject to the condition that the energy requirements for converting the woody biomass into fuels usable in aero engines is equal to or less than the energy needed to obtain unit mass of fuel from conventional sources such as oil. Efforts in the aircraft and aero engine industries to reduce fuel consumption - per passenger-km in the case of people and per tonne-km in the case of freight - have been ongoing ever since commercial aviation first started. At least one successful series of flight tests that I know of has been carried out, involving the use of "bio-diesel" (derived from soybeans) in place of kerosene(derived from oil). I'm sure the production of aviation fuels based on woody biomass as opposed to conventional sources such as oil is at least worth serious investigation, if that isn't happening already.

Aviation? : solar powered neutral lift dirigibles, leave the expensive bio-gasoline for classic car clubs, for use on weekend rallies.

Anne dont dispair, CO2 is plant food, and global warming will speed up plant growth.

Good study. One essential issue I am missing for that story. Wood biomass processing or combustion shall be localized as much as possible. Transportation has major impact on sustainability since it is very low calorific value per cubic unit. In general auto transport distance should not exceed 50 miles or 150 miles by train for combustion purposes or distilation. Otherwise biofuel price goes up and sustainability goes down dramatically. That is major difference between biomass and oil, NG or nuclear stuff. Grain price is not so sensitive to transportation costs.

I don't understand why they even consider such a thing. We should be building LFTRs. Low cost, pollution free, inherently safe, nuclear power that can run off the world's vast supply of thorium for tens of thousands of years. No radio-active waste concerns either, and can slowly burn the waste we already have. See http://flibe-energy.com/attributes/

We aren't building LFTRs because the Clinch River lobby shut down MSR research and destroyed the knowledge base, and the anti-nukes destroyed the breeder reactor program in 1994.

Since the original journal article is not available for free online, I have to go by this article. The key line is "Some 60-70% of the global increment of woody biomass would be needed to produce 20% of current global primary energy supply." I'm assuming this means that the 60-70% figure refers to annual growth, not existing total tree biomass, and that the 20% figure is for all energy, not just portable transportation fuels.

However, biofuel development is primarily focused on portable transportation fuel, which would be a fraction of "global primary energy supply." Biofuel is not a major component of primary electricity production, where other sustainable technologies are more appropriate.

The shift to shorter rotation harvest is already happening in the forestry industry, especially for non-saw lumber production. For pulp wood, which would be the appropriate analogue to biomass production, short rotation has become the norm. Research on hybrid poplar has shown the ability to produce equivalent total biomass at 20 year full tree harvest to old growth 70+ year trees. As a forest matures, most trees have to die, since available nutrients can only support a fixed total biomass, whether that be a large number of small plants, or a small number of large ones. Those trees that die, oxidize (rot) and release their stored carbon.

Cellulose production, the primary feedstock for biofuels, is a low fertility demanding process for plants. Seed production from annual plants is what demands high fertility. Interplanting of nitrogen fixing alder bushes can provide sufficient fertility for short duration harvest cycles.

The assumption that biomass harvest would require fossil fuel use is unwarranted. Harvest machinery can use biofuel. Also the assumption that future demand would be equivalent to present demand is unrealistic. Fossil fuel production will go down and efficiency must increase across the board, irrespective of biofuels.A corollary would be the belief in 1820 that steam power would never replace the sailing ship since a steam engine can't carry enough fuel to be viable. This was true for the inefficient single-conversion engine, but within a few years the development of the triple-conversion engine was so efficient it marked the death-knell of the age of sail.

Linear transport should move to electrified rail, obviously. If automotive morphology were to keep pace with propulsion technology, the development of 100 mpg average fuel economy could become the new standard. If parallel plug-in hybrids were to become the norm, and two-thirds of miles driven were under stored electrical power, then the total need for portable transportation fuels, whether fossil or biofuel, would be a tiny fraction of the baseline scenario used for the study.


Anne dont dispair, CO2 is plant food, and global warming will speed up plant growth.

If only it were that simple;
http://www.skepticalscience.com/co2-is-plant-food-too-simple.html
http://www.youtube.com/watch?v=Er3iD5PIR00
http://www.skepticalscience.com/co2-plant-food.htm
http://www.youtube.com/watch?v=g093lhtpEFo

CREE has produced a very high efficiency white LED lamp with a 254 lm/W, that's 17 times less energy than incandescent lamps and almost 4 times less than CFLs. Used on all vehicles, homes, commerce. industries and outside lights, it could reduce e-energy consumption by as much as 10% to 15% and allow EVs to go a few more Km per charge.

Full study is available here http://bit.ly/HySkxu courtesy of OSU.
Mike

Look at the bright side. Maybe someone will dig so deep into one of the South American jungles that they'll drum up that ONE disease which will wipe out about 3/4 of the human race. A disease so virulent and toxic it solves the "human equation" in less than a decade.

THEN you'll see some REAL greenhouse gas reductions.

I know I'm crossing MY fingers!

sheckyvegas, nihilism of that level should begin with one's self.

Oh good another stupid study! This study is wrong on so many levels. Does anyone know how to do a proper LCA?

To start with, power plants are built one at time. For a given location does LCA show that reduced the environmental impact of an alternative way of doing something. For example, communities with saw mills used to have an air pollution until the waste was used to produce electricity. The 40 MWe biomass plant at Kettle Fall, Washington is a great example.

Forest health is major problem in the semi-arid forest of western North America. Year of well meaning forest fire management has resulted too much fuel resulting in fires that destroy the forest rather than rejuvenate the eco system. The first time a heavy rain comes along, the the soil and nutrients are washed into the surface water system already taxed to provide drinking water.

Putting a 25 MWe biomass plant about every fifty miles could mitigate the cost of cleaning the forest closets to where people live and use power.

Where I live not in Virginia, it is a jungle. Biomass waste is hauled to a landfill. Putting a 25 MWe biomass plant about every fifty miles could mitigate the cost and environmental impact of rotting biomass.

Just for the record nutrients are not lost. They can recovered from the ash.

The problem is the enormity of the engineering task of just increasing biomass by 2 % of the US mix is with these sources that would reduce the environmental impact compared to the present.

The study that looks at 20% is wrong because it is the first 2% that matters. Then we look at the next 2%.

You should elucidate on that.  I'd also elicit commentary on the suitability of pyrolysis oil for transportable fuel/feedstock.

I would say the best way to use biomass as energy is to use it in combination with other renewables. Solar and wind energy have a greater potential: America's electrical consumption could be fully met by a solar array only 100 miles square OR by wind turbines placed on just 2% of the land in just 4 states - if there was a way to store they generate for when the sun doesn't shine and the wind didn't blow.

OTOH biomass can be stored so let's stockpile it and use it to balance out the short term fluctuations in solar/wind.

http://www.solarserver.com/solarmagazin/anlagejanuar2008_e.html

I think the assumpton that biomass has to replace fossil fuels completely is a ridiculous farce. We throw away tons of this stuff every year, and there is really no reason it can't be converted to fuels. It may not be 20 million barrels a day, but why should it be. The argument goes like this: biomass may be economical, but because it will not power all our cars we cannot use it. Hogwash.

Biomass can supply enough material for plastics and such.  There appears to be enough to supply the liquid fuel needed for a fleet of mostly EVs and PHEVs.  But "happy motoring" in V8 SUVs... not gonna happen.

http://biophotovoltaics.wordpress.com/

Hydrogen is another neat way to store intermittent solar and wind energy and to store the very steady nuclear energy, if and when demands drop below production. Biomass is quite oxygenated in comparison to fossil fuel, which means that it can be hydrogenated into more energy-dense hydrocarbon. In the process, this addition of renewable-energy H2 allows a bigger market for hydrogen production AND together can increase the energy yield of combining biomass and hydrogen into liquid and gaseous hydrocarbon by 50-100% versus relying on biomass energy alone.

Agriculture will need fertilizer, and renewable-energy H2 can be used to produce ammonia instead of using NG right now in order to reduce GHG emission.

There are enough unemployments world-wide to start deploying renewable energy collectors and give jobs to the younger generation that is seeing YOUTH UNEMPLOYMENT LEVEL of 30-50% in Spain, Greek, Italy, South America, and may soon arrive to North America if the economic trend is continuing.

It is a total disconnect to see serious environmental degradation from the use of coal and GHG release from the accelerated use of NG and petroleum in order to save on labor and money, as commanded by the older generation, while the younger generation has no jobs, nothing to do and noting to look forward to...

Everything now is automated and computerized and outsourced! The mining and extraction of fossil fuels require little in the way of labor...unlike the more expensive and maintenance-intensive renewable energy collectors that can create local jobs...jobs that can't be outsourced.

Hydrogen is expensive and lossy enough that most storage uses batteries instead. Production of hydrogen is almost exclusively from steam-reforming of natural gas.

Long-distance transport of hydrogen is very lossy; it is nearly as viscous as methane but has about 1/3 of the energy per volume, forcing a much larger fraction of the embodied energy to be spent to move it.

If electricity is to be moved, wires are the most efficient way to move it. Hydrogen gas as a storage medium has merit, but direct electrolytic production of ammonia appears feasible and has far greater density and lower leakage.

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