Posted by: Dave Neads | February 7, 2008

Burning Trees and Global Warming

I’ve been receiving a lot of mail wanting to know more on this issue.  I have prepared a backgrounder.  It is rather long, but I think it covers the bases.  If you want to know more… be informed…read on…


Burning Trees is not “Clean Energy”

The Premier’s energy strategy puts a lot of emphasis on trees as carbon sinks and sources of “clean” energy. The claim that trees are carbon sinks is true; however, the claim that burning beetle-killed forests to create electricity is “clean and carbon neutral” is entirely false. In fact, burning beetle-killed forests actually increases greenhouse gas emissions, front loading the system hugely. (see appendix one)

On the land side, the removal of forests to burn for electricity diminishes soil capability by removing nutrients and it also removes habitat for a myriad of biological processes vital to soil maintenance and health. There is no such thing as waste; the forest uses it all. The increased rate of logging necessitates more roads, more fragmentation and more clear cutting, destroying more habitat. (see appendix two)

The economics of burning forests to create electricity will require a huge increase in rates to pay for the logging and transport costs of getting the trees to the burner as well as the capital cost of construction. Current proposals will need to receive at least 10 cents a KW to be viable, much more than the current rates B.C Hydro pays. (see appendix three)

The way the new Bio Energy Plan is structured there is no opportunity to participate in global carbon trading because none of the proposals are incremental to existing operations.
(see appendix four)

The technologies which may be available to deal with CO2, NOx and other harmful emissions are not fully developed and are expensive to install and operate. (see appendix five)

Taken together, these elements show clearly that burning forests is in direct conflict with current policy direction of reducing greenhouse gas emissions and further, such a policy will create more environmental and economic problems than it solves.

For these reasons, the current policy needs to be revamped, removing the burning of beetle-killed forests as an option for electrical generation.

Appendix One

CO2 Release

The average age of trees in the interior ranges from 100 to 250 years old. When you burn that tree, the CO2 emissions released into the atmosphere will take the same length of time to be reabsorbed by new growth.

It is true that young trees pull carbon out of the air at a faster rate than older, more mature trees. However, the issue is the volume of carbon sequestered, not the rate. If X amount of carbon is released during the burning of a 150 year old tree it will take the next 150 years to remove an equivalent amount of carbon from the air. There is no free lunch.

Intensive silviculture will shorten the time frame somewhat, but even in so-called managed stands, the time to reach the same size tree will be 80 or more years. So the idea that managed stands will solve the problem is not true. The other issue with managed stands is who will pay for the increased cost of thinning, fertilizing, stand tending and the entries required to do the work? Currently, there would have to be large government subsidies to carry out such programs. The companies cannot afford it.

Yes, the trees will rot. How fast and how completely is not fixed, but the parameters are anywhere from 20 to 40 years for a tree to decompose on the ground. It is a mistake to think of the same carbon release as burning because, as the tree is eaten by the microorganisms, plants, and small animals, much carbon is directly taken into the soil by chemical and biological means. So not only does rotting not release as much carbon, it does so at a rate 20 to 30 times more slowly than burning does.

Finally, what is true for CO2 emissions is also true for Methane, a much more potent greenhouse gas, and Nitrous Oxides, which are very harmful to health.

Appendix Two

Soils

As the trees disintegrate into the ground, they provide habitat for a huge range of biodiversity. In fact the vast majority of diversity in the forest is to be found in insects, invertebrates and other smaller life forms. It is this diversity which keeps soils enriched, productive and healthy. The removal of the trees for burning takes away much needed nutrients for the life process in the soil and the elements which give capability to the soils to produce new forests.

A personal communication from Dr. Bill Chapman says it all:

“Some carbon in all systems ends up as recalcitrant compounds
in the soil, with very long residence times indeed–in the hundreds of
years. Another way to look at the problem, rather than focusing on
rates of decomposition is to look at the volume of wood in various
stages of decay that are present in a steady state forest (one that is
neither accumulating or losing wood volume over a rotation). Typically
there may be at least a volume of wood on the ground that is equal to
the standing volume of timber in the forest (though this varies
considerably). In other words, it would not be uncommon to have carbon
storage equal to another entire standing forest in the form of woody
debris. The wood on the ground in a mature forest is in a steady state
of flux, i.e. the rate of breakdown is equal to the rate of recruitment
and recruitment comes during major disturbance, MPB attack or fire, and
minor ongoing disturbance (e.g. various types of self thinning). If the
woody material that is an integral part of our forest is going to be
used for power generation then you can see that another entire forests
volume of wood (roughly) will now be suspended as CO2.

Another issue in this that has been conspicuously overlooked is that
rotting wood plays an integral part of forest function. There are
energetically two halves to a forest. There are the organisms that fix
carbon (plants and a few others) and those that use the fixed carbon-
e.g. animals insects, fungi, etc. One of the largest repositories of
energy in the forest is wood and if that wood is taken away, you are
essentially removing 1/3 or more of all the biological activity in a
forest. Because much of that activity is conducted by smaller
organisms, e.g. ants, fungi, bacteria, mites, nematodes, etc., we tend
not to think about it. However, the vast majority of the biodiversity
in our forests resides in the soil and is powered by detritus, including
to a very large extent woody inputs. Logging already removes
significant amounts of wood and if we are going to burn even more, this
is nothing short of mining our forests. By condoning this, we are saying
a. that we don’t care if many if not most of the organisms that make up a
forest disappear due to lack of food, and b. we think that there won’t
be any consequences to forest management from eliminating those organisms.

Point b. is particularly important. Those organisms that live off
detritus have very important roles. They are the organisms that create
diversity in the forest and as such are the foundation of those two very
trendy characteristics- resilience and stability. As people learned
thousands of years ago in agriculture, the most fundamental step in
managing soil is to manage organic matter. If you don’t, the result is
declining fertility, reduced moisture holding capacity, reduced nutrient
holding capacity, declines in the physical condition of the soil,
increased insect and disease attack, etc. This is why organic matter
management is the keystone of organic farming- but it is also essential
in normal farming.

The very same principles apply in forest management, it is just that the
forms of organic matter are different and so forestry managers have been
slow to see the links. In forests, the organic matter often accumulates
in forest floor and rotting logs rather than being intimately mixed with
the mineral soil. Nevertheless, forest floor, including rotting logs,
are used preferentially as rooting media. Yet there seems to be a blind
acceptance that the forest will be unaffected by the loss of some or all
of these attributes.”

Appendix Three

Economics

It costs money to get the trees to the site of the bio-fuel facility. In the short term that is subsidized by the saw log component of the forests being logged. As the pine beetle continues to change the forest structure, the quality and percentage of saw logs in the cut blocks goes down. Finally a point is reached where the whole logging operation is just to get wood to the burner.

Typically, in the interior right now the cost of getting logs to the mill is about $30 a cubic metre, although this may vary widely from area to area.

The point is that the cost of getting the wood that ends up as sawdust, bark and other fuels to the mill is paid for by the saw log production. If wood has to be brought to the mill solely for purposes of burning for electricity, then the cost of generation rise sharply.

To protect the viability of the plant, the selling price of power to B.C Hydro has to be high enough to make the logging of trees for burning possible. One proposal on the table right now needs B.C Hydro to pay $1.00 a MW hr to make the project feasible. This is considerably higher than other alternative sources such as Run of the River.

Banks require at least 20-year licences to secure the investment. The Ministry of Forests is reluctant to issue such licences right now because there is no way to know just how long the supply of beetle killed trees will last.

Appendix Four

Carbon Trading

For carbon credits to be issued, the action must be incremental to what would normally be done. In the case of logging beetle wood, there is an obligation already on the books to ensure adequate regrowth over time. So the claim that planting trees is introducing a new carbon sink is true only if these new trees are being planted above and beyond the areas being logged.

As pointed out in appendix one, simply planting trees to replaced logged ones is not incremental to the system and in no way makes up for the carbon release when old trees are cut down and burned.

As Vaughn Palmer points out in his Vancouver Sun column of Thursday January 31, 2008

“Tree planting doesn’t reduce reliance on fossil fuels. It doesn’t lead to changes in energy production, transportation, industry, home heating, and other sources of emissions. It may not even sequester carbon in any permanent fashion.
Mark Jaccard, the Premier’s technical adviser on the climate action plan, framed the concern about reforestation as follows in a recent speech to the C.D. Howe Institute:
‘Was the planted tree truly an additional investment in reducing greenhouse gases or would another tree have sprouted eventually in that spot anyway?
‘Does the planted tree represent a permanent increase in biosphere sequestration or carbon or will it be cut down in 10 years’ time?’ ”
These and many other questions must be answered before any credible organization will recognize tree planting as a carbon credit. In the end the best carbon credit is to leave the tree standing, let it rot and let the new forest emerge.
Carbon credits issued for not logging would be appropriate and defensible when weighed against the releases of logging and burning.

Appendix Five

Technologies

In the past the way wood was burned was fairly straightforward. It was mixed, at high temperatures with oxygen, burned in a turbine, steam was created and that was used to generate electricity.

Nowadays there are new processes such as gasification available which are more complicated, but which have the potential to be cleaner, not just from a particulate point of view, but from a greenhouse gas emission perspective as well.

The problem, though, is that the complicated processes cost a lot of money and are not yet 100 percent efficient. Even if implemented, then you have a disposal problem for pollutants washed out of the process.

Gasification heats wood pieces to a high temperature in a closed chamber. When the proper temperature (several hundred degrees C) is reached a small amount of oxygen is introduced which causes a pyrolization of the wood, creating a synthetic gas, called syngas. A small amount of ash remains which then is disposed of.

Syngas is composed of hydrogen, carbon monoxide, carbon dioxide, and methane as well a nitrogen. To be environmentally friendly, the syngas components can be separated out, and used for other industrial process, leaving Hydrogen as the fuel for combustion. This would be ideal, but it is a complicated costly process and largely still experimental, and on top of tha, syngas is typically only 20 to 25 percent hydrogen.

The proposals that are on the table at the moment simply burn the syngas in a turbine to generate the electricity. While more efficient than creating steam, syngas is not as energy rich as raw wood or coal or fossil fuels. In fact, you need three to six times as much syngas per unit of energy produced compared to fossil fuel consumption. In the end this means more trees into the burner to get the energy out.

An example to illustrate:

There is a proposal in Anahim Lake to burn 150,000 cubic metres of wood to make 10 KW of electricity. It will get us off 3.5 million litres of diesel burned each year and save over a million dollars in fuel costs.

3.5 million litres of diesel, when burned, produces about 10,00 tonnes of CO2. 150,000 cubic metres when burned at a rate of 80 percent efficiency releases 15,000 tonnes of CO2, a 50% increase over diesel.

The lesson here is: be careful. Carbon is carbon, oxidization is oxidization, no matter how you couch it.

So, only if the CO, the CO2, the methane and the nitrogen are removed from the syngas before it is burned, can you reduce the green house gas emissions by going from diesel to wood.


Responses

  1. If you really want to get a sense of what might happen when trees become the equivalent of the corn / ethanol bubble, look no further than Nova Scotia. A US company, Neenah Paper, is allowing its lands to be clearcutt for fuel.

    While Canadian environmental groups are fighting for legislation to stop this practice, corporations are useing “carbon neutral” green speak to fatten their wallets.

    http://halifax.mediacoop.ca/story/2241


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