Honey, I mitigated climate change

Actions of mankind release greenhouse gases into the atmosphere. Greenhouse gas concentrations have increased causing Earth to heat up, which has been evident during the last few decades. This global warming proceeds so fast that it causes problems for both the biosphere and mankind. These concerns have been largely noticed and the general attitude is that we will need to do something about the problem as soon as possible. There already are some limited efforts to do something about it. Although international policy decisions have not been forthcoming, there has been some action from different nations, corporations, citizen groups, and individual citizens.

The problem is largely in energy production, because for that we currently use mainly fossil fuels, which release a lot of greenhouse gases into the atmosphere when burned. We are therefore looking to replace fossil fuels with something that doesn't release so much greenhouse gases to the atmosphere. Examples of such energy production methods are wind power and solar power. These two are clearly good options. However, some of the options don't seem to be that good.

Natural gas and oil palms

Natural gas - issues with leaks and aerosols

There are a few fossil fuels which release different amounts of greenhouse gases to the atmosphere. One of these fossil fuels is natural gas, which releases clearly less greenhouse gases when burned than coal or oil. This is one of the reasons why there have been some efforts to increase natural gas usage. Unfortunately, looking merely at how much greenhouse gas is released when burned is a rather simplistic view. Lately it has been recognized that production of natural gas releases methane to the atmosphere through leaks from collection sites and transmission pipelines. This might negate the greenhouse gas benefits achieved during burning. If only a few percent of the natural gas leaks as methane into the atmosphere, then the natural gas usage has no greenhouse gas benefits at all compared to coal and oil. Some studies have reported much higher leaks than that.

From a climate perspective, there's also another problem with replacing coal with natural gas. Burning natural gas releases less aerosols to the atmosphere than coal. Aerosols have a cooling effect on the climate, so reducing aerosol emissions causes a warming effect. Therefore, replacing coal with natural gas has an additional warming effect (Hayhoe et al. 2002). This is a short-term effect, though, but the effect is timed so that it occurs just when we thought we would mitigate global warming by replacing coal with natural gas. However, we must remember that aerosols have harmful effects on human health, so reducing aerosol emissions may have some health benefits.

Bioenergy - issues with land-use

The basic bioenergy scheme hinges on the idea that we grow plants and then we burn them to get energy. Burning releases greenhouse gases, especially carbon dioxide, but we grow next batch of plants which take carbon dioxide from atmosphere while growing. The amount of carbon dioxide taken from atmosphere is the same as that which is released when burning the plants. So, idealistically this is a net zero emission energy. Emphasis here is strongly on the word "idealistically", because we know that this is not truly a net zero energy (although some people, even some researchers, still keep claiming that). First, biomass transportation and bioenergy production produces some greenhouse gas emissions which already make this a larger than net zero emission energy.

Second, during the last few years, the research on the subject has found out that the land use relating to bioenergy production produces huge greenhouse gas emissions when forests are somehow included in the bioenergy production scenario. The emissions from land use are large enough to initially produce similar or even larger emissions than fossil fuels. Emissions get smaller with time, but for many bioenergy production scenarios the emission cuts are not very large, even after a hundred years. For some scenarios, bioenergy greenhouse gas emissions are larger than that of fossil fuels, even after a hundred years. There are some scenarios where bioenergy can be a good option, though. Such a scenario is to grow bioenergy plants in degraded agricultural land.

However, instead of concentrating on good bioenergy scenarios, we cut down rainforests to clear land for oil palm plantations. We even burn the rainforests out of the way (Suyanto et al. 2004). We cut forests to replace them with maize fields to produce biofuels. In such cases the carbon storage, which the forest has sequestered into the soil, is released into the atmosphere. All of this results in huge carbon dioxide emissions.

Worst case scenario

What if we use lots of natural gas and forest-related bioenergy to replace coal and oil, and if the greenhouse gas emissions from natural gas and bioenergy are indeed as large as discussed above?

In such a case we would have replaced coal and oil with energy sources that have larger greenhouse gas emissions than coal and oil, at least in a 100-year window. But this is not yet the full story. We have replaced coal and oil with something we thought had less emissions, so we haven't done much else to reduce those greenhouse gas emissions. This means that not only have we increased our emissions, we have also lost potential emission reductions — twice as bad a situation as we thought we would have. The situation in real life might not be quite as bad as described here, but it may well be. Should we risk it?


Papers on gas leakage involving the natural gas industry

Papers on GHG emissions from bioenergy related land-use

Katharine Hayhoe, Haroon S. Kheshgi, Atul K. Jain, Donald J. Wuebbles, 2002, Substitution of Natural Gas for Coal: Climatic Effects of Utility Sector Emissions, Climatic Change, July 2002, Volume 54, Issue 1-2, pp 107-139, DOI: 10.1023/A:1015737505552. [abstract, full text]

Suyanto, S., G. Applegate, R. P. Permana, N. Khususiyah, and I. Kurniawan. 2004. The role of fire in changing land use and livelihoods in Riau-Sumatra. Ecology and Society 9(1): 15.. [abstract and full text]

Posted by Ari Jokimäki on Thursday, 27 March, 2014

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