Is natural gas better than coal

Study: natural gas is more harmful to the climate than coal

Actually, the race for the energy sources of the future seems already decided: If mankind wants to fight global warming successfully, it has to rely on energy sources that work with the power of the sun, wind, water or geothermal energy. Some climate researchers also include nuclear power in this climate-friendly quartet.

It is also certain that the share of fossil fuels such as coal and crude oil in the energy supply must fall drastically. So far, an exception has been natural gas, which many experts still consider comparatively climate-friendly because, compared to coal, only about half as much CO2 is produced when it is burned. In addition, natural gas is the perfect complement to support solar and wind power and is therefore repeatedly praised by the federal government as a "bridging technology" into the post-fossil age.

Energy companies like Shell or the Norwegians from Statoil also regularly stage themselves as climate protectors when they refer to their efforts to supply the world with natural gas.

But now a US professor is spoiling the story of clean natural gas. In the USA, the studies by Robert Howarth from the renowned Cornell University in New York State have been causing a stir for some time. Now that his latest study has been published in the journal Energy Science & Engineering (here as a PDF), the same could happen in Europe.

Howarth's central thesis: If you look at methane in addition to the greenhouse gas CO2, you will see that natural gas is a bigger driver of global warming than coal and crude oil.

The researcher published his results in 2011 for natural gas extracted from shale and sandstone by fracking. Back then, Howarth also admitted, there was a lack of reliable data sets. That has changed since then, he believes, and his current study is based on data published since 2011. In addition, there are now also considerations for conventional natural gas.

Methane beats CO2 The background is that methane is a 20 to 100 times more potent greenhouse gas than CO2. The values ​​fluctuate so strongly because methane only stays in the atmosphere for a comparatively short time. The longer the observation period, the better methane does in terms of the climate balance.

If one considers the short-term climate effects, even small amounts of methane that escape into the atmosphere can have at least as strong an impact on climate change as CO2. Means: the gas has so far been criminally underestimated in the discussion about climate change. Howarth also denounces this.

The methane is not produced during combustion (which produces CO2, among other things), but mainly during the extraction, transport and processing of natural gas. Experts speak of upstream and downstream here. Howarth also calculates the efficiency with which natural gas is burned compared to coal and oil.

Howard now assumes that between 1.7 and eight percent of the natural gas and thus the methane escape during extraction and transport. The result of his comparative calculation is shown in the following graphic:

For heat generation in the household (left) as well as for electricity production (right), crude oil and coal perform better than natural gas over a period of 20 years. The value in orange indicates the CO2 emissions during combustion. The red bar stands for the climate impact of methane (converted into CO2 values).

Criticism is programmed Howarth has been heavily criticized by researchers and industry representatives for his first study in 2011. This time, too, the critics will not be long in coming. Because despite the research on which Howarth relies, it is still a matter of dispute how much methane is emitted, especially when extracting natural gas. In addition, he sets the efficiency of new natural gas power plants around 20 percent too low and instead uses the values ​​of existing plants in the USA.

However, if his calculations turn out to be approximately correct, it will mean nothing less than an earthquake for global energy and climate policy. Suddenly coal would become socially acceptable again and there would no longer be a reason to shut it down in front of the natural gas power plants for climate protection reasons.

However, a lot of research is still needed for a final assessment, especially with measuring devices that reliably measure methane emissions on site. So it's time for the experts to finally tackle it. Howarth meanwhile draws his own conclusions from the results of his study: He wants to take all fossil fuels off the grid at once.

Update: Other researchers maintain that both shale gas and conventionally obtained natural gas produce only about half as many greenhouse gases as coal (here the study from April as PDF)

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