Natural gas is not better for the climate than coal. The problem is, it leaks when they drill, and more so with horizontal drilling and fracking. The drilling process has always included some venting at the beginning of drilling. In addition, processing and transporting gas involves leaks; most of the pipe system for natural gas is over 50 years old.
The reason why people why people have referred to natural gas as a clean fuel is that burning it emits half as much carbon dioxide (CO2) as coal, and also less soot and smog.
However, natural gas is nearly all methane, a much more potent warming gas than carbon dioxide. For the first twenty years after methane is released into air, it has a warming effect 110 times as strong as carbon dioxide, according to newer studies. Then methane gradually breaks down, and its warming effect, measured over a 100 year period, is about 25 times as strong as that of carbon dioxide.
That is one reason why there are burning flares on oil fields. Natural gas often comes out when they drill for oil, and they burn it. Then it releases carbon dioxide instead of the more potent gas, methane.
So how much methane escapes when they retrieve and process natural gas? Estimates of leakage and venting rates range from 1.5% to 8% of the gas retrieved. It is very difficult to measure this, and it has not been regularly done.
Counting only emissions from burning, not from leakage, natural gas releases 117 pounds of CO2 for each million BTU of energy output, diesel oil releases 161, and coal releases 210 pounds, according to the EIA.
If we assume a low leakage rate, say 3%, of the natural gas, and then take the lower warming multiple of natural gas/methane, of 25, and add that CO2 equivalent to the 117 pound of CO2 emitted by burning, we see that the total use of natural gas releases the equivalent of 205 pounds of carbon dioxide, about the same as for coal. Assuming a higher leakage rate, like 5% and a higher warming multiple of say 75, gives natural gas a CO2 equivalent warming rate of 556 pounds, or two and a half times worse than coal.
The US government has been encouraging more production of natural gas in the US, referring to it as a clean fuel, even though the Environmental Protection Agency admits that there has not been good data on the amount of leakage. Analysis of the leakage issue by scientists at Cornell University has pointed out that this poses a serious danger to the climate.
The response of the government, and some industry representatives and environmentalists, has been to call for regulations controlling leakage. It is hard to imagine that venting and leakage could be reduced much below 3%, especially since they have been a regular part of the retrieval process, and the cost of capturing those small amounts is greater than the gas is worth. Even if some companies in the US were able to reduce leakage, that is not likely to be done in drilling in other countries.
Most of the natural gas in the US is used for heating buildings and for generating electricity. Geothermal technology is an excellent clean alternative for heating and cooling buildings. Wind energy can provide electricity at rates that are competitive with electricity generated by natural gas. We have affordable and safe alternatives to natural gas.
A few years ago, decision makers made a serious mistake in promoting ethanol, although studies show that its greenhouse gas emissions are as bad as oil.
The world is too close to catastrophic effects of global warming. New investment in electricity generation should only be in green technology now, replacing natural gas and coal generation facilities as they reach the end of their life spans.