Yeah that study is probably “true” but very myopic. I believe I commented on this the last time it was posted.
Sure, total co2/ch4 emissions is likely higher. Liquefying and transporting LNG isn’t energy free, while coal is typically burned closer to where it’s mined. I get that’s probably the tact they’re trying to take, fossil fuel still bad and don’t let LNG get too greenwashed.
HOWEVER. The study and article seems to intentionally completely ignore all the secondary emissions of coal. Tallying “emissions” for a picture of true environmental impact is way way way more than just X tons of co2. Burned coal creates a massive amount of atmospheric ash and particulate that is chock full of heavy metals, literal radioactivity, and sulfur/nox that generates acid rain. The tailings from mining and the fly ash from burning is also incredibly toxic and destroys all groundwater for miles and miles around it. It’s just one huge bad flaming lump of cancer that sanitizes entire ecosystems and reduces life expectancy by multiple decades in places where it is heavily used.
Natural gas generates none of this, with the exception of fracking groundwater problems (which, is admittedly a problem, but still way less concentrated than the previously mentioned). A fuel stock of >95% CH4 with the remainder made up of water and longer chain hydrocarbons emits nothing but CO2 and water vapor. Also, combined cycle gas power plants have some of the highest end to end thermal efficiencies of any power plant ever built, which is another huge plus over coal.
So no, it’s not perfect, and its still “bad”. but it is doing a fucking bang good job of not giving people cancer and getting a dirty 18th century energy source out of our modern society where it does not belong.
surely this would been known beforehand?
The article compares coal and natural gas based on thermal energy and does not take into account the greater efficiency of natural-gas power plants. According to Yale the efficiency of a coal power plant is 32% and that of a natural gas power plant is 44%. This means that to generate the same amount of electricity, you need 38% more thermal energy from coal than you would from natural gas. I’m surprised that the author neglects this given his focus on performing a full lifecycle assessment.
Natural gas becomes approximately equal to coal after efficiency is corrected for, using the author’s GWP20 approach. GWP20 means that the effect of global warming is calculated for a 20 year timescale. The author argues that this is the appropriate timescale to use, but he also presents data for the more conventional GWP100 approach, and when this data is adjusted for efficiency, coal is about 25% worse than natural gas.
I’m not an expert so I can’t speak authoritatively about GWP20 vs GWP100 but I suspect GWP100 is more appropriate in this case. Carbon dioxide is a stable gas but methane degrades fairly quickly. Its lifetime in the atmosphere is (approximately 10 years)[https://en.wikipedia.org/wiki/Atmospheric_methane#Mean_lifespan]. This means that while a molecule of carbon dioxide can keep trapping heat forever, a molecule of methane will trap only a finite amount of heat. This effect is underestimated using GWP20.
combined cycle gas powerplants can get almost to 60%
Unfortunately everything has byproducts and emissions that we do. The only real solution is to reduce, which is difficult given the population and so many third world nations wanting to join a higher standard of living. Natural gas is probably better than coal overall, but on the scale of bad for the environment where 10 is the worst, is an 8 or 9 better? Technically, yes.
Then nuclear is your option, not the option that permanently destroys water tables for billions.
I believe the biggest source of emissions for nuclear actually come from the construction phase, so getting past that, maybe. Still would be preferable to also reduce energy use so that the “better” source can be spread more efficiently.
