"I really wish that articles like this would give more context for all the numbers that inevitably get thrown around.
> China Huaneng Group Corp.’s 845-megawatt power plant
What percent of the city's electricity is that?"
Humanity uses about 17 terawatts of generated power (electricity plus transportation plus …), about 15 from fossil fuels, of which coal generates more GHG that all but the dirtiest oil and the leakiest NG facilities. That plant is probably used about 80% of the time, so it represents about 675/17,000,000 of humanity's power use and something like twice that much of our GHG generation.
We think we can generate about 500GT CO2e of GHG net before reaching 3°C warming (but that involves a lot of guesses), which is a level that seems civilization-destablizing to many observers (wild, but necessary guesses). Coal creates about 1kg per kWh, so convert from 675MW … 60sec60min24h365d675,000kW = 21,286,800,000,000 kg/yr, or ~21GT/yr, or 4% of that budget.
Coal has an energy density of about (depending on type) 24 MJ/kg, which is a shade under 7 kWh per kg, so your final number is off by a factor of 7 or so [EDIT: I think? Or you're saying that coal creates 1 kg CO2 per kWh? Ok... Yeah, I think that's right!]
The 500GT budget is total. That plant is using roughly 4% of our let's-not-wildly-destabilize-civilization GHG budget every year. We've got about 30 years to radically restructure our energy use. More here (among many places): http://www.ipcc.ch/report/ar5/syr/
Are you sure this is right? There must exist more than 25 coal plants in the world? Do we expect to hit this budget w/in a year? Is this coal plant much bigger than most others?
There are a lot more than 25 coal plants in the world, and we must stop using them very very soon. Here's an EPA-citing source claiming 1 Gt coal -> 1.8 Gt CO2e, and 3.5 Gt used by China in 2011, the latter amounting to ~6.5 Gt CO2e, and ~20% of world emissions that year. [1] If Chinese coal use is now about the same, and if we have 650 Gt left before some particular nasty tipping point is reached, then China's coal is currently using that budget at a rate of 1% a year. There's a lot of uncertainty in the rate measurements, and significant uncertainty in the tipping points, but there is no uncertainty that world will be like nothing humanity has ever seen at 500ppm CO2, and we have no reason to think that, say, Pakistan, India and Bangladesh can adjust smoothly to regular high temperatures of 54° with sporadic heat waves at 57°, or that America and the US can smoothly adjust to most of the farmland that currently feeds them becoming unusable and most of the fisheries collapsing.
Finally, note that we're not going to get to near carbon-neutrality in 30 years by dropping radically next year, continuing at a flat 1/30th of our budget for 30 years, and then dropping to 0. Any plausible route will accelerate GHG reductions something like linearly.
Ok, thanks for the info, now I have a better sense of proportion. So that means that 25 years brings it to 1% globally. I see how breaking the cap might not be totally inevitable but it doesn't seem very evitable either. I think we could see a major food price increase in our lifetimes.
China has very dirty coal compared to the US. We also have much better environmental tech installed for our plans, while in China they don't bother since enforcement of environmental laws are weak.
Humanity uses about 17 terawatts of generated power (electricity plus transportation plus …), about 15 from fossil fuels, of which coal generates more GHG that all but the dirtiest oil and the leakiest NG facilities. That plant is probably used about 80% of the time, so it represents about 675/17,000,000 of humanity's power use and something like twice that much of our GHG generation.
We think we can generate about 500GT CO2e of GHG net before reaching 3°C warming (but that involves a lot of guesses), which is a level that seems civilization-destablizing to many observers (wild, but necessary guesses). Coal creates about 1kg per kWh, so convert from 675MW … 60sec60min24h365d675,000kW = 21,286,800,000,000 kg/yr, or ~21GT/yr, or 4% of that budget.