Coal is going away. What will it take to replace all of the things it provides us with? An infinite number of wind turbines would be required to replace everything a coal plant gives us.
If it was just the electricity, only 120 to 350 modern wind turbines would be required, but that’s just the start.
These are averages and capacity factor-based. It’s an approximation. Capacity factor is the percentage of a year’s potential maximum generation that is actually achieved. If a generation unit could generate 100 MWh but actually generates 70 MWh — that’s a capacity factor of 70%. It’s based on a demand, market conditions, supply, maintenance, and the like.
As coal plants are shutting down, they’ve also been dropping in capacity factor, and now have an average of under 50%. We’ll use 50% as our capacity factor for coal.
In 2016, there were 381 coal plants with just under 800 generating units. The average coal plant was running around 720 MW of capacity. We’ll use 720 MW of capacity for coal as the basis.
720 MW of capacity running 24/7/365 with a capacity factor of 50% would generate about 3.15 TWh of electricity in a year.
The average capacity factor for modern wind turbines in the US is 41.9%. The average size of new wind turbines in the USA is 2.43 MW in capacity.
The first question is how many wind turbines would be required to generated 3.15 TWh of electricity.
3.15 TWh divided by 2.43 MW capacity divided by 24 hours divided by 365 days divided by a capacity factor of 41.9% gives us about 353 wind turbines.
So the first answer is that just over 350 wind turbines are required to replace a coal generation plant which likely has 2–3 generating units. That means that about 120–175 wind turbines are required to replace a single generating unit.
So far, so good. But coal plants do more than provide electricity. What else do they provide, and can wind turbines provide that too?
Let’s start with CO2, the primary greenhouse gas. Coal generation produces about a ton of CO2 per MWh of generation. That means that the 3.15 TWh of generated electricity from coal produced over 3 megatons of CO2.
Wind energy doesn’t generate any CO2 from operation, but the full lifecycle of materials, manufacturing, distribution, construction, operations, and decommissioning does currently have a CO2 debt that must be divided by generated electricity. Lifecycle cost analyses shows that wind turbines produce 5–8.2 kg of CO2e per MWh. That’s 0.5% to 0.82% of the CO2 per MWh of coal.
That suggests that to get the same CO2, we’d have to have 43,000 to 71,000 wind turbines.
Using the same generation calculation, in order to get the same CO2 as from the coal, the wind turbines would generate 385–631 TWh.
Gee, that kind of sucks, doesn’t it? So many wind turbines to create the same things coal does! But wait, there’s more.
Coal generation also produces 84 kg of coal ash per MWh, so that coal plant produces about 265,000 tons of it a year. Wind generation doesn’t produce any coal ash, or indeed anything like it, so an infinite number of wind turbines would be required.
Coal generation also produces about 2.4 kg of sulphur dioxide, a nasty air pollutant, per MWh, so that coal plant produces about 7,540 tons per year. Wind generation doesn’t produce any sulphur dioxide, so yet again, an infinite number of wind turbines would be required.
Coal generation also produces just under a kilogram of nitrous oxide, another nasty air pollutant, per MWh, so about 3,000 tons of that per year. Another infinite number of wind turbines required.
Coal generation also produces about 0.1 kg of particulate matter per MWh, so that’s another 315 tons of PM2.5 and PM10 particulates that clog lungs. Once again, an infinite number of wind turbines are required.
Oh, wait, there’s more! Coal emits about 13 milligrams of mercury, a toxic heavy metal and bioaccumulator that causes insanity and organ failure, per MWh. That means that coal plant is pumping about 41 kg of mercury into the air every year too! Sadly, yet another case where wind turbines don’t emit any mercury, so another infinite number of them required. Coal generation produces half of all mercury emissions annually, so that’s a big loss.
Finally, there’s background radiation. The majority of radiation from human sources that the average person is exposed to is from coal emissions as carbon-rich dirt with trace radioactive elements is burned. Once again, zero radiation from wind turbines, so an infinite number required.
All that nets out to about 78 deaths due to air pollution and accidents from that one coal plant per year as the rate is estimated at 24.6 deaths per TWh. Meanwhile, wind energy has about 0.04 deaths per TWh, 615 times fewer. Once again, coal is clearly the leader by this metric. That means it would take about 217,000 wind turbines to kill as many people per year.
Really, it’s amazing that anyone can consider replacing coal with wind energy when you look at how many wind turbines it takes to replace the things we get for free from coal.
Obligatory Poe’s Law warning.