The two biggest hitters causing global warming are electrical generation using fossil fuels and transportation using fossil fuels. If we made all electricity carbon neutral, most of which would come from wind and solar generation, that would be about a third of the problem. If we made all vehicles run off of carbon-neutral electricity (or biofuels where electricity just won’t cut it, an increasingly small niche), that would deal with another third of the problem or so.

This action would have a huge impact on global warming targets. Could we do it in 20 years globally in a crash plan? Let’s start with what it looks like today, or at least in 2016 per the IEA. Globally, we generated about 25,000 TWH of electricity (reminder on units: KWH, MWH, GWH then TWH, each 1000 of the previous unit).

A lot of that electricity comes from coal, gas and oil today, roughly 65% or in the order of 16,250 TWH.

Could we replace 16,250 TWH of electrical generation with wind and solar in 20 years? Well, it’s not actually that hard to generate a TWH of electricity.

A single 2.5 MWH wind turbine running for a year with a mediocre capacity factor of 35% will generate 7,665 MWH. To get a TWH, you’d need 130 of them, a reasonably sized wind farm of 325 MW capacity. For context, the Gansu Wind Farm in China is already at 8,000 MW capacity and is expected to reach 20,000 MW capacity by 2020, 60 times larger.

A solar farm is a bit different and has a typically lower capacity factor. Let’s go with a middling 20%. To get a TWH you’d need a solar farm with a capacity of around 570 MW. For context, a couple of solar farms in India are 1,000 MW and 2,000 MW capacity 2-4 times the capacity.

We can build a lot of wind and solar capacity quickly. The permitting is relatively straightforward, both are the cheapest new forms of generation in the world, and both are completely available to every country in the world (unlike nuclear). A new wind farm can be generating at least some electricity in about two years from conceptualization and a solar farm could be generating some electricity in a year.

So let’s suppose we wanted to eliminate most fossil fuel generation globally just for the electricity we are producing today, perhaps 8,000 TWH of wind and 8,000 TWH of solar. What would that look like? Well, that’s about 400 TWH from each a year. For wind that would be about 130,000 MW (130 GW) of capacity. That’s only 6.5 times more than will exist in a single wind farm by the end of next year in China. For solar, the number is bigger, about 230,000 MW (230 GW) of capacity.

How does that compare to last year’s renewables deployment? About 60 GW of wind generation capacity was installed in 2018, roughly half of what would be required. Solar achieved 104 GW of new capacity in 2018, also about half of what’s required for that form of generation to displace its share of fossil fuels in 20 years.

But of course demand is rising, on average about 3% a year, compounded. So in 20 years we’d need about 19,000 TWH more to cover increases in demand, assuming a flat line increase. Given the interesting trend of vastly increased efficiency and most of the new generation coming from China and India, which will level out soon enough, this is probably pessimistic.

However, let’s factor in every car in the world, all one billion of them, becoming electric in the same time frame. Cars globally drive around 16,000 kilometers in a year, more in the USA, less in most other countries. Electric cars take about 20 KWH to travel 100 kilometers. The math suggests we’d need around 3,200 TWH for just cars in 20 years, so we will leave the 19,000 TWH alone.

I rounded down last time, so I’ll round up this time and suggest another 10,000 TWH of annual generation each from wind and solar in 20 years. That’s 500 TWH per year. For wind generation, that’s about 160 GW of capacity each year. For solar, about 280 GW of capacity.

So if we wanted to electrify everything and account for demand growth and electric cars, we’d need to put in about 290 GW of wind and 510 GW of solar a year. We already have over a TW of wind and solar globally. The amount we put in last year was 20% of the amount needed for a total global replacement of fossil fuels and full expansion of demand to cover electrification of transportation.

That sounds pretty doable, especially as wind and solar keep dropping in price and coal and gas plants keep aging and needing to be replaced anyway. A lot of this is just going to happen organically.

Of course, there are still a lot of industrial processes that directly use fossil fuels for heat, CO2 production, and similar things. Solving two-thirds of the problem is excellent, but a great deal of work is required for the other third of the challenge as well. And of course there will be other forms of carbon-neutral energy coming on line in lesser amounts, including new nuclear (mostly in China), hydroelectric, geothermal, biomass and a smattering of tidal.

As for the 20-year time frame to replace gas and diesel cars with electric ones, 2018 was the first year when the number of internal combustion light vehicles sold in the biggest markets of China, Europe and the USA went down, ever. The number of cars still went up, but electric cars are now selling more than a million units in a year and rapidly increasing.

China is already at an 8% marketshare for plug-in electric cars, so growing that to the large majority of the market in 15 years or so is very viable. We are now entering the steep part of the S-curve of adoption.

The average car only lasts a dozen years or so. We’re not going to eliminate all internal combustion cars in 20 years. But it’s certainly possible to be only selling electric cars in 20 years, with many governments putting targets in the range from 2025 to 2040 as the drop dead date for selling gas and diesel vehicles. The youngest internal combustion car might be off the road completely by 2050.

This doesn’t address other forms of transportation including air travel, diesel-electric trains, freight shipping, and freight trucks, but those sectors have emerging or existing solutions which are not currently price competitive today. A serious price on carbon would suddenly make biofuels for air travel a lot more attractive, as one example. And multiple companies including Tesla and Volvo are driving toward electric freight trucks, among others. Even hydrogen might have a place in transportation at larger scales.

So yes, it’s very possible to make a huge dent in global warming in 20 years if the will existed. Ramping up renewable replacement of fossil fuels is viably scalable given the massive parallelization of deploying wind and solar and the proven scale of the industry today. Displacing internal combustion light vehicles is well under way and with multiple major markets committing to eliminate their sale within the 20-year window, all it would take was ratcheting up those targets.

Would this fix global warming? No. All that will do is slow the rate of warming given the amount locked in already, but that’s a big deal when every 0.5 degrees Celsius makes a huge difference. This next 20 years is crucial to how significant the impacts will be for the following 60 years.