If you follow my work at Our World in Data, you might have seen some of the recent work I did with my colleague Pablo Rosado on global biofuels. If you didn’t, this Substack gives a quick summary of the main points.
First, we ran a small thought experiment. The world currently uses around 32 million hectares of land for biofuels, roughly the size of Poland or Germany. Let’s imagine we wanted to keep using that land for energy production, but switch to another source. How much electricity could we generate if we put solar panels on it?
The numbers were quite staggering. So staggering in fact, that I doubted myself. I ran the calculations many times, convinced I’d accidentally added a zero somewhere. I asked Pablo to also come up with an estimate, without telling him how I got to my numbers. As it turns out, we took slightly different approaches, but landed somewhere similar. We wrote up all of our assumptions and methodology if you’re interested.
If we put solar panels on those 32 million hectares of biofuel land, we could generate around 32,000 terawatt-hours (TWh) of electricity. Incidentally, that’s the same amount of electricity as the world consumes in a year.
So we could keep the biofuels, which amount to around 1,400 TWh of energy, and meet around 4% of global transport demand. Or we could use it for solar and produce enough electricity to meet the world’s current electricity demand.
Of course, there are other things to consider when it comes to solar: energy storage, where these panels are built compared to where the electricity is needed. Our point is not that we should cover all of this land in solar panels, or that it would easily power the world on its own.
But this small thought experiment does make one thing clear: there are many, many more land-efficient ways to produce energy than growing biofuels.
We then ran a second thought experiment. Let’s say we specifically wanted to use that biofuel land to decarbonise transport. That is, after all, what most liquid biofuels are used for. How much of the world’s car and truck fleet could we power with solar on that land if they were all electrified?
The answer is all of them, and then some.
We estimated that based on current global mileage, an electrified car and truck fleet would consume around 7,000 TWh of electricity. Less than a quarter of how much of solar could be produced on biofuel land.
Again, we can use biofuels to meet 4% of transport demand, or we could use that land to power all road transport.
These comparisons all boil down to the efficiency benefits of solar over crops. Crops convert less than 1% of sunlight into biomass; solar panels convert around 20%. Add the efficiency gains of electrified cars over liquid fuels, and the efficiency gap widens further.
I’ve often wondered why biofuel land use doesn’t get the same public attention as solar or wind power. I think part of the reason is that many people don’t really think about agriculture as “land use”. Humans are encroaching on natural landscapes when they put metal and concrete down. That’s why sprawling cities, towns, and roads are seen as the big “human land use problem,” even though they only cover around 1% to 2% of habitable land. Agriculture makes up around 50%. But because it’s plants growing, it seems like a more natural part of the landscape.
The same applies to renewable energy technologies. Biofuels are just plants. Solar panels are big chunks of metal, concrete, and minerals.
You can read our full article on this here.
In another article, we looked at the numbers on aviation.
Here’s a brief summary of the main points.
Currently, less than 1% of the world’s biofuels are used for aviation. Almost all of it goes to road transport.
Those biojet fuels account for far less than 1% of global aviation demand.
If we took all of the world’s biofuels and allocated them all to aviation, it would meet a maximum of one-third of current demand (and probably quite a bit less once we take co-products and conversion losses into account). This comparison is in the chart below.
Waste cooking oils and fats get a lot of attention from aviation companies. If the world were able to collect all waste oils and fats, we estimate it could meet up to 4% of global flight demand. Not nothing, but waste oils won’t decarbonise the world’s planes.
You can read our full article on this here.
Again, none of the above is a specific policy proposal. We wanted to get a sense of perspective on the relative land use of different decarbonisation options. That can then be one input into the decisions that policymakers, investors, and others make about where to go next. If we were surprised by the numbers, I’m sure many others will be too.