Can We Please Never Talk About Dedicated Biomass As A Source Of Electricity Again
Climate change is a complex topic. There are many questions on which reasonable people can disagree. It’s important to maintain a certain humility.
However, as the saying goes: “Don't be so open-minded that your brains fall out”. Sometimes there’s a reasonable-sounding idea, taken seriously by reasonable people, which turns out to not make sense.
For instance: fossil fuels are mostly decomposed plants. At some point, it occurred to someone that we could emulate nature and process fresh crops to create fuel. The result is a renewable fuel source – every year, we can plant another crop. Best of all, this doesn’t contribute to warming, because plants get their carbon straight from the atmosphere. Great idea, right?
Unfortunately not. I am here to say that growing crops to produce fuel for electricity is a ridiculous idea, and we should simply drop it. People talk about it as part of the climate solution, and they just shouldn’t. This emperor has no clothes.
(The analysis here is specific to electricity. I am also skeptical of growing crops for other energy purposes, but that will have to wait for another post.)
NOTE: as often on this blog, I’m summarizing a complex topic and attempting to give a straightforward conclusion. If I say something that seems oversimplified or straight-up wrong, let me know!
An Extremely Brief Introduction to Biofuels
People have been using plants for fuel since the discovery of fire. The technical term is “biomass”. This is just a fancy word for using wood, manure, or other plant material or animal waste to produce energy. Traditionally by burning it, of course, but the raw material can also be processed into a more concentrated fuel form, such as ethanol, before burning it.
Some biomass comes from waste materials (agricultural plant waste, lumber scraps, municipal waste, manure, etc.) Sometimes, crops are grown specifically with the intent of producing biomass for fuel. This is known as “dedicated biomass”.
Location, Location, Location
To power the move to renewable energy, we’re going to need a lot of land. How much land? We set out to investigate that, and I’ll be diving into the results in the next post. The figures are, if you’ll forgive me, all over the map:
For now, you just need to know that each box represents a source of electricity. The higher the box, the more land that source uses. You can see that the last box stands out above all the others: “BioDed” – dedicated biomass.
If you look carefully, you might notice that the vertical axis uses a log scale. You’d then be able to work out that, by these figures, dedicated biomass uses almost ten times as much land as the next source down.
However, that’s understating the case. That next source down, “Wind+”, represents land requirements for wind farms including all the empty space between the turbines. That space can often be used for other purposes (e.g. farming). If you consider just the space actually occupied by the wind turbines and their access roads, you get “Wind-”, way over on the lower left of the chart.
We pulled land usage figures from three different publications1. For each energy source, we pulled out the figure for LUIE (land-use intensity of energy), i.e. the amount of land required to produce a given amount of electricity. The most optimistic figure we found for dedicated biomass was 580 m²/MWh/y. The most pessimistic estimate for any other energy source2 was 23.5. So, using the figures that put dedicated biomass in the most favorable light, we find that it requires 25x more land than any other source of energy.
25 Times Worse, That’s Bad, Right?
Let’s run some numbers. According to Google, the world’s total arable land is about 1.38 billion hectares. Using the biomass LUIE figure of 580 m²/MWh/y, we get a total potential electricity production of 23,793 TWh / year. Based on the figures we came up with last time for electricity usage in 2050, this would probably meet 1/4 to 1/2 of the world’s requirements. In other words, if we devote the entire arable land area of the planet for biomass – no food crops, no forests, heck not even any cities in arable land – we still wouldn’t come anywhere close to meeting our needs for electricity alone.
As the mathematician Richard Courant commented, after viewing a prototype of a 1950s rocket design based on throwing little nuclear bombs out the back to push the rocket forward:
Zis is not nuts, zis is super-nuts.
But Wait, It Gets Much Worse
In practice, biomass crops will typically entail large monoculture farms (e.g. corn), requiring fertilizer, irrigation, etc.
The large land usage has huge impacts on ecosystem health, biodiversity, deforestation, etc.
The climate benefit is often negligible. For instance, in the wake of the 1970s energy crisis, the US began planting corn for conversion to ethanol (which is then mixed into the gasoline supply). This has long been notorious for its various harmful impacts. From a Reuters article last year:
The research, which was funded in part by the National Wildlife Federation and U.S. Department of Energy, found that ethanol is likely at least 24% more carbon-intensive than gasoline due to emissions resulting from land use changes to grow corn, along with processing and combustion.
“24% more carbon-intensive than gasoline” is not a ringing endorsement for a supposedly renewable energy source. The US really ought to stop doing this.
I Just Don’t See Two Sides to This Question?
Based on the data we found, I’m here to say that growing crops explicitly for use as biomass for electricity production is a ridiculous idea, absolutely inane, and it’s a waste of time to even talk about it. I usually try to talk about what I’m in favor of, rather than what I’m against; there’s plenty of room to try multiple approaches. But dedicated biomass strikes me as a “solution” with very little room for benefit of the doubt, and it’s absorbing substantial resources right now.
It’s true that biofuels, unlike (say) wind or solar power, can be easily stored. However, there are a lot of other ways to address the storage problem, that don’t have nearly as much environmental impact as dedicated biomass3.
So if anyone ever tries to talk to you about dedicated biomass as a source of electricity, please point them at this post – here’s the link, it’s climateer.substack.com/p/biomass – and ask them to either refute the math, or drop the subject and never bring it up ever again.
If you think I’m looking at this the wrong way, let me know in the comments! I promise to take feedback seriously; if I’m wrong about this, I really would love to know it, and I promise to update the post. It follows that if you’re reading this paragraph as it currently stands, then no one has provided me with an even vaguely plausible argument that devoting land specifically for the production of biofuels is anything other than a straight-up bad idea.
FWIW, Bill McKibben seems to agree.
You can find our detailed research notes here. Again, we’ll be covering this in more detail in the next post.
Except for wind power using the “spacing” measurement, for which the highest estimate was 127 m²/MWh/y: still 4.6x less land than biomass. In any case, when taking into account that wind power can overlap with other uses of land, “spacing” is typically not the best way to think about the impact from land usage.
For instance: batteries, hydrogen, ammonia, e-fuels, dispatchable demand – to name only a few.