Today, nearly 70% of announced carbon removal contracts are for one technology: bioenergy with carbon capture and storage (BECCS). Basically, the idea is to use trees or some other types of biomass for energy, and then capture the emissions when you burn it.
While corporations, including tech giants like Microsoft, are betting big on this technology, there are a few potential problems with BECCS, as my colleague James Temple laid out in a new story. And some of the concerns echo similar problems with other climate technologies we cover, like carbon offsets and alternative jet fuels.
Carbon math can be complicated.
To illustrate one of the biggest issues with BECCS, we need to run through the logic on its carbon accounting. (And while this tech can use many different forms of biomass, let’s assume we’re talking about trees.)
When trees grow, they suck up carbon dioxide from the atmosphere. Those trees can be harvested and used for some intended purpose, like making paper. The leftover material, which might otherwise be waste, is then processed and burned for energy.
This cycle is, in theory, carbon neutral. The emissions from burning the biomass are canceled out by what was removed from the atmosphere during plants’ growth. (Assuming those trees are replaced after they’re harvested.)
So now imagine that carbon-scrubbing equipment is added to the facility that burns the biomass, capturing emissions. If the cycle was logically carbon neutral before, now it’s carbon negative: On net, emissions are removed from the atmosphere. Sounds great, no notes.
There are a few problems with this math, though. For one, it leaves out the emissions that might be produced while harvesting, transporting, and processing wood. And if projects require clearing land to plant trees or grow crops, that transformation can wind up releasing emissions too.
Issues with carbon math might sound a little familiar if you’ve read any of James’s reporting on carbon offsets, programs where people pay for others to avoid emissions. In particular, his 2021 investigation with ProPublica’s Lisa Song laid out how this so-called solution was actually adding millions of tons of carbon dioxide into the atmosphere.