You say BECCS, I say BiCRS (or vice versa)
Despite being a nascent industry, the field of Carbon Dioxide Removal (CDR) is already rife with controversies and disagreements: Is the energy requirement of DAC prohibitive? What is the best storage of CO2? What is the exact CO2 drawdown of kelp? And: is BiCRS better than BECCS?
I believe arbitrary popular judgement and silly internal feuds are premature and counterproductive: in the end, solving the climate crisis will require a whole spectrum of technologies to take CO2 out of the environment, and store it away safely and permanently. There are no clear winners yet (and there might never be).
In this piece, I want to talk about the perceived competition of BECCS (Bio-Energy with Carbon Capture and Storage) against BiCRS (Biomass Carbon Removal and Storage) — or is it the other way around? — and why both umbrella terms are more similar than often portrayed.
First came BECCS
BECCS (Bio-Energy with Carbon Capture and Storage) was one of the first technologies to be widely proposed as a “negative CO2 emissions technology” (NETs), for instance in the IPCC’s 5th Assessment Report (2014).
The name says it all: you’re generating energy (electricity and/or heat) by burning biomass, then capturing the CO2 and storing it underground (CCS). The process isn’t all that different from how energy is produced with fossil fuels, apart from the fact that CO2 is removed from the atmosphere instead of added.
However, from its very proposal, the technology came with a lot of criticism.
Burning biomass often means cutting trees, moving a lot of material around and/or competition with agriculture. Moreover, the global energy demand is so enormous that the ground surface needed to grow all this biomass seems prohibitive. The last three letters in the acronym, “CCS”, are also still controversial for a lot of people. And despite the idea being around for a long time, BECCS still needs to deliver on its promise at scale.
Then came biochar
A lot of the criticism above can and should be put into more perspective. There are places where BECCS make a lot of sense, where it can be done sustainably.
However, there is one more argument that is more difficult to refute, namely that biomass is too precious to simply be burned. Nature takes months or years to build up these intricate, complex and versatile materials, only to be oxidized into CO2 and H2O in seconds. Regardless of how you turn this, the complete destruction of value is a pity.
Wouldn’t it be possible to draw down CO2, while also make something more useful in the process?
In comes biochar, and other BiCRS (Biomass Carbon Removal and Storage) technologies, converting the biomass into a solid with a further use, effectively combining storage with utilization. Biochar not only fixes CO2 in the ground, it can also improve the health of agricultural soils, by fixing nutrients, improving water retention and providing a habitat for soil organisms. Clearly a win-win.
But what is the difference?
As a chemical engineer, I don’t see the difference in the same way. For me, both acronyms describe methods using biomass as a carbon vehicle to move CO2 from the atmosphere (through photosynthesis) into long-term storage, and creating some form of useful by-product in the process.
In essence, you can “cook” biomass in different products, and you’ll never have one or the other — it will always be some kind of mix. When biomass is combusted, by-products are inevitably created: some gases other than CO2, some solid. Likewise, in pyrolysing biomass to bio-char, a lot of CO2 and by-gasses (NOx, SOx, CO, CH4 etc) are formed.
The process parameters can be tuned in a way that favors one product over another (indications in parenthesis, the real system is much more complex):
- Oxygen content (higher oxygen, more combustion)
- Water content (more water, more conversion to syngas, bio-oil)
- Temperature (higher temperature, faster process)
- Closed/open setup (more closed, more solids)
And of course, all technologies have a number of pros/cons, some of which apply to more than one technology.
Another big difference between the technologies, is the way they can be implemented.
For BECCS, you need scale. Not so much for burning the biomass, but for converting the heat into electricity through large steam turbines, and for distributing the electricity afterwards, and finally, for capturing and sequestering the CO2. However, these power plants constitute extremely complex projects costing hundreds of millions of dollars, prone to delays and budget overruns.
At the other hand of the spectrum: biochar — which can be done in a artisanal fashion within the confines of a field: from collecting the biomass, running the pyrolysis, and plowing the biochar back into the ground (as a side-note: making biochar is probably as old as agriculture itself). This obviously is much less capital intensive. However, it also is much less efficient: for every tonne of CO2 sequestered, a tonne of CO2 might be emitted into the atmosphere again to generate the heat for the pyrolysis. Moreover, a lot of noxious and harmful substances are co-created.
In between, there is a process like Charm Industrial’s: mobile units to convert biomass into a bio-oil, which can be injected in small oil reservoirs. This approach works wonders in places like the American mid-west, where agriculture and oil production co-exist.
Fighting the climate crisis is complex. There is no good and evil way to use biomass in this nonlinear, dynamic chaotic problem, it really depends on a multitude of parameters what use is better where and when and how. While public acceptance of the technology and climate justice of the implementation are crucial for any climate solution, let’s not fall into the trap of creating arguments where there aren’t any.
Sometimes, a potato is a potato, and any potato will do to make the potato salad.
Lennart Joos is breathing CO2 (literally and figuratively) and has been working on the topic for over 10 years in a variety of settings. Most recently, he is the founder of CO2 removal start-up Out of the Blue. Always open for collaboration, you can reach him on firstname.lastname@example.org or via Twitter @lennartjoos or LinkedIn.