Using agricultural land for anything but growing food or fiber for human consumption (including indirectly for livestock feed) is taboo to many. The ethics and economics of using land to grow crops for biofuels (e.g. sugars, starches, oilseed), which makes up about 8% of ag land (1.4B acres) has been hotly debated for decades. Nowadays discussions and action is starting to coalesce around growing crops that can draw down vast amounts of of CO2 in a single growing season which can be used to sequester carbon via biochar, BECCS or more recently, as buried biomass. I suspect the food vs fuel debaters will soon begin to debase the food vs future furor.
My own opinion on the value and financial viability of purpose-grown feedstock for CDR has evolved over the past several years. If you’d asked me 5 years ago about doing this, I would have said the economics won’t work. All the costs of growing feedstock (not to mention the water and nutrients needed) would make the price of the biochar too high for most markets, particularly agriculture. But with the average price of biochar-based removals hovering around $150 per ton of CO2e (so double that – at least – to get the price per dry ton of biochar), carbon revenues puts paid to the financial viability argument.
Land use conversion is still a concern, but fortunately biochar protocols are so far guarding against converting forests into farmland for feedstock (may that continue!). That said ‘waste’ organic material is plentiful and carbonizing it is an increasingly attractive way to rapidly reduce volumes, toxins and eliminate methane emissions from waste organics, particularly wet ones, while converting up to half of the CO2 absorbed during the plant’s lifetime into much more stable carbon. Why focus on purpose-grown feedstocks if this is the case? Given the dire need to rebalance carbon and the dearth of safe, scalable and shovel-ready solutions available RIGHT NOW, I no longer think in terms of ‘either/or’ when it comes to climate action. Much as I believe there are (and we need) dozens of removal solutions, time is not on our side as the ever-worsening climate is clamoring to show us.
Some of the most compelling reasons to consider using purpose-grown crops for carbon sequestration can be found in the readiness and speed it offers. Woody biomass is by far the most common feedstock currently used to produce biochar (and likely BECCS and burials too). Much of this is considered either a hazardous fuel (e.g. vast stretches of standing dead trees) or a waste material (e.g. green waste, sawmill residues, etc.). But a typical forest will only drawdown ~1t of carbon (3.67t of CO2) per acre, per year. For as long as the forest is still standing or the material isn’t burned, it prevents this accumulated carbon from returning to the atmosphere and provides countless other eco-system services as well. But this reservoir of carbon is increasingly at risk. Each year hundreds of millions of acres of forest are decimated by fire, sending the vast majority of decades worth of stored carbon skyward in a blaze of smoke and soot.
By contrast, certain annual crops have significantly higher drawdown capabilities. Some types of hemp can withdraw 6 – 10 tons per acre of CO2 in just 6 months. This week I spoke with Joe James, CEO of Agri-tech, and learned that biomass sorghum can remove double that amount. In some locales you might even be able to have 2 harvests per year. Bamboo is another super accumulator. Adding the biochar produced back to the soils used to grow the biomass for the first few years could reduce water requirements while optimizing soil resiliency and yields. Utilizing the vast amount of degraded lands could not only help drawdown vast amounts of carbon in this decade but done right, this could also help restore these lands to enable better, safer food production.
No one knows when tipping points will be reached, but the increasing signs of climate chaos are pretty strong indicators that we need to act with speed, focus and efficiency now. We have at our disposal today the means and mechanisms to draw down vast amounts of carbon and convert it into geological storage as well as producing renewable energy, so let’s ‘Direct the Rider, Motivate the Elephant, and Shape the Path’ as the Heath brothers advise in Switch: How to Change Things When Change is Hard.
