Feedstock is Finite
We have a problem. Biomass supply is limited and everyone wants to use it.
Last month, carbon removal experts ranging from academics, policymakers, economists and investors gathered for the UK’s greenhouse gas removal event. Bioenergy with CCS has been identified by the UK as a key strategy in meeting NetZero targets, with the UK's Climate Change Committee (CCC) indicating its potential to remove 20 to 70 Mt CO₂ each year by 2050. However, a question that surfaced during the event was about the supply of consistent sustainable biomass feedstock and competition for its use.
The support for bioenergy comes at a time of a global shortage of the main current feedstock, wood pellets, which is exacerbated by the war in Ukraine. A recent LCA sheds some light on the uncertainties of BECCS theoretical potential. When using local, sustainable biomass — rather than shipping wood pellets across the Atlantic — BECCS can only deliver 23% of its minimum potential outlined by the CCC.
At Counteract we have been exploring the potential of BiCRS, the group of biomass based carbon removal pathways encompassing BECCS among others (read why we prefer BiCRS here). We believe it makes sense to capitalise on nature’s own carbon capture solution — photosynthesis — as much as possible. However, photosynthesis requires land for growing and, between food and feed production and other nature-based solutions, like habitat restoration, competition is heavy.
There have been many estimates for the potential scale of BiCRS and the key limiting factor on each is sustainable feedstock supply. Perhaps the most realistic estimate we have seen is from the Environmental Technology Council (ETC) at 1.3 Gt CO₂ pa. It assumes no conversion of current land uses for CDR and assesses the competing priority demands for crop and forestry residues.
As BECCS and BiCRS applications are developed and built out, anything we can do to increase the availability of sustainable biomass will directly increase the potential scale and benefits. A selection of innovative ideas we have come across for this that might help bump up the overall potential of BiCRS include...
Biomass crops on marginal land
Growing biomass feedstock in degraded marginal areas is not a new idea. It is attractive because sustainably repurposing degraded marginal land does not compete with food production. Instead it can bring new revenue opportunities to degraded areas and by selecting the correct species can revitalise the land.
The amount of marginal land available and the definition of what constitutes marginal is debated. Grasslands, for example, are sometimes called marginal. However, studies have shown that converting grassland to perennial BiCRS feedstock can have an overall negative effect on soil carbon stock and therefore impact the net carbon removal. By contrast, soils that have depleted carbon stocks, like croplands, show greater potential for additional carbon sequestration.
At Counteract, we define marginal land as not economic for food production, not biodiverse, depleted in carbon stock and/or where BiCRS crops could achieve more positive services than traditional cropping systems through improved soil, habitat, water or air quality, or socioeconomic opportunity.
Other options for marginal land could include rewilding; however, this is not always possible. For example, in Australia there are huge areas incapable of supporting life due to secondary salinization. Agricultural intensification coupled with low rainfall results in higher rates of evaporation, which has left the soils 5x saltier than the sea. InterEarth are reinstating native tree species that can tolerate the tough conditions, coppicing them to increase per tree productivity and then pickling them in the salty soils. There’s approximately 3 million hectares of this type of marginal land in Western Australia alone.
Hemp
Hemp is a unique crop, appealing for its multi-purpose applications, rapid growth rates and low inputs. It can be used as a cover crop to improve soil quality, eliminate weeds, and provide additional revenue opportunity. Hemp also produces 2-10t of waste straw per hectare. Pyrolysing the straw to produce biochar could yield durable sequestration of ~2-10 tCO₂e/ha/yr in addition to gains in soil carbon - for comparison, cover crops on their own improve soil carbon by ~1tCO₂e/ha/yr and we do not know the durability.
Marine Biomass
Algae might have untapped potential as a BiCRS feedstock due to efficient productivity (microalgae can double their biomass in 3.5 hours!), and no competition for land and water. The CDR potential of marine biomass is difficult to determine but in theory seaweed alone could sequester an extra 1-10Gt CO₂e. Scale up is currently limited by high cultivation costs and there are still questions about the effectiveness and potential ecological impacts this approach.
Aside from the more commonly referenced seaweed sinking, some interesting innovations we are seeing in this arena include mimicking algal blooms in contained offshore environments and using synthetic biology to maximise algal growth rates.
Other organic carbon wastes
Unexplored organic waste streams might offer another opportunity for BiCRS. Municipal waste, including waste textiles is one example. In the US, over 10 million tonnes of clothes end up in landfill each year. However, there is still scepticism over municipal waste’s potential for BiCRS because contaminants can disrupt the efficiency of the conversion process.
Invasive species
The great sargassum belt, spanning 9,000km across the gulf of Mexico is the world's largest seaweed bloom, amassing shy of 10 million tonnes of biomass. With huge quantities washing up on the shores of the Caribbean, clean-up is a burden. South Africa is another example with over 14 species of invasive Australian Acacia. Burning is the current management strategy. However, turning these invasive species into biochar, which has potential co-benefits when applied to soils like improved fertility, offers an elegant alternative. Evidently, not all countries will have a supply of invasive species but, for those that do, harvesting them for BiCRS could turn these pests into profit.
Unreachable biomass
Crop waste is frequently dispersed across a range of landowners and burning is often the most cost-effective way of dealing with it. Distributed biomass conversion facilities can help reach “stranded” biomass sources and is another solution that can help boost the potential of BiCRS. Takachar, for instance, is developing a distributed system for accessing crop waste.
These innovations are surely only the beginning. Some (very) basic back-of-envelope calculations using the above examples add an extra CDR potential of 1.15 Gt CO₂e and, although real world complexities will inevitably take hold, finding access to new, sustainable, cost-effective biomass is clearly a priority for unlocking the potential of BiCRS.
There are a few other considerations that we think should not be forgotten when thinking about the future availability of biomass:
As BiCRS continues to scale, increased competition for biomass is likely to result in higher costs. Today, waste biomass is often said to be a cheap resource, however we expect this to change, and commercial models will need to flex accordingly.
Local variations in biomass type and availability could cause unique challenges. Biomass scarcity, or competition, may be localised because transportation over long distances can be uneconomic — or environmentally destructive in itself! — and opportunities for production will also vary. Businesses will need to find the right location with viable access between feedstock, conversion site and local markets.
We do not expect one solution to take hold, a variety of feedstock and applications will likely help BiCRS meet scale.
At Counteract we are looking hard for businesses and entrepreneurs with new processes and new sources of biomass aimed at making the most of the carbon removal, economic and social improvement opportunities of BiCRS. If you have any ideas, get in touch!
