Bioenergy with Carbon Capture and Storage (BECCS) Part 2

Last week I introduced the geoengineering technique which is typically seen as the least controversial; Bioenergy with Carbon Capture and Storage. BECCS is nicely summarised in the diagram below, showing how carbon is removed from the atmosphere by growing biomass for fuel and energy production. The carbon released during production is then stored, so it does not go back into the atmosphere. Considering BECCS as a carbon dioxide removal (CDR) technique, plants seem a natural way to hoover up excess CO2 from the atmosphere. So what’s the catch?

The BECCS process (Sanchez et al., 2015)

 

 The BIG picture

Unfortunately, planting a few fields of energy crops will not bring down enough atmospheric carbon to meet the ‘well below 2^oC’ target. It requires large scale implementation. According to Anderson and Peters (2016), to reach the 2100 target by removing 3.3GtCyr^-1 (gigatonnes of carbon per year), we would need land 1-2 times the size of India for growing biomass. The picture below shows how big this is in relation to Europe on thetruesize.com (which removes the typical size distortions of 2D maps).

  The size of India in comparison to Europe (thetruesize.com,2016)

Kemper (2015) identified:

Sustainable BECCS could positively impact…	Unsustainable BECCS could negatively impact…
Climate change Economy Agriculture Social inequality	Climate change Biodiversity Agriculture Social inequality

 

Climate Change?

 

You may have been surprised to find climate change in both columns. After all, the whole purpose of BECCS is to reduce climate change. However, Kemper (2015) highlights that BECCS can directly and indirectly increase greenhouse gas (GHG) emissions through changing land use. Land use change is already the second largest CO₂ emitter after fossil fuels, and would likely increase if BECCS were implemented on a large scale. Direct effects occur when the existing biomass is removed, releasing carbon to the atmosphere by decomposition, decay or combustion. Carbon release from soils is determined by subsequent treatment of the land, highlighting the need for sustainable BECCS. Furthermore, changing biomass can reduce the albedo of the land, which means the land reflects less solar radiation and absorbs more solar radiation, increasing warming. The graph shows Forest BECCS implemented in boreal environments cause the largest albedo changes.

 



Types of BECCS and the changes in albedo (Smith et al.,2015)

In addition, increased emissions from indirect land use changes can occur if arable land is cultivated for biomass production instead of food. Crops would have to be cultivated elsewhere, which could lead to deforestation releasing more stored carbon. Tight policies protecting global forests would need to be implemented to avoid this happening, especially because the population is expected to increase to 11.2 billion by 2100, increasing arable land demands. Presently, there is a big question mark over whether this issue could be resolved if it is to be implemented on the scales required to meet the targets, especially if BECCS could be rolled out as early as 2030.

 

Economy vs Biodiversity

 

BECCS is largely promoted as ‘cost-effective’. BECCS supporters are quick to highlight electricity generates revenue, making it more economically desirable than other carbon-negative methods. Furthermore, the carbon-negative element makes it more efficient than fossil fuels with CCS, but still allows continued fossil fuel use for a while. This avoids the economic challenges from a quick switch from fossil fuels to renewables. Sanchez et al. (2015) use North America as an example, predicting that the price per unit of power in a limited emissions scenario would be 1.3 times higher without BECCS, than with BECCS. However, the fossil fuel industry is also highly profitable, so a switch to BECCS will not occur without a large nudge. The nudge being a price or tax on carbon emissions (carbon tax), with specific subsidies for BECCS to trigger development in BECCS and the surrounding infrastructure. Then the costs associated with BECCS would begin to fall as it becomes more widespread.

 In contrast, biodiversity impacts are largely negative if poorly managed. Anderson and Peters (2016) suggest changing land use and increasing monocultures could cause biodiversity losses on a scale equivalent to the losses induced by 2.8^oC global warming. It seems bizarre to propose a method which accelerates a change we are trying to avoid. Then again, we are currently on a path to 4^oC warming, where the biodiversity impacts would be much harder to manage locally, so is it a case of the lesser of two evils?

 

Agriculture and Social Inequality

 

Biomass production replacing valuable arable land would affect GHG emissions, but it would also impact food prices. Studies such as Muratori et al. (2016) have investigated potential BECCS impacts on global food prices and the links to carbon taxes. They highlight that higher carbon taxes increases demand for bioenergy as it becomes the cheaper alternative to fossil fuels. This results in competition for land, causing higher food prices. Similarly, competition for water and nutrients can further increase prices, with the graph below illustrating the type of BECCS chosen has large implications. As a result, diets could become even more differentiated, with only the more affluent being able to afford the more land intensive meat, increasing social inequality. However, Nijsen et al. 2011 suggests that on a smaller scale bioenergy crops could be grown on degraded lands that cannot support crop growth. This would not only reduce competition but could positively impact the natural environment. 

Types of BECCS and the nutrients and water required (Smith et al., 2015)

 How I would proceed

In my opinion, BECCS could and should become part of our climate mitigation plan. I don’t think that it is a long term solution or an excuse to continue emitting emissions at the rate we are now. However, the majority of the issues raised are in relation to the huge scale proposed. On a smaller scale, mainly using degraded land, I think it could be useful to help the transition to renewables. I may be feeling particularly optimistic because the Paris Agreement has come into effect, but we are heading in the right direction and I feel sustainably managed BECCS could be a part of it. What do you think?