Greenhouse Gas Removal Technologies – approaches and implementation pathways in Scotland

Greenhouse Gas Removal (GGR) technologies which recapture already emitted greenhouse gases from the atmosphere and ocean, can play a significant role in meeting Scotland’s emissions goals.

This review provides a deeper understanding of the readiness of certain GGR approaches, and their potential applicability and implementation pathways in Scotland.   The report provides an explanation of five technologies that are potentially applicable in Scotland at scales of millions of tonnes of carbon dioxide (MtCO₂) per year: increasing soil carbon; creating biochar; capture and geological storage of CO₂ from biomass (BECCS); enhanced geological weathering of rock minerals (EWAM); and direct capture of CO₂ from the atmosphere for geological storage (DACCS). 

 

The report finds that:

 

• Soil and land use can be actively managed to provide a carbon sink that supports Scotland in achieving its climate targets.  Increasing soil carbon is a low technology option and many approaches that can achieve this goal are available and in place now (for example peatland restoration). The land use resource is finite and after a few decades it is likely that the potential for additional uptake will cease.

 

• Biochar is a mature technology with a high degree of feedstock flexibility.  Small to medium scale operations may be well placed to access widely distributed and cheap biomass resources however large scale biochar large scale contribution to GGR is likely to be limited by availability and competition of low-cost biomass to use as feedstock. 

 

• BECCS is an emerging GGR technology, encompassing a range of applications at different scales and stages of maturity. Large scale BECCS for low carbon heat or power in Scotland will be limited by competing demands for resources, a network of small-to-medium scale facilities may be more viable subject to managing competing biomass demands.

 

• EWAM offers a number of storage pathways to greenhouse gas reduction that may support Scotland’s longstanding agricultural, aggregate and heavy industries. However quarrying and transport implications may constrain the scale of application.

 

• DACCS is an emerging technology that is flexible and highly scalable. It is energy intensive and relatively costly however these costs are likely to fall as the technology matures. DACCS effectively sets an upper cost limit for greenhouse gas reduction.

 

The operation of BECCS and DACCS are reliant on a strategically planned CO₂ transport network and geological storage of CO₂ beneath the North Sea.