Locking away the carbon

The IPCC has acknowledged that along with other mitigation options, Carbon Capture and Storage (CCS) could make significant reductions to GHG emissions. Geological storage is the preferred option as there are still large amounts of uncertainty regarding storing CO2 in deep oceans.

Carbon capture firstly involves capturing the CO2 directly from emission sources e.g. power plants and large industrial plants. The C02 is then dehydrated, compressed and transported and then finally injected into a reservoir. The capture and transportation is relatively easy, it is the storage part that is providing an obstacle and is causing concern.

Underground C02 of any kind must take place in sedimentary rock. Figure 1 shows the sedimentary basins of the world where CO2 could potentially be stored. C02 must also be stored deeper than 800m below the surface. Oil fields, gas fields and saline formations have been proposed as storage sites (Marchetti, 1977). Approximately 30 to 50 million metric tonnes of CO₂ are injected annually in the United States into declining oil fields. Both the report from the IPCC and House, et al. (2006) conclude the storage capacity for C02 is expected to exceed available fossil fuel reservoirs. Lenton and Vaughan (2009) postulate that in the long-term, carbon capture and storage could potentially sequester >1000 PgC.

Out of all the Geoengineering options discussed, the option of CCS appears to be the most researched, tested, implemented and supported. The backing and investigation by the IPCC has provided confidence in this option. In 2008, a German Power Plant run by Vattenfall conducted a pilot study through creating a CCS power plant. It was found that this plant reduced emissions of C02 by 80-90% compared to a power plant without CCS (IPCC, 2005). However, as with all of the other Geoengineering options discussed, there are downsides....firstly, capturing and compressing CO2 requires large amounts of energy. The amount of fuel required to operate a CCS plant would need to increase by 25-40% (IPCC, 2005). Secondly, there are numerous health and safety risks regarding storage, and many long-term uncertainties. For example, a big uncertainty regarding the use of deep oceans for C02 storage is the impact that this may have on ocean acidification.

Compared to many of the Geoengineering options investigated, CCS is the first one that I feel confident about. But is this because it has the backing of the IPCC? Compared to the other options were a few academics are leading the research, the IPCC appears to be taking point, bringing a variety of academics together to discuss and research CCS...so maybe Geoengineering is not all bad news!