Carbon capture and sequestration (CCS)

28 04 2014

Mark Cochrane

Mark Cochrane

Another guest post from Mark Cochrane on one of the cornucopians’ favourite solutions to our climate predicaments, Carbon capture and sequestration, better known by its acronym CCS….

Carbon capture and sequestration (CCS) is the great hope for so-called “clean coal” as well as a potential way of removing CO2 from the atmosphere. Methods vary, but the basic idea is to capture the emissions from a coal-fired power plant and separate out the CO2 and acid rain-producing sulfides. These gases are then compressed into a liquid form that is shipped somewhere and subsequently injected underground. In principle the atmosphere could be scrubbed of CO2 in a similar manner. Makes you wonder why we aren’t doing this already…

If it works, the carbon will be gone from the atmosphere, so what is the problem? The purpose of a power plant is to produce…..power. As we all know, it takes energy to mine, process, and ship coal to the power plant. When burned, there is only so much efficiency you can get in converting the heat to usable energy (e.g. electricity). In 2008, the average efficiency was 32%, best plants (top 10%) were 37.4% efficient.

Well, surprise, surprise. It actually takes energy to capture, compress, store, transport, and pump the captured gases underground. If the energy spent on CCS processes exceeds the net power generated by the power plant then the process is completely untenable. Even if you can make the process work with a positive EROEI you still have to account for the lost energy. In other words, if you still need the same amount of disposable energy from the power plant to support your consumers then you need to burn even more coal to offset the CCS energy losses.

No free lunch here. The energy expenditures for CCS increase with the level of CO2 capture efficiency that we want to achieve. These energy expenditures need to be made up by mining, processing, shipping and burning even more coal than we are using today.

What about the oceans? They are a good place to bury carbon aren’t they?

The ‘iron hypothesis’ was put forth by John Martin in the 1980s and first tested in the open ocean in 1993. The idea is that large sections of the ocean are impoverished of iron, so seeding the ocean surface with iron should make phytoplankton bloom, soak up carbon, die, and sink, thereby drawing carbon out of the atmosphere. “Give me a half a tanker of iron and I’ll give you the next ice age,” Martin once said jokingly.

The idea has been tested in many locations since 1993 and the results support the theory insofar as the phytoplankton do respond and bloom after adding iron to the waters.

It works, so what is the problem? Phytoplankton blooms have met or even exceeded predictions, however, there are impacts on the composition of the ecosystems involved and the nutrients consumed are no longer available for other organisms that would have used them in down current locations. Ultimately though, the main problem is that very little of the ‘fixed’ carbon actually reaches the deep ocean or seafloor. Mixing keeps the particulates from coagulating and zooplankton graze and recycle the carbon. It comes back to the atmosphere as CO2 again.

Even in the best of cases, it would be necessary to fertilize an area of roughly twice the surface of the Earth to significantly offset fossil fuel-based carbon emissions. Beyond the physical impossibility of this, and the exorbitant costs of maintaining a fleet of ships dumping the worlds iron ore into the oceans, concomitant emissions of nitrous oxide (another greenhouse gas) caused by the iron seeding could offset many of the ‘gains’. Many regions of the deep oceans could also experience anoxia.

In short, this is no panacea.

On Geoengineering the future

This has showed up in the final paragraph of the Summary for Policymakers of WG1 for the latest IPCC assessment report (AR5).

“Methods that aim to deliberately alter the climate system to counter climate change, termed geoengineering, have been proposed. Limited evidence precludes a comprehensive quantitative assessment of both Solar Radiation Management (SRM) and Carbon Dioxide Removal (CDR) and their impact on the climate system. CDR methods have biogeochemical and technological limitations to their potential on a global scale. There is insufficient knowledge to quantify how much CO2 emissions could be partially offset by CDR on a century timescale. Modelling indicates that SRM methods, if realizable, have the potential to substantially offset a global temperature rise, but they would also modify the global water cycle, and would not reduce ocean acidification. If SRM were terminated for any reason, there is high confidence that global surface temperatures would rise very rapidly to values consistent with the greenhouse gas forcing. CDR and SRM methods carry side effects and long-term consequences on a global scale. {6.5, 7.7}”

This bit about geoengineering apparently was added at the behest of Russia but the US has been interested in elements of this for a while is well. The U.S., U.K. and other countries are already funding research into a variety of climate engineering approaches. This should be outside of the mandate of the IPCC but such things are malleable where political considerations are concerned.

For those who do not know, geoengineering in this context refers to intentional planetary climate engineering. Traditionally, responses to climate change have been classified in terms of mitigation and adaptation. Mitigation is doing things like reducing fossil fuel emission so that the future climate changes will not be as severe as otherwise expected. Adaptation is admitting the inevitability of climate changes and actively doing things to prepare, like planning for flooding or heatwaves.

Geoengineering is a third option where we try to ‘fix’ the climate through various technical schemes. A quick fix and we will not have to change anything. Party on! There are three major reasons (besides ethics) that such approaches have been marginalized to date; expense, side effects, and what economists term moral hazard.

Moral hazard is the tendency to be more willing to take a risk, knowing that the potential costs or burdens of taking such risk will be borne, in whole or in part, by others. In terms of climate change, it is the idea that knowledge that geoengineering is possible could lead to climate impacts seeming less fearsome, which could in turn lead to an even weaker commitment to reducing greenhouse gas emissions.

The fact that governments are agitating for the inclusion of geoengineering in the IPCC reports seems a clear indication that they feel it will be easier to sell technical ‘fixes’ than the pain of reduced fossil fuel use.

Followers of this thread already have some understanding of the complexity surrounding greenhouse gas-related climate change. While we have a good idea of the energy balance issues, the actual ways in which these changes will ripple through, affect, and be affected by earth system processes and ecological changes are only now being uncovered. Feedbacks in the system are poorly defined even where they are known. Now imagine implementing several simplistic ‘solutions’ designed to intentionally alter global climates at the same time as we continue our present global terraforming experiment of fossil fuel-based climate manipulation. The impacts of these ‘solutions’ are poorly if at all known. Shoot from the hip and hope for the best.

What could possibly go wrong?

I’ll try to add another post or two explaining some of the proposed approaches to ‘fixing’ the climate so you can decide if you think this is a good idea.

Advertisements