Carbon Sequestration – an optimal clean technology?


While coal-fueled power plants are directly responsible for roughly one-third of our CO2 emissions, the DOE indicates that coal is expected to dominate our domestic power generation at least for the next 25 years.  Globally, the increased demand for coal-fueled electricity will translate into a 57% rise in related CO2 emissions by 2030 according to the IEA.

One technology that attempts to solve the CO2 emissions crisis is carbon capture and storage, or CCS. Generally speaking, CCS captures the CO2 emissions from coal power plants and other industrial sites and injects the CO2 into underground porous rock formations in hopes of permanent sequestration.

Both the coal industry and the Obama administration endorse CCS.  Obama supported $3.5 billion for CCS of the $787 billion Stimulus Package and has made CCS a cornerstone of renewable energy policy.

“To prevent the worst effects of climate change, we must accelerate our efforts to capture and store carbon in a safe and cost-effective way. This funding will both create jobs now and help position the United States to lead the world in CCS technologies, which will be in increasing demand in the years ahead,” said Energy Secretary Steven Chu a few weeks ago.

Of course, the coal industry has a vested interest in promoting “clean” energy solutions that provide for continued use of and dependence on coal. But is CCS an optimal cleantech solution?

It’s expensive – conventional coal-fired plants are not configured to support the CCS solution. No CCS plants currently exist on a large commercial scale.  Plants that would readily support CCS by converting coal into gaseous form to allow capture of the CO2 emissions before gas is burned are very costly.

The CCS process is energy intensive itself – adding upwards of a 30% energy penalty to the production of electric power.  Thus, CCS perversely compounds the carbon problem it is intended to correct.

Further, questions remain as to the permanence and safety of sequestration.  Though generally not regarded as a toxic substance (apart from climate change impacts), CO2 if released into groundwater or the atmosphere can have harmful if not deadly effects. Most CCS experts agree that up to 20 demonstrations to test the technology would be required to ensure that safety concerns are addressed adequately, adding to the expense and delay of CCS commercial deployment.

CCS may be creating more jobs, but is this the best way to deal with coal’s effect on climate change?  What is the opportunity cost of CCS?  By pursuing CCS and our continued reliance on coal, are we making an investment that would better be made on technologies that themselves are clean?

[photo: flickr/davipt]



Have any Question or Comment?

7 comments on “Carbon Sequestration – an optimal clean technology?

Daniel Benitez

Explain: “…gaseous form to allow capture of the CO2 emissions before gas is burned are very costly….

CO2 is a product of combustion, how do you capture it before it is burned?

Daniel,

You are correct in saying that CO2 is a product of combustion – the point (I think) that Sharon is making is that by gasifying coal through pyrolysis (or other means – http://www.zetatalk.com/energy/tengy11a.htm) you capture some CO2 prior to combustion, and are rewarded for your efforts with a purer flue gas of CO2 (http://en.wikipedia.org/wiki/Flue_gas).

Thanks Daniel and Ian. The pre-combustion technologies are optimal. One key technology is IGCC (Integrated coal Gasification Combined Cycle)…now in support by the government and coal industry. IGCC converts fuel to hydrogen and CO2 prior to combustion. The CO2 can then be captured, and the hydrogen combusted to produce power. IGCC is expensive and only applies to new (and few existing) fossil fuel power plants. Another pre-combustion option is Oxyfuel, a process using pure oxygen in combustion. The flue gas in this process would contain mostly CO2 and water vapor, which can be easily separated. The limitation here is also cost since pure oxygen is expensive to produce .

Hope that helps.

Efforts to apply a single capture and sequester process to CO2 emissions increases risk. Nature uses many competing and complementary processes to elegantly manage byproducts of living systems. Humans are integral part of the living earth system. By including methods of carbon dioxide utilization to increase our planet’s effective conversion of sunlight to biological life. By emulating some of nature’s systems, CO2 can be used to help create topsoil and restore the earth’s ability to balance our GHG gas levels. With the current human population we now have enough people to correct the GHG rapid rise through the positive reward of ample food and fuel. Combined with increased energy efficiency standards and capture and use technologies, humans will provide a critical role in accelerating life’s evolutionary development. If you are not familiar with the Eprida ECOSS process, a two minute flash presentation at http://www.eprida.com will give you an overview. Presentations and publications on the site goes into the technical aspects.

Bilsko

Sharon,

Thanks for making the effort to elaborate on the details; not too many bloggers take the time to learn about IGCC and the intricacies of stoichiometry!

You’re right about coal gasification adding a substantial amount to the cost of a new plant or an existing plant retrofit. A recent issue of Diesel & Gas Turbine (I’m pretty sure it was that journal, will have to check to be sure) outlined two CO2 capture projects and the costs were astronomical: nearly $5000/kW! That’s almost as much as solar PV panels installed! Add the costs of Transmission and Distribution upgrades to that ($2000/kW for transmission and at least that much again for distribution). Add to that the costs of actually doing something with the CO2 and it quickly becomes far more expensive than other approaches.

make soil, go ahead use it, problem solved

(we might all end up trying to anyway, and that would pretty much fix it too)

http://www.vpt.org/programs/regen_collins.htm

Comments are closed for this post !!
Skip to toolbar