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ISIS Report 11/07/08
Renewables versus Carbon Capture
and Storage
A study commissioned by the German federal government finds carbon capture
and storage emits ten to forty times as much greenhouse gases as wind or solar
energy and gives no protection against the rising cost of fossil fuels Dr. Mae-Wan Ho
The study commissioned by the German federal government and led by researchers
at the German Aerospace Center in Stuttgart compared carbon capture and storage
(CCS) with renewable energy technologies using a combined lifecycle analysis
and cost assessment for Germany [1].
The results show that per KWh of electricity generated, CCS cuts
CO2 emissions by 72-90 percent, and total greenhouse gas emissions
by 65-79 percent, assuming that the technology works as planned and the geologically
stored CO2 does not leak out at all; any leakage would compromise the mitigating
potential of CCS. However, the net emissions from CCS are still 10 to 40
times those from renewable energies such as solar and wind (see Figs. 1 and
2).
Figure 1. Carbon dioxide emissions
for coal and natural gas power stations with and without CCS compared with
renewable wind and solar
Figure 2. Greenhouse gas emissions
for coal and natural gas power stations with and without CCS compared with
renewable wind and solar
The difference between CO2 and greenhouse gas emissions
comes from the methane released when coal is mined; and methane has a global
warming potential about 20 times that of CO2. If companies take
steps to prevent the release of methane and capture it for use in combined
heat and power generation plants, then the advantage gained is equivalent
to fitting CCS for lignite power plants.
Assuming that CCS could be fitted to new IGCC and Natural Gas
Combined Cycle (NGCC) plants by 2020, electricity would end up costing roughly
twice as much as without CCS. While renewables are currently more costly,
the improvements in technology would bring the price of electricity from offshore
wind plants for example to half the price of fossil fuel plants with CCS.
The advantage of solar and wind energies is that they are immune from price
increases of fossil fuels.
The assumption that the first commercially operated power plant
with CCS will be operating by 2020 is built in to the study because Germany
faces the problem that a large number of its fossil power plants are reaching
the end of their life in the next 15 years. So, only if CCS technology can
be retrofitted by 2020 would it stand a chance of delivering the climate protection
goal of reducing greenhouse gas emissions at all.
Unfortunately, CCS remains unproven as a technological package.
The earliest possible deployment is 2030 according to the World Business Council
for Sustainable Development, while the Intergovernment Panel for Climate Change
does not expect CCS to be commercially viable before the second half of the
present century (see [2] Carbon Capture and Storage,
A False Solution, SiS 39).
When further impacts are factored in [1] CCS increases photo-oxidants
(that damage DNA), eutrophication (that destroy aquatic life), acidification
(that damage trees and other plant life), and toxicity to humans, all by about
40 percent.
References
- Viebahn P, Nitsch J, Fischedick M, Esken A, Schüwer D, Supersberger N,
Zuberbühler U and Edenhofer O. Comparison of carbon capture and storage
with renewable energy technologies regarding structural, economic, and ecological
aspects in Germany. International Journal of Greenhouse Gas Control 2007
(article in press)
- Ho MW. Carbon capture and storage, a false solution. Science in Society 39 (to appear).
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