This is part two of a three-part essay on CCS by Dr Stephan Singer. Read part 1 here.
Part 2 – Coal, CCS and the power sector
As mentioned in part 1, while there may be a case for carbon capture and storage in the industrial sector, in the power sector, it does not contribute to solving many other environmental problems that coincide with coal usage.
In drier countries and regions of the world, freshwater supply is increasingly constrained and scarce. Coal with CCS needs significantly more water for cooling than a conventional coal plant. The International Energy Agency (IEA) has shown that the power sector is now responsible for about one quarter – and rising – of freshwater use. Freshwater is direly needed for other purposes such as human demand, agricultural irrigation for food security and securing biodiversity in rivers.
Further, conventional air pollution from coal is generally only slightly reduced by CCS and would require additional investments for “clean” coal. By comparison, wind, solar and geothermal energy in closed circles do not need any freshwater supply in the operational phases nor do they generate any hazardous air pollution and any toxic or solid waste (like fly ash from coal).
There are also electricity system inertia that advise us to not rely on coal with or without CCS in a decarbonised economy. Independent of whether this happens sooner or later, the fact remains that most countries are increasing the output of weather-dependent renewables such as solar and wind. To balance that growing variability and maintain system reliability for a safe power supply, other power sources like coal or gas need to be increasingly ramped up and down over the day to follow the consumers demand curve.
While fossil gas turbines might comply with these needs within few minutes, nuclear and coal as classical baseload supply sources can’t hardly do so without major losses in efficiency. Their technologies are not made for a world with growing dispatch-based renewable electricity on demand.
The consequence for coal power is that this energy penalty grows CO2 emissions per kWh, because the plant is not operating permanently in an ideal and permanent high boiler temperature zone. If the plant is equipped with CCS technology, its CO2 capture efficiency is likely to be reduced significantly as well, and the claim of a “low-carbon” technology becomes questionable. This is also true for a gas plant as well, if ramped up and down regularly.
There are fundamental system conflicts in power supply – one can’t have coal, nuclear and a large fleet of wind and solar to secure grid stability for the consumer.
Lastly, there are many uncertainties associated with safe and reliable CO2 storage in respective geological formation and the need for century-long monitoring. We know from calculations by the UK-based Hadley centre and others that stored CO2 can’t exceed a leakage rate of more than 0.01 per cent annually to be environmentally effective for its purpose. That sounds very low, but at least 40 per cent of CO2 remains in the atmosphere for more than 1000 years.
There are therefore good reasons why WWF demands that coal for power production must be terminated by 2035 at the latest in OECD and Russia, and that after 2030 there is a rapid decline of coal in all remaining mainly developing countries.
Some stakeholders argue that this position should be valid only for “unabated” coal – but we say that all coal needs to go eventually, with or without CCS, to not undermine our call for 100 per cent renewables by 2050.
Dr Stephan Singer is WWF International’s director for global energy policy. email@example.com
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