IPCC on natural gas

The "Summary for Policymakers" of the final part of the IPCC 5th Assessment Report has been released today. The IPCC AR5 is split into 3 volumes: the first focused on the physical evidence for climate change; the second on the impacts of climate change. This final part focuses on what we can do about it.

Unsurprisingly, the report calls for substantial increases in proportion of electricity generated from renewable sources. It also calls for increased levels of nuclear energy as "a mature low‐GHG emission source of baseload power".

Of most interest to this blog is the paragraph on natural gas:

GHG emissions from energy supply can be reduced significantly by replacing current world average coal‐fired power plants with modern, highly efficient natural gas combined‐cycle power plants or combined heat and power plants, provided that natural gas is available and the fugitive emissions associated with extraction and supply are low or mitigated (robust evidence, high agreement). In mitigation scenarios reaching about 450 ppm CO2eq concentrations by 2100, natural gas power generation without CCS acts as a bridge technology, with deployment increasing before peaking and falling to below current levels by 2050 and declining further in the second half of the century (robust evidence, high agreement).

This is a very strong statement. Not only must natural gas electricity generation stay at current levels, but its deployment must increase in the near term, with the amount of natural gas-fired power generation only returning to and dropping below current levels by 2050, almost 4 decades from now. This is true regardless of whether carbon capture technology is deployed at gas-fired plants. Development of CCS would further increase the need for gas:

Carbon dioxide capture and storage (CCS) technologies could reduce the lifecycle GHG emissions of fossil fuel power plants (medium evidence, medium agreement).

Note that the report categorises how strong the evidence, and the degree of consensus, for each statement it makes. These statements on natural gas have robust evidence, and a high level of agreement.


Also of interest is the caveat "provided that natural gas is available". The report sticks to discussing natural gas in general: it does not directly consider from where this gas will be sourced, and does not mention shale directly. However, it is clear that to have "deployment increasing before peaking and falling to below current levels by 2050", shale gas will have to be developed extensively.

While shale isn't directly mentioned in the SPM, comments in the press conference made by Ottmar Edenhofer, co-chair of the report, bear out these implications in terms of shale gas.

These comments have generated headlines this morning (Mail, Independent, Times, CityAM). The IPCC WGIII press conference is available online - the comments on shale come in at 53:42 (emphases mine):

We have in the energy supply also the shale gas revolution, and we say that this can be very consistent with low carbon development, with decarbonisation. That's quite clear.  But it is important to understand that the shale gas revolution has a different impact in mitigation or baseline scenario. In a baseline scenario if you have an additional supply of fossil fuels this will not help in the end, because if somebody deploys gas so other parts of the world might increase coal and in the end you're back in the business as usual scenario, and shale gas will not help. But gas can be very helpful as a bridge technology in mitigation scenarios, and this has been explained in the energy supply sector.