Rethinking Emissions Reduction
Renewables and energy efficiency are consistently regarded as the solution to global warming. But a closer look at the state of the global energy system, together with a more refined understanding of the emissions challenge, reveals that carbon capture and storage may well be the critical technology for mitigating climate change.
THE HAGUE – Whether at United Nations climate-change summits or one of the many “green growth” forums, renewables and energy efficiency are consistently regarded as the solution to global warming. Even the coal industry adopted the efficiency line in its Warsaw Communiqué, released ahead of the UN’s COP19 summit last November. But a closer look at the global energy system, together with a more refined understanding of the emissions challenge, reveals that fossil fuels will likely remain dominant throughout this century – meaning that carbon capture and storage (CCS) may well be the critical technology for mitigating climate change.
The widespread focus on efficiency and renewable energy stems from the dissemination of the Kaya Identity, which the Japanese economist Yoichi Kaya developed in 1993. Kaya calculated CO2 emissions by multiplying total population by per capita GDP, energy efficiency (energy use per unit of GDP), and carbon intensity (CO2 per unit of energy). Given the impracticality of winning support for proposals based on population management or limits on individual wealth, analyses using the Kaya Identity tend to bypass the first two terms, leaving energy efficiency and carbon intensity as the most important determinants of total emissions.
But this convenient interpretation does not correspond to reality. The fact is that the rate at which CO2 is being released into the ocean-atmosphere system is several orders of magnitude greater than the rate at which it is returning to geological storage through processes like weathering and ocean sedimentation. In this context, what really matters is the cumulative amount of CO2 being released over time – a fact that the Intergovernmental Panel on Climate Change recognized in its recently released Fifth Assessment Report.