8 - Carbon dioxide capture and sequestration

Summary

Focus

A transition to a low-carbon economy can be facilitated by CO₂ capture and sequestration. This chapter focuses on capture of carbon dioxide from industrial emission sources such as electricity generation and sequestration in deep geological formations. A detailed description of the technology is provided, including the potential scale of application, estimated costs, assessment of risks, and emerging research issues.

Synopsis

Today, 60% of global CO₂ emissions come from large point sources such as power plants, refineries, cement plants, and steel mills. Reducing emissions from these sources will require reducing demand for the services or materials they provide, finding alternative ways to provide similar services with lower carbon dioxide emissions, or directly reducing emissions by capturing and sequestering emissions. Technology to capture carbon dioxide is available today, but capturing and sequestering CO₂ will increase the cost of electricity production by an estimated 50%–100% compared with today's generating costs. Moreover, an estimated increase of 15%–30% of the primary energy supply needed to deliver these services or goods would be required. Captured carbon dioxide can be sequestered in deep geological formations, either onshore or offshore. Sedimentary basins are the preferred location for carbon dioxide sequestration, since they are known to contain both the porous and permeable sandstone formations needed to sequester CO₂ and low-permeability rocks such as shale that can trap CO₂ for geological time periods of millions of years. The estimated capacity for sequestering CO₂ is large and expected to be sufficient for at least 100 years of needed demand. However, the actual capacity for safe and environmentally benign sequestration remains uncertain, since CO₂ sequestration has been employed for little more than a decade and only on a small scale. Nevertheless, the basic technologies for sequestration and performance prediction are mature, building on nearly a century of oil and gas production, natural-gas storage, CO₂-enhanced oil recovery (CO₂-EOR), and acid gas disposal. Enhancements of these technologies will arise as geological sequestration itself matures – but they are sufficiently developed to initiate sequestration today. Regulatory and legal issues remain to be resolved, including issues such as permits for sequestration-project siting, well drilling, and completion, operational parameters such as maximum injection pressures, ownership of underground power space, supremacy of mineral or groundwater rights, and liability for long-term stewardship. Resolving these issues and gaining support for this approach from the public are likely to be the greatest challenges for implementing CO₂ capture and sequestration on a meaningful scale.