Physical Processes of Carbon Sequestration

Bio-energy with carbon capture and storage (BECCS)

BECCS refers to biomass in power stations and boilers that use carbon capture and storage. The carbon sequestered by the biomass would be captured and stored, thus removing carbon dioxide from the atmosphere.

This technology is sometimes referred to as bio-energy with carbon storage, BECS, though this term can also refer to the carbon sequestration potential in other technologies, such as biochar.

Burial

Burying biomass (such as trees) directly, mimics the natural processes that created fossil fuels. Landfills also represents a physical method of sequestration.

Biochar burial

Biochar is charcoal created by pyrolysis of biomass waste. The resulting material is added to a landfill or used as a soil improver to create terra preta. Biogenic carbon is recycled naturally in the carbon cycle. Pyrolysing it to biochar renders the carbon inert so that it remains sequestered in soil. Further, the soil encourages bulking with new organic matter, which gives additional sequestration benefit.

In the soil, the carbon is unavailable for oxidation to CO₂ and consequential atmospheric release. This is one technique advocated by prominent scientist James Lovelock, creator of the Gaia hypothesis. According to Simon Shackley, "people are talking more about something in the range of one to two billion tonnes a year."

The mechanisms related to biochar are referred to as bio-energy with carbon storage, BECS.

Ocean storage

River mouths bring large quantities of nutrients and dead material from upriver into the ocean as part of the process that eventually produces fossil fuels. Transporting material such as crop waste out to sea and allowing it to sink exploits this idea to increase carbon storage. International regulations on marine dumping may restrict or prevent use of this technique.

Subterranean injection

Carbon dioxide can be injected into depleted oil and gas reservoirs and other geological features, or can be injected into the deep ocean.

The first large-scale CO₂ sequestration project which began in 1996 is called Sleipner, and is located in the North Sea where Norway's StatoilHydro strips carbon dioxide from natural gas with amine solvents and disposed of this carbon dioxide in a deep saline aquifer. In 2000, a coal-fueled synthetic natural gas plant in Beulah, North Dakota, became the world's first coal using plant to capture and store carbon dioxide, at the Weyburn-Midale Carbon Dioxide Project.

CO₂ has been used extensively in enhanced crude oil recovery operations in the United States beginning in 1972. There are in excess of 10,000 wells that inject CO₂ in the state of Texas alone. The gas comes in part from anthropogenic sources, but is principally from large naturally occurring geologic formations of CO₂. It is transported to the oil-producing fields through a large network of over 5,000 kilometres (3,100 mi) of CO₂ pipelines. The use of CO₂ for enhanced oil recovery (EOR) methods in heavy oil reservoirs in the Western Canadian Sedimentary Basin (WCSB) has also been proposed. However, transport cost remains an important hurdle. An extensive CO₂ pipeline system does not yet exist in the WCSB. Athabasca oil sands mining that produces CO₂ is hundreds of kilometers north of the subsurface heavy oil reservoirs that could most benefit from CO₂ injection.