Carbon Sequestration Methods: the State of the Art

Daniel “J.” Leistra

GCCS Final Presentation

August 8, 2002

Strategies for Addressing Climate Change

For many, the debate is polarized between mitigation and adaptation

Climate change policies don’t have to be monolithic

Carbon sequestration is the ‘third path’ Sequestration shouldn’t be excluded from any

serious discussion of policy options

Carbon Sequestration: What It Is Stores CO2 removed from the atmosphere or

captured from emissions and stores it in another form somewhere else (a ‘carbon sink’)

Occurs naturally: oceans and plants are already absorbing much of what we emit

We can speed the process along or deposit CO2 in sinks that it wouldn’t have entered before

Possible sinks: plants and soils, carbonate minerals, geologic formations, ocean

Ocean Fertilization Plankton photosynthesis creates

45 Gt organic carbon per year Most carbon gets recycled to

atmosphere, but some is drawn down into deep ocean

Iron is the limiting factor for phytoplankton growth in 20% of the world’s oceans (HNLC zones)

Fertilization with iron could enhance growth, fix more carbon

NOAA/NESDIS SeaWiFS satellite image of 1997 Bering Sea plankton bloom

(http://www.sfos.uaf.edu/npmr/projects)

Studies Show…

Geologic record suggests phytoplankton growth may have substantially decreased atmospheric CO2 in the past

Numerous experiments have shown huge (30-40x) increases in primary production, lower CO2 levels

If it is successful, there will be virtually no limit on how much CO2 the oceans can hold

Problems All of these studies were short-term: unknown how

much CO2 is being carried into the deep ocean Public perception, especially concerning Antarctic

waters Fishing Industry???

Fertilizing every HNLC zone would sequester 76 Gt C by 2100, but would require 300,000 ships and 1.6 billion kg iron annually

Injection into Deep Saline Aquifers Saline aquifers are

underground layers of porous sediment filled with brackish water

If they are deep enough and hydrologically separated from other aquifers, they can safely hold CO2

U.S. is already dumping 75 million cubic meters of industrial waste into deep saline aquifers each year

CO2 injection process is similar to EOR; one commercial venture

The Future is Now

already in place and running smoothly Preliminary geologic data available, compiled by Hovorka et al. (2000)

The Good Deep saline aquifers are widespread: 2/3 of U.S. power

plants and industrial centers could inject without constructing pipelines

Unlike oil and gas fields, they don’t need special geometries to sequester CO2 – wide structures confined only by a horizontal layer of rock can hold it for thousands of years

A large amount of CO2 would be incorporated into rocks and remain stable on a geologic time scale

If there was a natural leak, it wouldn’t pose any danger

The Bad

No incentive to sequester without a carbon tax or a permit system

Injection well failure =

horrible, horrible death

…and the Unknown

Estimates of worldwide sequestration potential range from 320 - 10,000 Gt CO2

Environmentalists and the NIMBY effect More site-specific information needed before

injection can begin

Conclusions

Though no single option is perfect, carbon sequestration has potential for great societal benefits

Continuing research is sure to bring about further breakthroughs, particularly in the field of carbon capture

Climate change policies shouldn’t be all or nothing: while carbon sequestration isn’t the answer, it is an answer

And they all lived happily ever after. THE END

Cropland Retirement 20 – 50% of soil organic

carbon (SOC) lost within first few decades of cultivation

Worldwide estimates of loss = 41 to 55 Gt C

As farms face increasing ecological and economic challenges, many are being abandoned

Cropland Retirement (cont.)

Governments or NGOs can buy back failing farms and attempt to reestablish natural ecosystems

This regeneration can be active or passive Temporary set-asides also a possibility

Predictions

Regenerating forests across eastern U.S. demonstrate that it can work, even without much effort

Removing 15% of land in countries with surpluses would sequester 1.5 – 3 Gt C

Conversion will increase biodiversity, provide habitat for endangered species, protect watersheds, reduce erosion and salinization

Reestablishing grasslands more difficult than forests, but CRP is a well-proven alternative

My Analysis Lower sequestration potential than other options,

but simpler, more environmentally friendly Provides a good way out for struggling farmers,

reduces need for government subsidies Lower food supply helps those farmers that stay in

business, but could hurt the developing world Resulting ecosystems may not be ‘natural,’ but a

managed forest is better than a farm