Sunday, September 18, 2005

Cost of Artificial Methods

From Wikipedia:

Cost of Carbon Capture and Storage

Capturing and compressing CO2 requires much energy, significantly raising the costs of operation, apart from the added investment costs. It would increase the energy needs of a plant with CCS by about 10-40%. This and other system costs are estimated to increase the costs of energy from a power plant with CCS by 30-60%, depending on the specific circumstances...

...the costs of CCS are dominated by costs of capture. The storage is relatively cheap, geological storage in saline formations or depleted oil or gas fields typically cost 0,5 - 8 US$ per tonne of CO2 injected, plus an additional 0,1 - 0,3 US$ for monitoring costs. However, when storage is combined with Enhanced oil recovery to extract extra oil from an oil field, the storage could yield net benefits of 10 - 16 US$ per tonne of CO2 injected (based on 2003 oil prices). However...the benefits do not outweigh the extra costs of capture.

Friday, September 16, 2005

Artificial Methods of Carbon Sequestration

From Wikipedia:

For carbon to be sequestered artificially (i.e. not using the natural processes of the carbon cycle) it must first be captured. Thereafter it can be stored in a variety of ways.
Natural gas purification plants often already have to remove carbon dioxide, either to avoid dry ice clogging gas tankers or to prevent carbon dioxide concentrations exceeding the 3% maximum permitted on the natural gas distribution grid.

Beyond this, one of the most likely early applications of carbon capture is the capture of carbon dioxide from flue gases at power stations (in the case of coal, this is known as "clean coal"). A typical new 1000-MW coal-fired power station produces around 6m tons of carbon dioxide annually. Adding carbon capture to existing plants can add significantly to the costs of energy production; scrubbing costs aside, a 1000-MW coal plant will require the storage of about 50 million barrels of carbon dioxide a year. However, scrubbing is relatively affordable when added to new plants based on coal gasification technology, where it is estimated to raise energy costs for households in the United States using only coal-fired electricity sources from 10 cents per kWh to 12 [1].

Currently, carbon capture and storage is performed on a large scale by absorption of carbon dioxide onto various amine based solvents. Other techniques are currently being investigated such as pressure and temperature swing absorption, gas separation membranes and cryogenics.

In coal-fired power stations, the main alternatives to retro-fitting amine-based absorbers to existing power stations are two new technologies - coal gasification combined-cycle and oxyfuel combustion. Gasification first produces a "syngas" primarily of hydrogen and carbon monoxide, which is burned, with carbon dioxide filtered from the flue gas. Oxyfuel combustion burns the coal in oxygen instead of air, producing only carbon dioxide and water vapour, which are relatively easily separated. Oxyfuel combustion, however, produces very high temperatures, and the materials to withstand its temperatures are still being developed.
Another long term option is carbon capture directly from the air using hydroxides. The air would literally be scrubbed of its CO2 content. This idea offers an alternative to non-carbon based fuels for the transportation sector.

Another proposed form of carbon sequestration in the ocean is direct injection. In this method, carbon dioxide is pumped directly into the water at depth, and expected to form "lakes" of liquid CO2 at the bottom. Experiments carried out in moderate to deep waters (350 - 3600 meters) indicate that the liquid CO2 reacts to form solid CO2 clathrate hydrates which gradually dissolve in the surrounding waters.

This method, too, has potentially dangerous environmental consequences. The carbon dioxide does react with the water to form carbonic acid, H2CO3; however, most (as much as 99%) remains as dissolved molecular CO2. The equilibrium would no doubt be quite different under the high pressure conditions in the deep ocean. The resulting environmental effects on benthic life forms of the bathypelagic, abyssopelagic and hadopelagic zones are unknown. Even though life appears to be rather sparse in the deep ocean basins, energy and chemical effects in these deep basins could have far reaching implications. Much more work is needed here to define the extent of the potential problems.

It is not clear whether carbon storage in or under oceans is compatible with the London Convention (Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter) [4].
An additional method of long term ocean based sequestration is to gather crop residue such as corn stalks or excess hay into large weighted bales of biomass and deposit it in the alluvial fan areas of the deep ocean basin. Dropping these residues in alluvial fans would cause the residues to be quickly buried in silt on the sea floor, sequestering the biomass for very long time spans. Alluvial fans exist in all of the world's oceans and seas where river deltas fall off the edge of the continental shelf such as the Mississippi alluvial fan in the gulf of Mexico and the Nile alluvial fan in the Mediterranean Sea.

Geological sequestration
Also known as geo-sequestration or geological storage, this method involves injecting carbon dioxide directly into underground geological formations. Declining oil fields, saline aquifers, and unminable coal seams have been suggested as storage sites. Caverns and old mines, that are commonly used to store natural gas are not considered, because of a lack of storage safety.

CO2 has been injected into declining oil fields for more than 30 years, to increase oil recovery. This option is attractive because the storage cost are offset by the sale of additional oil that is recovered. Further benefits are the existing infrastructure, and the geophysical and geological information about the oil field that is available from the oil exploration. All oil fields have a geological barrier preventing upward migration of buoyant fluids (oil in the past, CO2 in the future).

Mineral sequestration
Mineral sequestration aims to trap carbon by placing it in its thermodynamics groundstate where it will be nonreactive. This occurs naturally and is responsible for much of the surface limestone. Acids are used to convert mineral silicates to mineral carbonates. Ongoing research aims to speed up the kinetics of the reactions.

One proposed reaction is that of the rock dunite, or serpentinite with carbon dioxide to form the carbonate mineral magnesite, plus some silica and magnetite. This is proposed by ZECA Corporation, a consortium aiming to produce a low-emission coal-fired power source.

Serpentinite sequestration is favored because of the non-toxic and predictable nature of magnesium carbonate. However, the ideal reaction (reaction 1) takes place only with extremely magnesium rich olivine or serpentine minerals. The presence of iron in the olivine or serpentine will reduce the efficiency of the circuit and reactions 2 and 3 must take place, producing a slag of silica and iron oxide (magnetite).

Serpentinite reactions
Reaction 1Mg-Olivine + Water + Carbon dioxide → Serpentine + Magnesite + Silica

Reaction 2Fe-Olivine + Water + Carbonic acid → Serpentine + Magnetite + Magnesite + Silica

Reaction 3Serpentine + carbon dioxide → Magnesite + silica + water

Tuesday, September 13, 2005

NETL Carbon Sequestration Newsletter Sept 2005

Link Here


Cleveland Plain Dealer, “Coal becoming the hot fuel in
our energy future.

Business Wire, “Syntroleum and Linc Energy Plan to
Integrate Air-Based Fischer-Tropsch Technology with
Underground Coal Gasification.”, “Upcoming carbon management
workshop to focus on activity.”

The Oxford Press (Ohio), “Search is on way to trap
planet-heating carbon dioxide.”

Fuel Processing Technology, Special Issue on CO2
capture and sequestration.

Wall Street Journal, “To Cut Pollution, Dutch Pay a
Dump In Brazil to Clean Up; Kyoto Treaty Creates
Market In Gas-Emission Credits.”

SRiMedia, “Can the oil barons and big power companies
use emission credits from carbon sequestration to
finance clean projects?”

“Errors Cited in Assessing Climate Data.”

“Faster CO2 emissions will overwhelm earth's capacity
to absorb carbon.”

Energy Policy Act of 2005 authorizes suspension ofroyalty payments for CO2 EOR

The Navhind Times (India), “Climate Change Project.”

The Australian, “Safe, cheap storage of CO2 'some way

The Forum (North Dakota), “Non-CO2 technologies
would be the best option

“Designing a Greenhouse Gas Offset System for

Edinburgh Center of Excellence.

Monday, September 12, 2005

Natural Sequestration in Forests and Oceans

From Wikipedia:


Enormous amounts of carbon are naturally stored in the forest by trees and other plants[citation needed], as well as in the forest soil. As part of photosynthesis, plants absorb carbon dioxide from the atmosphere, store the carbon as sugar, starch and cellulose, while oxygen is released back into the atmosphere. A young forest, composed of rapidly growing trees, absorbs carbon dioxide and acts as a sink. Mature forests, made up of a mix of various aged trees as well as dead and decaying matter may be carbon neutral above ground. In the soil however, the gradual buildup of slowly decaying organic material will continue to accumulate carbon thereby acting as a sink.

Oceans are natural carbon dioxide sinks, and as the level of carbon dioxide increases in the atmosphere, the level in the oceans also increases, creating potentially disastrous acidic oceans. Ocean water can hold a variable amount of dissolved CO2 depending on temperature and pressure. Phytoplankton in the oceans, like trees, use photosynthesis to extract carbon from CO2. They are the starting point of the marine food chain. Plankton and other marine organisms extract CO2 from the ocean water to build their skeletons and shells of the mineral calcite, CaCO3. This removes CO2 from the water and more dissolves in from the atmosphere. These calcite skeletons and shells along with the organic carbon of the organism eventually fall to the bottom of the ocean when the organisms die. The carbon or plankton cells have to sink to the deep water in 2000 to 4000 meter to be sequestered for ca. 1000 years. The sinking can be accelerated orders of magnitude when zooplankton prey on the cells and produce fast sinking fecal pellets or fecal strings, like the Antarctic krill. This process is called the biological pump. It has been theorized that the organic carbon within the accumulating ocean bottom sediments is how fossil fuels are created.

Methods of Enhancing natural sequestration

Forests are carbon dioxide stores, but the sink effect exists only when they grow in size: it is thus naturally limited. The rate at which forests can sequester carbon, given the available land, is far exceeded by the rate at which it is released by the combustion of fossilised forests (coal, oil and natural gas). It seems clear that the use of forests to curb climate change can only be a temporary measure. Even optimistic estimates come to the conclusion that the planting of new forests is not enough to counter-balance the current level of greenhouse gas emissions [2]. To reduce U.S. carbon emissions by 7%, as stipulated in the Kyoto Protocol, would require the planting of "an area the size of Texas every 30 years", according to William H. Schlesinger, dean of the Nicholas School of the environment and earth sciences at Duke University, in Durham, N.C. [3].

One of the most promising ways to increase the carbon sequestration efficiency of oceans is to add micrometre-sized iron particles called hematite or iron sulfate to the water. This has the effect of stimulating growth of plankton. Iron is an important nutrient for phytoplankton, usually made available via upwelling along the continental shelves, inflows from rivers and streams, as well as deposition of dust suspended in the atmosphere. Natural sources of ocean iron have been declining in recent decades, contributing to an overall decline in ocean productivity (NASA, 2003). Yet in the presence of iron nutrients plankton populations quickly grow, or 'bloom', expanding the base of biomass productivity throughout the region and removing significant quantities of CO2 from the atmosphere via photosynthesis. A test in 2002 in the Southern Ocean around Antarctica suggests that between 10,000 and 100,000 carbon atoms are sunk for each iron atom added to the water

The carbon sequestration potential of soils (by increasing soil organic matter) is substantial; below ground organic carbon storage is more than twice above-ground storage. Soils' organic carbon levels in many agricultural areas have been severely depleted. Improving the humus levels of these soils would both improve soil quality and increase the amount of carbon sequestered in these soils.

Friday, September 02, 2005

What is Carbon Sequestration?

From Wikipedia:

"Carbon sequestration from a fossil-fuel power station
A carbon dioxide sink or CO2 sink is a carbon reservoir that is increasing in size, and is the opposite of a carbon "source". The main natural sinks are the oceans and growing vegetation. The concept has become more widely known because of its role in the Kyoto Protocol."

"Carbon sequestration is the term describing processes that remove carbon from the atmosphere. A variety of means of artificially capturing and storing carbon, as well as of enhancing natural sequestration processes, are being explored. This is intended to help mitigate global warming."

Types of Carbon Sequestration:

1 Natural sinks
1.1 Forests
1.2 Oceans

2 Enhancing natural sequestration
2.1 Forests
2.2 Oceans
2.3 Soils

3 Artificial sequestration
3.1 Carbon capture
3.2 Oceans
3.3 Geological sequestration
3.4 Mineral sequestration
3.4.1 Serpentinite reactions

Thursday, September 01, 2005

Welcome to Carbon Sequestration Blog

In the past few years, there has been significant discussion of Carbon Sequestration as a technology for removal of carbon dioxide (CO2) from the atmosphere, to reduce global warming. In this blog I'm going to cover that in more detail.

My strategy is simply to start learning everthing there is to know about this new and fascinating technology, and then maybe in a few months start posting conclusions. Hope you find this interesting!