Pre-Combustion Carbon Capture

The Full Story

Pre-combustion is the process of removing CO2 from fossil fuels before they completely burn. For instance, gasification, the process of heating coal under pressure to produce a synthesis gas, is used. Hydrogen, CO2, carbon monoxide, and a few other smaller substances are present in this gas.

Prior to burning CO2 is taken out of the gasification or reforming process using carbon capture. Next, in an integrated gasification combined cycle (IGCC) power plant, a synthetic gas is produced to either manufacture hydrogen or produce electricity.

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The synthetic gas is transformed to hydrogen and CO2 via the water gas shift reaction (carbon monoxide + water vapor). This carbon dioxide can be collected before it is burned in a gas turbine or used as fuel for a steam methane reformer. Pre-combustion carbon capture can be an effective way to create a stream of CO2 with a better purity since it happens at relatively high pressures. thereby offering a fuel that burns pure and doesn't release CO2.

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The following technologies are frequently employed to recover CO2:

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1. Absorption of solvents (usually amine-based)

2. Chemical and physical adsorbents 

3. Freezing or cryogenic separation

4. separation aided by membranes

The choice of technology will be influenced by various elements, such as:

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1. Ability

2. fuel contaminants

3. Costs of capital and operations

4. Operation and maintenance ease

5. Plot size

For the purpose of producing hydrogen, pre-combustion carbon capture is simply integrated into a steam methane reformer. In IGCC power plants, it is usually more efficient than post-combustion carbon capture.

Pre-combustion capture is frequently more effective but also more costly due to the larger concentrations of hydrocarbons present prior to combustion. This is because capturing necessitates additional steps. Its capabilities are not as well-tested as they could be because retrofitting older buildings with this technology is not yet cost-effective.