CCU: Carbon Capture and Utilization

The main problem

The issue is not lack of availability of fossil fuels. The issue is impact of CO2 on climate.

Burning fossil fuels releases too much CO₂, and CO₂ affects climate.

Main options

Option 1: Emit less CO₂ - Companies get a limit/cost for emissions.

EU – ETS (Emissions Trading System). total emission is limited by an emission ceiling (“cap”), the emission allowances are traded on a market

Option 2: CCS - Carbon Capture and Sequestration F.e. Port Of Rotterdam CO2 storage, North Sea

Capturing CO2 immediately after it is formed and storing it, usually
underground in geological reservoirs (storage), to prevent distribution into
the atmosphere.

Option 3: CCU - Carbon Capture and Utilization (CCU) - Instead of storing CO₂:

Capture CO₂ → convert it into useful products. CO₂ conversion requires energy because CO₂ is a low-energy molecule. To make fuel from CO₂ we must add renewable energy. The value of making the fuel is that is stores energy compactly in chemical bonds.

CCS Advantages and Disadvantages

Advantages:

Long - term removal of CO2 from system

Quite mature

Already available for point sources (50%of emission)

Disadvantages:

Cost without benefit

Low social acceptance

Uncertainties on long-term storage

CO2 utilization

• Fuels & chemicals (methanol, methane, urea)

• Food & biological uses (algae, greenhouses)

• Construction materials (carbonates)

• Direct uses (drinks, refrigeration, fire extinguishers)

• Methane has the largest potential for CO₂ utilization.

Technologies for CCU

• Syngas production from CO2 and H2O

CO2 and water are converted into syngas: a mixture of CO and H2, it can be later used to make fuels/chemicals

• Enhanced oil recovery

CO₂ is injected into oil wells to push out more oil. Controversial because it helps produce more fossil fuel (which produce more emissions while burning).

• Dry reforming

CO₂ reacts with methane to produce syngas.

• Methanol synthesis

CO₂ reacts with hydrogen to produce methanol, a fuel/chemical.

• Bioelctrocatalysis

Electricity + microorganisms/catalysts are used to convert CO₂ into useful products.

• Biocatalysis

Microorganisms or enzymes convert CO₂ into products.

• Photocatalysis and artifical photosynthesis

Light/sunlight is used to help convert CO₂ into fuels or chemicals, similar to what plants do.

When chosing a technology, take into account:

• cost

• energy demand

• availability of renewable electricity

• value of the final product

• technology maturity

• actual CO₂ reduction/environmental benefit

Do we have sufficient renewable electricity?

CCU needs huge amounts of renewable electricity:

• Producing hydrogen requires a lot of electricity.

• Converting CO₂ into methanol also requires electricity.

Possible solutions:

• Subsidies

• Stronger ETS (carbon pricing)

• Producing higher-value products from CO₂

• Government regulation and support