Introduction

A capture rate above 90% is technically feasible and relatively cost-effective in some cases within the power production sector.  However, in specific areas such as in process industries, this capture rate could imply an excessive cost, potentially due to the large amount of energy required, heat or steam demand, and the complex connections to capture the CO₂ from several CO₂ stacks.

The CO₂StCap project has investigated the techno-economic impact of the CO₂ source (CO₂ concentration, and size), heat supply, and seasonal/hourly variations on CO₂ capture systems integrated in four industries: cement; pulp and paper; steel; and silicon for solar cells.  Based on the results, tailoring the carbon capture system to the specific conditions of the production facility is key to achieving cost-effective systems.

The optimization of a partial CO₂ capture configuration in the industrial sector could be enhanced by assuming potential capture rates that combine low value heat, equipment designed for an average production scenario instead of peak production, and by targeting the most favourable CO₂ sources and / or a specific emissions limit.  If a discontinuous capture scenario is considered, the capture plant could operate when the economic conditions are most favourable, such as when cost variations are beneficial during specific periods during the day/night or seasons.

Key Messages

• For the steel industry, the CO2 capture rates assessed were from 19% to 76.3% of the total plant CO2 emissions, by assuming single or combined CO2 stacks.  The costs are within the range 28-45 €/tonne CO2-captured. The recovery of the available excess heat is key to achieving lower CO2 capture costs.
• For the pulp and paper industry, the CO2 capture rates assessed were from 66.5% to 74% of the total plant CO2 emissions, by assuming combined stacks.  The costs are within the range 41-54 €/tonne CO2-captured.  Capturing CO2 from the lime kiln is more costly than that from the recovery boiler due to the lower volume of CO2 emissions, even though it has a higher CO2 concentration.
• For the cement industry, the CO2 capture rates assessed were from 37% to 90%, all collected in a single stack.  The costs are within the range 50-55 €/tonne CO2-captured.  These values take account of a low capture rate (37%) based on heat recovery from the excess in the production plant, or investing in an additional steam boiler to achieve 90% of capture rate.
• For the silicon industry, the CO2 capture rate assessed was 90% from a single stack.  Due to the small CO2 volume, and low CO2 concentration, the cost of capture is 125-150 €/tonne CO2-captured.
• The size of the CO2 emissions source has the greatest impact on the full capture cost.  This means that the cost of capture will be lower as the source becomes larger.  Moreover, the sensitivity of the capture cost to energy prices is lower in partial capture cases than that in full capture cases.
• The impact of the CO2 capture cost on the final industrial product could be assumed by the end-user, although it will depend on the competitiveness within the sector, profit margins, and the support from funding mechanisms or regulations.
• The use of biomass, hydrogen, renewable energy, and increase of energy efficiency were investigated through a literature review.
• Although the use of biomass appears as an attractive alternative in the literature, limitations on the use of biomass include cost, access and consistency of the original product quality.  A significant substitution of fossil fuels and raw materials by biomass could increase the amount of energy and raw material needed, while changes in equipment and processes would also be needed. Using hydrogen increases the steel production cost (Direct Reduction Iron process, (DRI)) by 20%, and renewables are strongly dependent on the region.
• CO2 utilization was explored through microalgae production in the silicon and cement industries.  The cost of algae cultivation makes this application unfavourable.