Carbon Capture and Storage (CCS) is an environmental technology which enables large point sources of CO2, such as power plants or industrial facilities, to significantly lower their emissions while still using or storing captured CO2. Captured CO2 can either be reused for other purposes or stored permanently underground in geological formations.
CO2 captured from sources is compressed and transported via pipelines or ships to storage sites for injection into deep underground geological formations, such as depleted oil and gas reservoirs or saline aquifers.
Enhanced Oil Recovery
Enhancement oil recovery (EOR) is the process of increasing oil reservoir production after primary and secondary recovery techniques have exhausted themselves. Different techniques, such as fire flooding, water alternating gas injection, polymer flooding and polymer flooding; solvents like CO2 or foam; flow diversion with surfactants are employed as EOR techniques.
CO2-EOR (CO2 Injection), which is a third-stage recovery technique, involves injecting carbon dioxide into an oil reservoir in order to decrease viscosity and expand it, thus freeing oil from formation and increasing flow to wells. CO2-EOR can increase reserves by as much as one percent.
CO2-EOR technology does not directly address climate change unless combined with geological carbon storage; however, recent investment commitments indicate it could soon become a breakthrough solution. Carbon capture from power plants must then be transported via pipeline to oil reservoirs for storage.
Biofuels
Biofuels are liquid or gaseous fuels produced from plant, animal and food waste materials that can be used as replacement fuels for transportation vehicles like gasoline and diesel. Not only do biofuels reduce greenhouse gas emissions while remaining renewable resources may even be locally sourced making them a more sustainable solution than their fossil counterparts.
Ethanol from corn is the most prevalent liquid biofuel, accounting for an estimated 86% of U.S. production and consumption in 2021. Many countries, however, are actively exploring other more advanced biofuel options that could replace gasoline in light vehicles as well as energy applications.
CCS/CCU can significantly enhance biofuel production without compromising other performance indicators such as GHG emission reductions and economic efficiency. Dilute CO2 streams originating from combustion or steam-methane reforming applications generally dominate biofuel carbon balances in all pathways except drop-in biofuels made of lignin (DrLiHd) and tall oil (DrToHd), and CCS/CCU may help address their deficiencies – producing concentrated streams which are then typically used for process heating or converted into bio-methane (MeFmAd, MeSsAd, MeBaGm). Depending on their pathway this may enhance CCU performance further.
Chemicals
Chemicals are composed of molecules arranged like LEGO bricks. These substances can take the form of liquid, solid, or gas and include common examples like water, diamonds, and table salt. Chemicals may either be pure – with identical atoms throughout – or mixed forms may exist as well.
Most large scale CCS projects use post-combustion processes to isolate carbon dioxide from other gases produced during fossil fuel combustion, typically nitrogen and hydrogen. Chemical solvents may also be used as part of this separation process.
CO2 captured through CCS systems is then transported via pipelines to an underground storage site for permanent storage, such as those used by Snohvit or depleted oil and gas reservoirs or basalt formations. Once there, it may be injected into porous rock formations deep underground for permanent storing purposes – also referred to as geologic carbon storage sites; impurities present may hinder how efficiently CO2 is stored underground. Impurities present further complicate matters in CCS systems as they could interfere with how effectively CO2 is stored underground permanently compared with how efficiently CO2 itself is stored underground compared with how effectively CO2 itself is stored underground compared with how effectively its stored CO2.
Energy
Carbon capture technology is already employed at power plants powered by coal or natural gas, cement factories, steel mills, and petrochemical facilities – yet to effectively combat climate change, it will need to expand to capture and store CO2 from other energy sources as well.
CCS isn’t a silver bullet for emissions reduction, but it can assist other technologies in decarbonising sectors such as power generation and heavy industry. At present, thirty CCS projects exist around the globe.
These projects mainly aim at producing hydrogen from natural gas with carbon capture, then transporting that to consumers for zero-emission power, fuels or materials. Other projects focus on capturing CO2 from blast furnace exhaust at fossil fuel-powered plants and storing it in deep saline formations like oil fields or coal beds too deep to mine economically – the NRG Petra Nova project in Texas being an example. Unfortunately these projects often operate less than expected because plant operators reduce electricity output or CO2 demand to maximize profits.