As climate and energy policy continues to evolve, the EPA recently released a new proposed rule for environmental standards regarding emissions from coal and natural gas-fired power plants. An integral part of the proposal is reducing CO2 emissions through a process called carbon capture. First used as early as 1972, carbon capture refers to technology that captures carbon dioxide emissions from either industrial plants or power plants that burn fossil fuels.
There are three major methods of carbon capture: post-combustion, pre-combustion, and oxy-fuel combustion. For post-combustion, a chemical solvent is used to separate the CO2 from the flue gas stream created by the burning of fossil fuels. During pre-combustion carbon capture, fuel is converted into a mixture of hydrogen and carbon dioxide. The CO2 is then separated, and the remaining portion is burned as fuel. Lastly, oxy-fuel carbon capture is when fuel is burned in pure oxygen, resulting in the release of CO2 and steam from which the carbon dioxide can be transported and stored.
Just like most other forms of emission-reducing technology, carbon capture has its own costs. These costs vary depending on what processes it is being used for as well as scale. The greatest contributing factor to the cost of carbon capture is the concentration of the CO2 – more concentrated carbon dioxide is often cheaper to capture, while less concentrated carbon is more expensive. When it comes to the power generation sector targeted by the new EPA proposal, the low-concentration carbon dioxide costs from $50 to $100 per metric ton of CO2. Carbon capture in industrial processes such as iron and steel production face similar costs of $40 to $100 per metric ton, while others such as ammonia production for use in fertilizers cost $25 to $35 per metric ton and is likely the cheapest option for abatement in this sector. Below is a further breakdown of costs by sector:
It is important to remember that the cost of using carbon capture technology is not the only cost of capturing the carbon. The captured carbon must also be transported and stored (or used). This is most commonly done through an onshore pipeline system that transports the carbon to underground reservoirs, but offshore transportation and storage are also possible. A 2021 study from the International Journal of Greenhouse Gas Control found that onshore transport and storage cost $4 to $45 per ton of CO2, while offshore transport and storage can cost between $35 and $64 per ton of CO2.
Considering that in 2021, over 1.5 billion metric tons of carbon dioxide was emitted in the US from power generation alone, there are certainly major costs associated with significantly increasing the usage of carbon capture and storage technologies.
This leads us to ask, what kind of benefits are we getting from this technology? It has been that carbon capture effectively captures 90 percent of the carbon emitted from a plant. However, a 2019 study from the journal “Energy and Environmental Science” examines the W.A. Parish coal power plant, a facility retrofitted with carbon capture technology in 2017. It finds that the equipment captures an average of 55.4 percent of CO2 as opposed to the commonly cited 90 percent. Furthermore, the carbon capture technology at this location is powered by natural gas, which has its own emissions – bringing down the net reduction in carbon dioxide emissions to only 10.5 percent averaged over 20 years. They also note that carbon capture fails to capture other harmful emissions, such as mercury, nitrogen oxides, toxins and more.
However, it is important to consider alternatives to achieving lower levels of CO2 emissions. Carbon capture has the distinct advantage of being applied to existing power plants and industrial plants, as was first done by Canada’s SaskPower in 2014 with the Boundary Dam Power Station. This means that the technology allows us to reduce emissions without having to decommission current facilities – a strength that cannot be understated. When it comes to long-term goals of reducing emissions, being able to retrofit existing facilities with carbon capture technology allows for greater use of current infrastructure and industry than many of its alternatives. But these alternatives, such as solar and wind energy, produce zero emissions, CO2 or otherwise, during electricity production.
Thinking back to the recent EPA proposal, regardless of its viability, carbon capture is crucial to keep in mind in discussions about an environmentally friendly economy in a variety of sectors. But its costs and benefits must be weighed objectively. While the emissions reductions don’t match those of renewable energy sources in its current form, carbon capture has its own unique benefits and likely will continue to be improved upon going forward.
Written by Andrew Barton, Public Policy Intern
The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization. An innovative think tank, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, energy, infrastructure, innovation, technology, and transportation.