The effective capture rate of carbon dioxide (CO2) at a carbon capture installation at the San Juan Generation Station in New Mexico, USA, is exaggerated, according to analysis from the Institute for Energy Economics and Financial Analysis (IEEFA).

Operator of the unit, Enchant Energy, claims that by retrofitting the plant for carbon capture, 90% or more of the emitted CO2 could be captured. 

Using ‘real-world evidence’, the IEEFA discovered that the effective CO2 capture rate at the plant - after considering the mine’s methane emissions – would be no more than 72%, assuming that the plant captured 95% of generated CO2. 

The study comes following an announcement by the US Department of Energy (DOE) that it will fund six carbon capture demonstration projects. 

Enchant’s proposed project was explored by the IEEFA due to its lack of publicly available data on the production and emissions at both the plant and the mine, in addition to the company’s intention to acquire almost US$1 billion in funding from the federal government. 

With the plant deemed by its owners as ‘no longer economical’ to operate, IEEFA revealed that – even if 90% of the CO2 produced by SJGS is captured – the equivalent (CO2e) capture rate for both the mine and the plant would be just 68%, continuing to emit more than three million tonnes of CO2 equivalents per year. 

In the more likely scenario that Enchant was able to capture only 65% of the CO2, the effective capture rate for both the mine and the plant would be 49%. 

CO2 emission rates could be even higher when considering the potential for leakage during transportation to a storage site and from underground storage facilities.

Roadmap from the Agency for Natural Resources and Energy

Roadmap from the Agency for Natural Resources and Energy

Source: MOL Service

The wider problem with carbon capture

Seen by the International Energy Agency (IEA) as key to achieving Net Zero targets, the study demonstrates that CCS is by no means a perfect solution to climate change.

According to a 2017 UN report, ten billion tonnes of CO2 must be removed per year by 2050 to keep the planet from heating past 2C.

Untreated exhaust from a coal-fired power plant can contain 300 times as much CO2 as the Earth’s atmosphere, which means that - even if CCS could remove 99% of the CO2 from coal plant exhaust - the residual emissions would still have a CO2 concentration equal to or higher than the atmosphere.

A solution suggested by Howard Herzog, a Senior Research Engineer in the MIT Energy Initiative - the Massachussetts Institute for Technology (MIT)’s hub for energy research - focuses on increasing financial incentives for companies to cut carbon emissions.

By taxing plants on whatever CO2 enters the atmosphere, it becomes more affordable for operators to go to higher capture percentages, according to Herzog.

Carbon tax credits like the US 45Q scheme actively encourage companies to capture and reuse their carbon emissions.

Although carbon capture remains a contentious issue, operating costs for CCS can be reduced by advancing and adopting relevant technology, in addition to an increase in support from policymakers.