The US Department of Energy (DoE) first started sponsoring clean coal technology back in the late 1990s, and more than $7.5bn of the federal budget has been allocated to supporting its development since 2008. To date, not a single commercial-scale carbon capture and sequestration (CCS) power plant has been brought online in the US, and the Texas Clean Energy Project (TCEP) is the latest CCS project in the growing list of stalled and abandoned initiatives, both in the US and around the world.

Hailed as coal-fired generation for the 21st century, ‘clean coal’ technologies such as the integrated gasification combined cycle (IGCC) with carbon capture approaches, planned for both the Texas and Kemper County plants seemed so promising. Turn coal into a clean-burning synthetic gas, the reasoning goes, strip out the pollutants and impurities before burning it to produce electricity, with heat recovery to maximise generation efficiency, then sequester 60% or more of the CO2 produced and the environmental downside of coal can be significantly mitigated.

With coal estimated to be responsible for 45% of the emissions implicated in climate change, and over a quarter of the world’s electricity being generated in plants that burn it, the appeal of clean coal is obvious, and its potential global benefit correspondingly enormous. According to United Nations studies from the mid-2000s, CCS may have a bigger impact on reducing greenhouse gas emissions throughout the century than a shift to renewable sources, such as wind or solar power.

Muddled debate on clean coal

Making that happen, however, was never destined to be cheap or easy. Contemporary estimates from the International Energy Agency (IEA) put the anticipated investment required for 2010-2020 at $56bn, a further $646bn over the next ten years to 2030, and annual costs perhaps topping $350bn by mid-century. In October 2009, Nobuo Tanaka, the then IEA Executive Director, told the Carbon Sequestration Leadership Forum, that the world would need 100 large-scale CCS projects by 2020, 850 by 2030 and 3,400 in 2050.

Today, just seven years later, the prospect of achieving anything even remotely like those sorts of numbers seems a distant dream, leaving some important questions hanging over the future of clean coal. Despite the setbacks, is it a technically feasible solution that will eventually be made economically viable, or is it simply a case of too little and too late – a costly pipe dream that has run out of time?

“The carbon capture debate often muddles together three conversations about hurdles to scaling up carbon capture – political, economic, and technical potential,” says Kyle Ash, Washington-based senior legislative representative for Greenpeace USA. “These three issues are interrelated, but almost nobody thinks CCS can easily overcome all three barriers.”

"American Electric Power’s Mountaineer plant in West Virginia, successfully captured and stored more than 37,000t of CO2 between 2009 and 2011."

There is little doubt that the clean coal concept is technically achievable. There have been a number of well-documented demonstration projects, including American Electric Power’s Mountaineer plant in West Virginia, which successfully captured and stored more than 37,000t of CO2 between 2009 and 2011, and CCS itself has had its successes on a larger scale too. For the past two decades, Norway’s Statoil company has been successfully injecting CO2 into the void-space of the Sleipner gas field in the North Sea, at a rate of around one million tonnes a year. Proponents say this proves that full-scale carbon sequestration can work, but the argument side-steps one of the fundamental criticisms that is always levelled against clean coal – the cost.

Carbon capture: A fiscal travesty?

For Statoil, the origin of the CO2 as part of the natural gas mix rather than a combustion product, coupled with Norwegian regulation and tax treatment of sequestration as opposed to disposal, makes its approach economically viable, as well as environmentally desirable. For coal-fired power stations, the balance sheet says otherwise, and ultimately, clean coal’s critics say the economic and political considerations are the key drivers, rather than technical ones.

According to Ash, the DOE’s financial projections for the levelized cost of new energy sources show that carbon capture would be the most expensive way to avoid CO2 emissions, per unit of electricity, even in highly efficient coal plants.

“TCEP and Kemper are standard bearers for the fiscal travesty that subsidised carbon capture projects exact on American tax – and rate-payers,” he says.

Nevertheless, while IGCC-with-CCS coal plants may be the most expensive means of carbon mitigation on a kW for kW basis, the fact remains that coal-fired generation produces a lot of electricity, predictably and reliably, irrespective of whether the wind blows, or the sun shines.

There are those who argue that, between the inherent intermittency of wind and solar power and the current limitations of storage solutions, the world needs to develop a portfolio of low-carbon energy options, which includes methods such as carbon capture and clean coal technologies.

Howard Herzog is one proponent. A senior research engineer on the Massachusetts Institute of Technology’s Energy Initiative, he made his thoughts clear in the New York Times in July, when news of Kemper’s budgetary and scheduling over-runs re-ignited public debate over the future of the technology.

"'Arguing that renewables can do it alone is a very risky proposition' says Howard Herzog."

“The magnitude of the climate challenge is so large, we need as many options as possible, including renewables, nuclear and carbon capture. But arguing that renewables can do it alone is a very risky proposition,” he wrote.

Ash, however, worries that viewing clean coal as a necessary stop-gap option, whether driven by doubts over the technical and economic promise of the 100% renewable ideal, or the political willingness to support it, risks boosting the wider case for fossil fuels. He adds that pro-climate politicians wrongly believe that entertaining CCS will bring fossil-friendly colleagues to the negotiating table.

“There is plenty of evidence that this pro-coal PR actually emboldens the industry and forestalls politicians, such as those from West Virginia and Kentucky, from accepting that coal’s days are numbered,” Ash says.

A pork project

The biggest driver today comes not from the coal industry, says Ash, but from oil where the CO2 from carbon capture would be a valuable asset to help increase production as part of the sector’s expansion strategy. He points to moves made by Texas Republican Congressman Conaway to support TCEP by tripling and making permanent the 45Q Tax Credit for carbon capture for enhanced oil recovery – something he describes as “nothing but a pork project” for the oil industry.

“That Conaway has partially succeeded in putting a green stamp on his very anti-climate legislative proposal is a testament to ignorance on Capitol Hill that the impetus behind carbon capture policy is growing oil production, not reducing climate pollution,” Ash says.

Having survived sustained warnings throughout 2015 that the world’s coal reserves should almost entirely be left in the ground to hit the 2°C globally agreed target, once again the death of clean coal has perhaps been announced a little prematurely.

It seems the ‘lost cause’ is not quite so lost, at least not just yet.