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Clean coal, the message returned with warm regards to sender

David Hallowes is a researcher at groundWork, an environmental justice organisation.

The Department of Mineral Resources and Energy has urged companies to invest in ‘clean coal’, but ‘clean coal’ technologies are expensive, add to the enormous resource consumption of coal-fired generation, and either don’t work or make little difference to the harm done to health and the environment.

The business end of the coal lobby met at the Southern African Coal Conference in Cape Town last week. Thabo Mokoena of the Department of Mineral Resources and Energy was with them and, as expected, urged companies to invest in “clean coal”. This is a message that the coal lobby is pleased to hear since it came from them in the first place. And it is repeated in the department’s 2019 Integrated Resource Plan (IRP) for electricity, published in October, a document that defies rationality in its determination to keep coal on the road. 

At the IRP’s core are a number of decisions, the most startling of which is “Decision 3” which says that Eskom should be allowed to break the law: “Shutting down of MES non-compliant power plants” is “not recommended”. MES are minimum emission standards, mandated by the Air Quality Act of 2004, which put a legal limit on how much sulphur, nitrogen and particulate pollution a plant may put into the air. 

Apart from being dirty, coal is costly. The IRP is based on modelling that selects technologies to create the “least cost” future power system. Since about 2014, renewables have been cheaper than new coal. The IRP 2019 therefore has to “force” 1,500MW of new coal-fired power into the plan of what to build between now and 2030. That dirty power will add something like R45-billion to the cost of the system by 2050.

Beyond 2030, however, the department seems to envisage burning coal into the next century. Never mind the climate crisis. According to Decision 6: “South Africa should not sterilise the development of its coal resources for purposes of power generation, instead all new coal power projects must be based on high efficiency, low emission technologies [HELE] and other cleaner coal technologies”. This does not apply to the 1,500MW to be built before 2030. 

The IRP says, “HELE coal technologies including underground coal gasification, integrated gasification combined cycle, carbon capture utilisation and storage, ultra-supercritical, super-critical and similar technologies are preferred for the exploitation of our coal resources”. Unfortunately, these “clean coal” technologies are even more expensive, add to the enormous resource consumption of coal-fired generation, and either don’t work or make little difference to the harm done to health and the environment. 

Flue gas desulphurisation (FGD), a standard technology that actually does work in reducing health impacts, is not mentioned in this list. This is what is needed to make Eskom comply with the MES for sulphur dioxide but Eskom says it is too costly. It is to be installed at Kusile and Medupi, but the IRP shows no plan to install FGD at any of the other 13 plants. Decision 3, says government, will “support Eskom to comply with MES over time” but, it seems, not with the MES for sulphur dioxide.

FGD is an expensive but standard technology. Carbon capture and storage (CCS) barely exists. There are only 19 working carbon capture projects around the world, most of them capturing carbon from produced gas at oil wells. Only four actually aim to store it underground forever and, all told, they have buried a grand total of about 33 million tonnes (Mt). Most of the rest is used for enhanced oil recovery (EOR) – they pump the CO2 into an oil well to restore the pressure and so extract more oil. About half the CO2 comes back up with the oil. And the well produces more oil which, of course, is destined to be burnt. 

There are two coal power stations in the world with carbon capture plants. The plant at SaskPower’s Boundary Dam in Canada captures CO2 from one of four units. It was over budget, over time and doesn’t work very well. It has captured about half the CO2 emitted from that unit and consumed about a third of the energy produced by it. The CO2 is sold for EOR to a neighbouring oil company. Otherwise, says SaskPower, the plant would not be economic. Not, as it turns out, that it is economic. Following “its costly experience”, comments David Schlissel of the Institute for Energy Economics and Financial Analysis (IEEFA), the company has decided “against retrofitting two other units at Boundary Dam with carbon capture technology”. 

Integrated Gasification Combined Cycle (IGCC) has also been beset by failure. As described by energy journalist David Wagman, it consists of a conventional “natural” gas combined cycle power station with a “chemistry set bolted onto it… to strip out methane from coal” and supply it to the power plant. As with CCS, about a third of the energy generated by the gas plant is used to run the coal gasifiers (the chemistry set) but the process is meant to separate the carbon before combustion and so enable CCS. 

The Kemper power plant in Mississippi, US, was to be the flagship for this technology. The gas power station was completed on time in 2014 and started running on fossil gas that was then being produced by fracking. The gasification plant failed to achieve successive milestones, was way over budget and was finally abandoned in 2017. Even if it had worked, Schlissel notes that it would have been less efficient than a conventional gas plant and would have cost a lot more in maintenance. Further, the plant consumed massive quantities of water and much more than anticipated. 

High water consumption is a common feature of all CCS plants, “affecting all stages of the process – from cooling the plant to capturing, compressing and injecting the captured CO2”, and would double a coal plant’s water consumption. “For coal facilities in arid regions this is obviously a deal-breaker,” comments Schlissel. 

Another problem is where to put it. It can be injected into specific geological formations but, if it is done on the scale required, there is no certainty that it will not leak out. In South Africa, two potential storage sites have been identified – offshore of KwaZulu-Natal and offshore of the Eastern Cape. A vast network of pipelines would be needed to carry compressed CO2 from the Highveld and Waterberg to these sites.

Supercritical and ultra-supercritical plants are more efficient than subcritical plants. New subcritical plants should convert about 38% of the energy in coal into electricity. Eskom’s plants get less than 35%. Supercritical plants, such as Medupi and Kusile, should convert around 42% – if they work – and ultra-supercritical plants convert up to 45%. Put another way, ultra-supercritical plants get about 14% more energy out of every tonne of coal burnt. But burning a tonne of coal still produces the same amount of pollution. Taking out the sulphur, nitrogen and particulate pollution requires the same FGD scrubbers and baghouses irrespective of whether the plant is super or subcritical. 

Before coal can be burnt, it must be mined and all coal mining is dirty. It destroys good land, uses lots of water and pollutes more, fills the air with dust from trucks and blasting, and leaves behind massive discard coal heaps which frequently catch fire. Further, the latest World Energy Outlook from the International Energy Agency (IEA) shows massive methane leakage from mines. Methane is a potent greenhouse gas and the IEA puts the leakage from South African mines at 50 Mt/CO2e a year. That makes a significant addition to the national greenhouse gas count. 

Eskom, like the IRP, claims that underground coal gasification (UCG) is an “advanced clean coal technology” because it substitutes for mining and the gas is supposed to burn cleaner than coal at the power plant. UCG works by drilling two sets of holes into a coal seam, blowing oxygen into one side, setting fire to the coal underground, and extracting gas the other side. 

There are two big problems with this story. First, UCG is only used where coal is unmineable. So it does not reduce emissions, it expands the resource. As Eskom puts it, “Almost three-quarters of the country’s coal resources are presently regarded as conventionally unmineable, but could be extracted using UCG technology.” That could add up to 160 billion tonnes of additional carbon emissions. Eskom’s favoured technology combines UCG with IGCC. For carbon emissions, the results are not very impressive. Eskom cites an IEA clean coal report showing the following emission factors for various fossil fuel power stations (CO2 kg/MWh)

    1. Conventional coal: 950
    2. Supercritical coal: 850
    3. Conventional IGCC: 750
    4. UGC-IGCC: 700
    5. Natural Gas CC: 450

Eskom’s own coal-fired emission factor is 1,040 CO2 kg/MWh. Total life cycle emissions – including emissions from mining and transport of coal, power plant materials, construction and demolition and other processes – would bump that number up to 1,170kg or more. In contrast, lifecycle emissions from wind are between 14 and 21 CO2 kg/MWh.

Second, the underground fire burns at 1,200˚C, leaving a burnt-out cavity, collapsing the ground and rock layers above it, and polluting groundwater. In addition, “wastewater’ saturated with hydrocarbons, metals and salts also comes up with the gas through the extraction well. It is collected in a series of evaporation ponds and liable to spill out into surface water. 

In Australia, three UCG projects have all ended with charges laid against the companies for groundwater pollution. In the case of Linc Energy, the supposed industry leader, methane gas from the cavity saturated the ground above. The government told farmers not to dig any holes deeper than 2m in an “excavation exclusion zone” covering 314 square kilometres. Kat Moore of Friends of the Earth Australia reported that workers suffered “heart palpitations, stinging eyes and headaches, and sometimes had to drive a number of kilometres off-site before their personal gas detector would stop registering”.

In South Africa, Eskom has a UCG project at Majuba where the coal proved unmineable. It initially hoped to provide 30% of the power station’s energy (equivalent to 4.5Mt of coal a year). The coal seam was lit in January 2007 and, in 2014, Eskom said that the “first pilot” was producing 15,000m3 of gas per hour. It was intended that this would be ramped up to 75,000m3 an hour to co-power one of Majuba’s six units. However, the initial test firing in 2014 was very brief – scarcely an hour on one account – and the rest of the gas was flared. In its 2015 Integrated Report, Eskom reported a R1.05-billion impairment on the UCG project and the site was all but abandoned.

The minister, Gwede Mantashe, has several times denied that he is a coal fundamentalist. Indeed, he has denied it more often than he has been called it and, at the coal conference, Mokoena repeated that denial on his behalf. Rather, the minister and the IRP had adopted a “balanced approach”. The minister would also no doubt deny being a climate denialist. But that is what is coded into the rhetoric of clean coal. It is not really about unlikely investments in speculative technologies. It is about justifying new coal projects now. As to balance, it will be swept away in the storms of the climate crisis. DM


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