As fracking for shale gas continues to hog the headlines another unconventional mining technology is making waves around the shores of Britain. It’s called underground coal gasification (UCG) and in essence involves burning coal underground to produce gas.
Oil magnate Algy Cluff describes UCG as a “game changer” and believes “it could be a colossal source of energy which could solve our energy needs for decades to come”.
Energy Desk investigates why UCG is emerging, who the major players are and where it is happening. We also highlight the implications of UCG for the local environment as well as associated CO2 emissions.
What?
Underground coal gasification (UCG) is the gasification of coal in situ, underground. It involves the
drilling of two boreholes. The first to injects water and oxygen to partially
combust the coal, producing a mixture of gases (mainly carbon monoxide, carbon
dioxide, methane and hydrogen). These are then extracted to the surface via the
second borehole.
The concoction of gases (termed syngas) has a range of uses. Most simply the gases can be burned to generate electricity. The syngas can also be used to produce plastics or the hydrogen can be separated and extracted.
Courtesy
of sourcewatch.org
According to a director of UCG firm Five-Quarter Energy, Professor Paul Younger: “One of the dumbest things you can with UCG is to burn it [syngas] to produce electricity. The important use of it is as a precursor for plastics and the things modern society relies on. Producing zero emission at point of use fuel such as hydrogen for electric vehicles and fuel cell powered cars is a far smarter thing to do.”
However Clean Coal Limited admits on its website that: “The most likely uses for syngas will be as an energy source for power generation plants” since profitability falls with each stage of refining the syngas.
The UK government has been issuing exploration licences since 2009. The government requires any facility using UCG for power production to use carbon capture and storage (CCS). However a loophole exists, whereby if the gas is used for other purposes (e.g. producing vehicle fuel) then CCS will not be required.
Why?
Advances in horizontal drilling have made drilling cheaper and easier, allowing access to vast areas of coal from a single well. The new technology has brought coal reserves previously too unprofitable or too impractical to mine into play. This, coupled with high energy prices, has made UCG more economically viable (in theory at least).
UCG proponents also argue that the process can cut costs owing from the lack of solid waste and that NOx and SOx produced are trapped underground, preventing acid rain.
How much?
A survey for by the British Geological Survey has estimated that the volume of coal in the UK suitable for UCG is 17 billion tonnes. The BGS say this is sufficient for 289 years, based on current UK coal consumption of 58 megatonnes per year.
Who?
Currently in the UK five companies hold 12 exploratory licences between them: Cluff Natural Resources plc; Europa Oil & Gas Resources Ltd; Five Quarter Energy Ltd; Riverside Energy Ltd and Thornton Energy Ltd.
The licences of Clean Coal Energy Ltd and East Coast Energy Ltd have recently expired, however both firms have reapplied to renew their licences.
Where?
The
map below shows the whereabouts of UK exploratory licences.
UCG was first pioneered in the USSR. Today’s only commercial operation is an old Soviet mine in Uzbekistan which produces 1 million cubic metres of syngas per day. There are a number of small scale demonstration facilities in Turkey, Hungary, South Africa and Australia, aiming to prove the commercial viability of UCG before much larger capital deployment. A growing number of larger projects are in the pipeline, including in Inner Mongolia and a 100MW plant in Alaska aiming to become commercial in 2015.
Environmental concerns?
A major environmental concern with UCG is groundwater contamination. A two year study commissioned by the US Department of Energy found organic toxins (in particular benzene, toluene and phenols) generated during gasification had leached into groundwater. Following a mere 5 days of gasification, phenols were detected up to 30 metres from the burn cavity. The report concluded that residual groundwater contamination some 16 years later was a direct result of UCG.
In 2010 Cougar Energy’s demonstration plant in Australia was shut down after just 5 days when an independent scientific panel detected benzene and toluene in groundwater, as well as in the fat of grazing cattle. Benzene concentrations in groundwater were 45 times the Australian Drinking Water Guidelines.
A second Australian demonstration also backfired. Carbon Energy’s facility at Bloodwood Creek was charged by Australian Department of Environment and Resource Management for a spill of contaminated water pumped up to the surface from the gasification chamber. It later transpired the water, containing benzene and phenol, had been used to irrigate land without approval.
CO2 emissions?
UCG has been hailed as a low carbon technology, with proponents arguing that emitted CO2 can be reinjected back into the mined coal seam and coupled to CCS. However the sluggish development of CCS technology threatens to undermine UCG’s low carbon credentials.
In a review in the journal Nature, Michael Blinderman, director of UCG firm Ergo Exergy Technologies estimated syngas produced by UCG with carbon capture would emit about 380g of CO2 per kWh of electricity produced, roughly 30 times more polluting than onshore wind. However, current government rules only require CCS to implemented in the event that the syngas is used to generate electricity directly and at present implementable CCS technology simply does not exist.
The situation is further complicated by emissions generated from the UCG process itself, which occurs prior to any implementation of CCS technology. According to Grantham Research Institute on Climate Change Professor Michael Jacobs: “If you inject the CO2 into the place where the coal has come from, you only have room for 30% of it.”
He added, “Therefore 70% of the coal emissions would enter the atmosphere, which still makes it more polluting than conventional gas.”
It is therefore unclear whether descriptions of UCG as low carbon technology are really valid.
UCG has been hailed as a low carbon technology, with proponents arguing that emitted CO2 can be reinjected back into the mined coal seam and coupled to CCS. However the sluggish development of CCS technology threatens to undermine UCG’s low carbon credentials.
In a review in the journal Nature, Michael Blinderman, director of UCG firm Ergo Exergy Technologies estimated syngas produced by UCG with carbon capture would emit about 380g of CO2 per kWh of electricity produced, roughly 30 times more polluting than onshore wind. However, current government rules only require CCS to implemented in the event that the syngas is used to generate electricity directly and at present implementable CCS technology simply does not exist.
The situation is further complicated by emissions generated from the UCG process itself, which occurs prior to any implementation of CCS technology. According to Grantham Research Institute on Climate Change Professor Michael Jacobs: “If you inject the CO2 into the place where the coal has come from, you only have room for 30% of it.”
He added, “Therefore 70% of the coal emissions would enter the atmosphere, which still makes it more polluting than conventional gas.”
It is therefore contentious whether descriptions of UCG as a low carbon technology actually stack up.
