All out of gas

Materials World magazine
4 Dec 2011

An alternative source of fuel should have the energy industry dancing in tandem but the environmental implications of shale gas have left it dispersed, with each sector determined on fighting its own corner. Ledetta Asfa-Wossen reports on the Environmental Gas Summit 2011

The Chairman’s apologies for a truncated coffee break due to anti-fracking demonstrations was met with restless growls akin to apes at the height of mating season.

The first shale gas well was drilled in Fredonia, New York in 1821, and although the UK is considered a newcomer to the source, its first well was drilled back in 1875 – albeit accidentally, by a group of geologists for academic enlightenment. However, the well and associated oil was of no interest and a cap was promptly placed. More than a century later, with the exception of Cuadrilla’s recent exploration, the UK is yet to commence any sizeable production.

The first speaker up in the box was pro-shale Director Benny Peiser, of the Global Warming Policy Foundation, UK. Peiser spoke of an energy revolution and the impact shale gas could have on UK and EU climate policy. He shot down any concerns from Government that an alternative gas could undermine the renewables market and said that shale would help end the electricity crisis and lead to an affordable resource in decarbonisation. ‘We’re not here to talk about electricity', exclaimed a commodity consultant at the front, exasperated by Peiser’s win-win argument. But, if 90% of the UK’s electricity is generated from coal, gas and nuclear, to fully consider the benefits of shale gas, all fuels in the energy mix have to be considered.

On the road to low CO2?

So, aside from its commercial value what is the benefit of shale gas? John Baldwin of CNG Services Ltd argued that it could have a transformational impact on the road fuel market to meet rising oil demands. ‘DECC forecasts that by 2020, the UK will be importing around one million bbls of oil per day, almost all for road transport. How can we afford this?’

Highlighting how shale could become a crucial source to meet energy needs, Baldwin added, ‘Nuclear stations are closing down and we may not build new ones. Coal plants too. Carbon capture storage (CCS) may not be viable. So, electricity will come from gas with some nuclear and some coal with CCS and a lot of wind (when it’s windy). Transport will be diesel-petrol with electricity (i.e gas). Heating will be gas. There are no realistic alternatives to lots of gas-fired combined cycle gas turbines (CCGTs)’.

One example of how shale gas can assist the UK’s ambitious carbon emission targets is through dual fuel trucks, using a dieselfossil CNG tractor. Baldwin explained, ‘These vehicles can be transformational – they have the benefit of diesel efficiency but with natural gas and lower CO2. With the world full of shale gas we can now start to shift trucks to dual fuel CNG diesel. There are no material issues with shale gas; it’s a very low CO2 fuel compared to LNG. This will save the UK market the cost of imports so the money can be invested in renewables such as offshore wind.’

The facts

Shale gas is formed from organic matter (kerogen) in shale rock either by heat (thermal maturation) or more rarely by bacterial action (methanogenic maturation). Unlike petroleum oil extraction, there are pitfalls to shale gas extraction.

Shale has a low matrix permeability, so gas production in commercial quantities requires fractures to provide permeability. Horizontal drilling is often used with shale gas wells, with lateral lengths up to 10,000ft (3,000m) within the shale, to create maximum borehole surface area in contact with the shale.

Shales that host economic quantities of gas have a number of common properties. They are rich in organic material (0.5% to 25%), and are usually mature petroleum source rocks in the thermogenic gas window, where high heat and pressure have converted petroleum to natural gas. They are sufficiently brittle and rigid enough to maintain open fractures.

Some of the gas produced is held in natural fractures, some in pore spaces, and some is adsorbed onto the organic material. The gas in the fractures is produced immediately; the gas is adsorbed onto organic material and is released as the formation pressure is drawn down by the well.

No fracking please, we’re British

Tony Grayling of the UK’s Environment Agency (EA) discussed the potential environmental damage from shale gas exploration. Of primary concern were the risks to air and water from fracking, such as fugitive emissions of methane, impact on water resources from water used in hydraulic fracturing, contamination of groundwater due to poor well design or failure and contamination of groundwater due to mobilisation of solutes or methane.

In terms of post-production, Grayling remarked that inadequate transport or treatment of wastewater and contamination of soil, due to spills of chemicals or return fluids needed to be tackled too.

A more pertinent issue has been the risk of blowout and casing failure and fugitive emissions from the fracking zone. However, Grayling noted that the fracking process may not be as alarming as NGO’s make out.

‘There are significant risks to the environment from shale gas, as in any industrial process. These risks can, however, be successfully managed through effective regulation. To ensure effective controls and development public involvement is key’.

On a ground level, the small earthquake (2.3 on the Richter scale) near Cuadrilla’s drilling site in Blackpool have caused the most fear. Two reports on the drilling area have since been completed, but a more recent independent report, commissioned by the company, states that the tremors were not only caused by injecting fluids under high pressure deep underground to deliberately blast apart the gas-bearing rock but by pre-existing geological factors.

A Green Party representative for Lancashire voiced that residents in the area were unsettled by the tremors and the possibility of methane leaking into local drinking water. However, Emeritus Professor of Petroleum and Geology at Imperial College, London, UK, Richard Selley argued that a post-millennial US shale gas renaissance has meant extraction methods have significantly improved due to improved horizontal drilling technology, hydraulic fracture technology and seismic imaging.

Peers for fears

Mike Stephenson, a BGS geologist put the debate in perspective and called for attendees to ‘distinguish between what matters and what doesn’t, then regulate and control. Much of the risk is known and understood and manageable e.g. gas wells by the oil and gas industry’. He continued, ‘Some [risks] however are not known, baseline amounts of methane in groundwater for one. The composition of flowback water. Long-term effects of fracking chemicals in shale. And, the migration of methane in natural and induced fractures.’

Stephenson noted that the only way forward is through more peer-reviewed science and risk-assessment. He remarked that there were not enough papers released on shale extraction and what is available is often equivocal. Some papers he cited as examples of well-peered papers included a US study into ‘Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing’, that revealed the average 13C-CH4 values of dissolved methane in shallow groundwater was lower in gas drilling areas than in other areas (-37% and -54% respectively).

Another hindrance to the issue is that many of the peer-reviewed articles on extraction have been written in shale extracting regions outside the UK, such as the US, Poland and China. The varied geological landscapes mean these papers are limited.

No fracking way

Senior Policy Officer Dan Benton of the Green Alliance stated that even if shale gas did become a strategy for action in the UK, ‘we’re likely to get less shale gas than promoters suggest because of public concern with environment protection’.

Citing Pennsylvania as an example, Benton illustrated the short- and long term impact caused to land by lorry movements alone, where a well was located every 40 acres. Another stalling factor, said Benton, would not only be the restrictions on national parks and areas of outstanding beauty but also the social demographic of the area. He noted that many of the regions marking potential are in the 10% most wealthy bracket and may as well be discounted from shale gas plans.

Bridge or destination fuel?

Another concern Benton has is that a second dash for gas won’t cut carbon emissions enough. He notes that the only way to avoid a ‘gas-lock-in’ and sustain reserves is through CCS and by locating CCGTs and industrial emitters to reduce the cost of CCS. He adds, ‘Heating wil require gas for longer, however this shale gas is only a medium source of demand. Efficiency and heat pumps will need to reduce demand steadily from 2020s onward. Without CCS a gas has a very limited future.’

On the topic of shale’s role in Climate Change, Professer Kevin Anderson said ‘through a stringent and appropriate regulatory and monitoring regime, the environmental implications of shale gas extraction could be brought to levels similar to those acceptable with regards to the extraction of natural gas. However, climate change is a different story.’

From a relative emissions perspective gas is better than coal, even if there are relatively high emissions from producing and transporting shale gas, explained Anderson. Combustion via a CCGT is 15-20% more efficient than a good coal station and has lower combustion emissions than coal or oil for the same energy output. But the climate does not care about efficiency or relative emissions it only responds to total emissions of GHGs.

He argued to meet the Copenhagen Accord (2009) commitment we must hold the increase in global temperature below 2ºC.

Anderson concluded that, while shale gas could act as a substitute for coal, the UK should guard against shale gas substitution for genuine low and zero carbon energy sources. Mindful of its potentially short-lived role he added, ‘Shale gas is incompatible with rapid emission reductions necessary to honour the 2ºC commitments. In an energy hungry world, with no meaningful carbon cap, shale gas use by Annex-1 nations will reduce the relative price of gas and coal elsewhere, and could therefore increase there use. With the gas being combusted in addition to coal and not as a substitute’.

Further information

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