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'The Ugly Truth'

by Tracey Brown, director of Sense About Science

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Got a question about fracking? Get it answered by an expert

Some advocates of fracking in the UK claim that it could slash energy prices, reduce our carbon emissions and that environmental impacts can be kept to a bare minimum.

Others argue that it can’t be done safely – or that we’d be better off keeping it in the ground, moving away from fossil fuels and focusing on renewable energy.

Given the usually heated, partisan debate (and the myriad headlines it generates) you’d be forgiven for not knowing what to believe. Whether it’s claims about water contamination, fugitive emissions or earthquakes there’s certainly a need for this discussion to be better informed by what the science actually says. 

To try and help you decipher fact from fiction we’ve put together a panel of scientists to answer your questions. Could fracking be done safely in the UK? Would we need to earthquake-proof our towns and cities? Will it actually reduce our carbon emissions? Would we be better off keeping it in the ground? 

On Tuesday 12th May 2015 our expert panel, (Professor Geoff Maitland, Professor Zoe Shipton, Professor Michael Bradshaw, Professor Quentin Fisher, and Professor Kevin Taylor) answered your questions.

If you have a question on an energy related issue then get in contact with our energy panel via Twitter, @senseaboutsci using #energypanel, or email us at [email protected].


38. "People talk about fracking being used in the short and medium term. But building all this infrastructure for something that's only a 'transition fuel' is pretty short sited? How can we ensure we wean ourselves off fracked gas and onto renewables in the future?"

MB: "We are not actually going to have to build that much infrastructure as we already have a well-developed national and local gas transmission system and the potential production areas are near to centres of gas demand. There will need to be some investment in local processing facilities and pipeline connections, but those costs will have to be covered by the developers. The other factor to consider is that the shale gas production profile is one of a rapid peak and decline, with a long tail of relatively low production. We are only starting to understand the consequences of this in the US, but it means that the majority of an individual well’s production happens in the first few years. This means that to keep production up it is necessary to keep drilling, but it also means that it is relatively easy to ‘switch off’ if prices fall, and then ‘switch on’ if they rise. This is what we are seeing with tight oil in the US at the movement. This could mean that we see are relatively short-lived shale gas window in the UK during the 2020s into the early 2030, that then falls away as gas demand falls in response to the UK’s decarbonisation strategy."


37. "How much will #fracking cost in comparison to renewable #energy solutions to meet the UK's energy needs in the long term?"

MB: "This is impossible to know at the moment for the simple reason that we don’t know the cost of commercial shale gas drilling in the UK. Until the industry has been able to drill and flow-test a well to get a sense of how much gas can be produced, they won’t be able to work out the commercial viability of shale gas in the UK. The costs will certainly be higher than in the US, but the UK gas price is also significantly higher than the US price. As to a comparison with renewables, the cost of solar has fallen significantly, as has onshore wind, but offshore wind is very expensive. Furthermore, the renewables sector benefits from subsidies, though these are also falling. The shale gas industry will benefit from some tax concessions, and those using gas to generate power could benefit from capacity payments, but less than the 30 per cent of the gas used in the UK goes into power generation. The bottom line is that a shale gas industry will only develop in the UK if it makes commercial sense and we are some way from knowing if it does."


36. "Shouldn't we adopt a precautionary approach regarding fracking and instead look at the alternatives?"

MB: "I would certainly agree that the previous government’s statement about ‘going all out for shale’ was ill judged. The Conservative Party’s manifesto makes it clear that the new Conservative Government will continue to promote shale gas development. The approach being adopted is risk based in the sense that the regulators (DECC and DEFRA) believe that the risks are well known and can be managed with existing regulations and the application of the best available technologies and practice. The problem is that without actually drilling in the UK we don’t have the evidence base to support such an approach. But, this leaves us in a catch-22 whereby we don’t know what the risks are, but there are those that say we can drill until we have the evidence to know what the risks are. I agree that a more precautionary approach where we have a monitored programme of exploratory drilling and appraisal, couple with baseline monitoring and real-time monitoring of impacts would make sense. In effect, that is what will happen should Cuadrilla get its planning permissions to drill as the government has give NERC/British Geological Survey £31 million to allow monitoring of drilling activity. On reflection, had the government followed this more precautionary approach from the start the current level of opposition may have been lower, but the majority still remain undecided."


35. "With relation to your answer to question 23, Halliburton has been used to provide fracking fluids in Australia. BTEX chemicals have been used in fracking. Will Halliburton provide the fracking fluids in the UK?"

QF: "Chemicals will certainly be purchased from a very wide range of suppliers. I’m sure Halliburton will be a company that will submit tenders to supply a whole range of services to the fracking industry. Regulatory authorities, such as the environmental agency will assess the safety of chemicals used and the risks of them entering the environment. I find it rather odd that people get overly obsessed with what is being pumped so far underground that it has very little chance of polluting our environment yet are perfectly happy to allow the agriculture industry to spay a whole range of chemicals directly on to the food they eat."


34. "To what extent is there evidence of fracking causing pollution issues? Should this be a worry for nearby residents?"

QF: "I think the main pollution issue is simply CO2 emissions in the atmosphere than come with burning CO2 for energy. We clearly need to move away from fossil fuel usage and fracking for gas should only be used as a bridging technology until renewables become more efficient. In terms of pollution caused by the fracking process, I think the development of shale gas in the UK will be slower than in the USA and we have tighter regulations so I don’t think residents should be overly concerned about pollution."


33. "Fracking has been done in the past in this country, so why does so much controversy surround it now?" (James Clarke)

QF: "Although fracking has been widely used in the UK the volumes of fluids and proppants pumped into the ground are far less than have been used on the onshore UK but are similar to what have been used offshore UK and widely onshore USA. However, I think there are two big causes of the current controversy. First, the film Gaslands, which is a widely inaccurate narrative of the environmental impacts of fracking has been taken on board by the general public as being factual. Secondly, green groups are quite rightly lobbying to cut carbon emissions and have targeted the shale gas industry. Instead of being honest and arguing the case that we should reduce emission they have instead used scaremongering (e.g. water contamination, earthquake risk, water usage etc) to increase protest from the general public in an attempt to reduce gas production."


32. "Is the research in the US around earthquakes and increasing frequencies relevant to the geology of the UK?"

ZS: "Is the US experience relevant for the UK? Yes and no. Yes, because physics is physics and we can learn a lot about rock mechanics by studying the US earthquakes. No, because whether a given fault will slip during a frack job or not is dependent on 1) the stress in the vicinity of the fault (the orientation and magnitude of the geological forces on the fault), 2) the mechanical properties of the fault (a function of the rocks that the fault is cutting (see Q 19) and 3) how close the fault is to slipping. Ideally an operator would undertake a survey of the faults in the region of their wells, and measure the stresses down the hole. This would need to be done on a site by site basis as faults and stress are variable from site to site and this is now required in the Hydraulic Fracturing Plan part of the DECC guidance. Even without this requirement, operators measure down-hole stress anyway in order to design the most effective frack jobs – i.e. they need to know which direction the fracks are going to propagate (stress direction) and estimate the pressures they will need to use to frack (stress magnitude). Mapping faults is less straightforward, and I don't know if this is routinely done in the US, but the DECC guidance makes it a required part of getting permission to frack."

31. Re question 24, "If "damage compromised the well beyond repair, that section of the well could be plugged and abandoned" - But then too late!" (@Refracktion)

ZS: "Damage to one segment of well casing or cement does not mean that there will be a pathway for methane or fracking fluids all the way to the surface. It is possible to run logging tools to image behind a well casing to check the integrity of the cement in the well."

30. "Where the geology is so faulted, is fracking likely to give rise to depressurisation of any underground aquifers?" (Christine Stanton)

KT: "Underground aquifers are not pressurised in the sense gas reservoirs are. Aquifer pressure is much lower and is controlled by hydraulic head pressures rather than from pressure derived from depth. Also, fracturing operations take place at depths much greater than freshwater aquifers are present at."

29. "The chemicals that are pumped into the ground – what do they actually do? Are they meant to make getting the gas/oil out of the ground easier? How do they do that?" (Holly Childs)

KT: "The chemicals are included for a number of purposes. These include viscosity enhancers (which is often Guar Gum) which help carry sand into fractures and keep them open. There are also chemicals to help the gas release from the pores in mineral and organic surfaces. Plus there are chemicals to stop biofilm (microorganisms that stick to surfaces) growing in the borehole that would otherwise block flow."

28. "Isn't it true that most of the shale gas in the UK is actually inaccessible?" (James Perry)

KT: "There is not a straightforward answer to this. By the very nature of gas reservoirs it will not be possible to access all of the gas, and the US experience suggests that more of the gas is inaccessible than accessible. The ratio of these two will depend on the geology of an area, advances in technology, and the economics of gas prices."

27. "Afraid I'm going to sound naive here, what replaces the gas in those spaces where it is extracted from?" (Adie Fletcher @adiefletcher)

KT: "In a sandstone – ie conventional – reservoir, the oil or gas would be replaced by water from below. In shale gas though, due to the very low permeability, water replacement is unlikely. What most likely happens is that the holes which were filled with gas (which are very small) will remain empty and undergo some compaction and deformation."

26. "What are the limitations on land after a fracking site is abandoned?" (@hagitw)

QF: "There are no limitations on the land. The rocks from which the gas is taken is very stiff (strong) so unlike gas production from conventional gas reservoirs and/or coal mining there will be no subsidence issues. There is negligible infrastructure left after the wells have been drilled and fractured so even the land from where the wells are drilled could be used as normal when the equipment used for drilling and fracturing has been removed."

25. "What resources are recommended to help the public understand #shalegas? We've recently published our own: http://knowledge.energyinst.org/collections/shale-gas" (@EnergyInstitute)

GM: "I think we need a mix of things. Web-based information such as that posted by the Energy Institute and others is essential and getting more comprehensive and accessible. The industry could develop ‘roadshows’ that have demonstrations, models, and take experts to communities that have concerns and want to know more. Local panel discussion involving experts and those challenging the technology go a long way to getting the concerns out in the open and the evidence presented clearly in a local context. Getting programme makers interested in the topic would ensure reaching wide audiences.

Also there is too much parallel processing – some coordination between industry, the Department of Energy & Climate Change, the Office of Unconventional Gas and Oil, and NGOs would help to be more effective in making evidence-based material available, with FAQs having some attributable sources."

MB: "The problem is that most sites have a particular take for or against shale gas development in the UK. The Department of Energy and Climate Change has shale gas pages that provide lots of information. The British Geological Society has pages on its site that explain the geology in the UK and the nature of shale gas. The UK Onshore Operators Group’s site presents the industry’s view. They also sponsored the ‘Lets Talk About Shale’ site with lots of questions and answers. There is also Nick Grealy’s Not Hot Air site that is pro-development. There is an opposing ‘Talk Fracking’ site sponsored by various celebrities. ‘Drill or Drop’ purports to present an independent view, and The Shale Gas Task Force has its own site. The various NGOs also have pages on shale gas. There are also a huge number of sites in the US, but they are specific to operations there. In Europe there is the Shale Gas Information Platform (SHIP). I could go on, the point is that there are lots of sites; the problem is working out where they are coming from."

ZS: "I would direct people to the Royal Society and Royal Academy of Engineering Report, and the Scottish Government's Expert panel report. These were both written by panels of independent experts, and were peer reviewed. Both panels also contained environmental experts.

Two excellent resources around energy use are the DECC energy pathways calculator and the book Sustainable Energy - without the hot air. The pathways calculator allows you to be boss of the country, make all the decisions, and see what the cost, security and environmental implications are. The book straightforwardly lays out what the UK energy demands and supplies are and asks can we do it all with renewables and if not what are the barriers.

The debate around shale gas really needs to part of a larger debate around energy. If we say no to shale gas we have to think about what we are saying yes to instead. There is a phrase that often gets used - the energy trilemma, which can be summarised as:

  • How can we get the energy we need at a cost that wont put people into energy poverty,
  • in a secure way that reduces our reliance on imports from countries that may be politically unstable, and/or have less stringent health and safety/environemntal legislation than the UK,
  • in the least environmentally damaging way (including climate change)?"

24. "Does the panel agree that the risk from fracking-induced seismic activity routinely gets mischaracterised as being a low risk to roads and buildings, instead of an alarming risk to well integrity?" (John Hobson)

ZS: "I agree with the questioner that seismicity from fracking, or associated wastewater disposal (which would not be allowed in the UK or Europe), is a very low risk to roads and buildings. The risk of damage to a well is larger but still relatively low.

Remember that risk is likelihood of occurrence multiplied by the hazard. The likelihood of an earthquake related to fracking being felt at the surface is very very low: a handful of recorded events in millions of frack jobs to-date. The hazard is also low due to the rock mechanics: shale is a relatively flexible rock, so the magnitude is not likely to exceed 4. According to the British Geological survey this could be "Felt by many people, often up to tens of kilometres away; some dishes broken; pendulum clocks may stop." The likelihood of an effect on a well is therefore also very low, though the hazard is slightly greater. If an event damaged the well casing or cement it could affect the integrity at that point in the well. If that damage irreparably compromised the well, that section could be plugged and abandoned."

23. "Which chemicals are used in fracking fluid?" (Ira)

"What chemicals are pumped into the earth? (Colin Greenaway)

QF: "Generally, water makes up 98 to 99.5% of fracking fluids. A wide range of chemicals can be added to water, but these vary so widely that it is difficult to make generalizations. Common chemicals added include gelling agents (e.g. guar gum); biocides e.g. (ammonium chloride), breakers (e.g. magnesium oxide), friction reducers (e.g. methanol) and corrosion inhibitors (e.g. formic acid)."

22. "What is the average life time of a fracking site? How long does it take to pump all the shale gas?" (@hagitw)

QF: "Firstly, gas is not pumped from a fracked well – it flows due to the expansion of gas as pressure is reduced. Gas may continue to be produced from a well for decades. Overall, the rate of gas production falls very rapidly with time. So for example, the gas production rates after a year could be something like 10% of what they are when the well is first fracked. It is possible to refrack wells periodically to increase production rates."

21. "This is one of many issues to do with the environment that people immediately take sides about, before seeing any evidence. How can we create a new kind of forum for evidence-based discussion rather than merely leave it to our politicians to decide for us?" (Julian Simcox @JulianSimcox)

MB: "The problem is that we have a highly polarized debate with the Conservative Government and onshore oil and gas industry on the one hand saying this is too good an opportunity to miss; and environmental groups and many in local communities, one the other hand, saying that the health and environmental impacts are too great. Both sides pick and choose their information and there is hype on both sides. The Shale Gas Task Force chaired by Lord Chis Smith is trying to provide some independent evidence, but the task force is funded by industry and will not be seen as independent by the environmental groups. The Royal Society report in 2012 did suggest a large-scale academic enquiry, but this has not happened. However, there are academic groups seeking funding for research that would provide an independent evidence base. There is a public enquiry promised in Scotland and a moratorium in Wales and Northern Ireland, but while the Government in Westminster is going ‘all out for shale’ there is little prospect of a wider debate in England."

20. "Why are the estimates for how much gas fracking can provide so variable? Which estimates can we trust?" (David Norton)

KT: "We use estimates from the US experience, but as UK rocks are different in age and composition we cannot reduce uncertainty on gas reserves until more exploration is undertaken. The amount of gas that can be released from a rock will depend on a number of factors that vary from one part to the next, and over a range of scales. These include the amount of pore space (holes) in the rock to hold the gas and the effectiveness with which the rock can be fractured by hydraulic fracture stimulation."

19. "Would you agree that it is extremely risky to frack where the geology is heavily faulted?" (Christine Stanton)

ZS: "The main risk attached to [geological] faults in shale gas is commercial. Faults often displace layers of rock vertically. A lot of the terminology around faulting comes from the days of hand carving coal faces. If you were mining along a coal seam and hit a fault, the odds are you would loose the seam. It would have been displaced higher or lower on the other side of the fault, depending on what sort of fault it was (normal faults displace the block above the fault downwards and reverse faults displace the block above the fault upwards). The same will be true in a heavily faulted shale gas reservoir – if you were drilling horizontally along your layer and hit a fault, you may well loose the productive layer of rock. You can map where the likely faults are in advance of drilling using geophysical surveys such as seismic data, but these have limited resolution and generally can't resolve features with a vertical offset lower than 10-20m. Operators will need to map any faults to evaluate the commercial risk in advance of any drilling, but are still likely to find small-scale faults that such surveys can't resolve, which could be a problem. However there are now geophysical logging tools which sit just behind a drillbit, which allow operators to "geosteer" the bit to follow the most productive layers. The other risks that have been talked about in the context of faulting are seismicity (see question 3) and the risk that a fault will transmit fluids. The process of faulting affects the rock by cracking it and grinding it up as the two blocks either side of a fault move past one another. This can change the permeability of the fault rock compared to its host rock (permeability is a way of expressing how easy it is to conduct a fluid through a rock). From a review of the literature on faults cutting shales, the majority of them have reduced permeabilities compared to the host rock – this is because the process of grinding mixes the clay in the rock through the fault rock, and clay particles tend to clog up the permeability."

18. "#energypanel - have we had a proper conversation with the public on fracking in our energy supply options, and if not should we?" (Alan Mercer)

QF: "The fact that significant numbers of the general public have misconceptions about fracking suggests the gas industry hasn’t been particularly good at getting their points across. There clearly needs to be continued debate about how we generate energy in the UK as new technologies are taken on board and recently adopted technologies are tested. Energy always comes at a cost and the public should have a say in how these costs are weighed up against each other."

17. "How many litres of water do you use to extract one litre of gas or oil by fracking?" (Julia)

GM: "This is difficult to give a precise answer to since on average about 5 million gallons (about 20 million litres) of water are needed to fracture a typical deep shale gas reservoir per well, and this is a one off use. You then produce shale gas for many years, and it depends on the reservoir gas reserve and the duration of economic production as to eventually how much gas you produce for that water outlay. Typically 1000 Mcf, or 30,000 litres of gas are produced from a shale gas well per day. Let’s say we produce for 20 years…that is about 2 x 108 litres of gas. So that comes to about 100 millilitres of water per litre of produced gas. Clearly this is very approximate but gives a good order of magnitude for a productive site."

16. "What would the panel consider to be the minimum safe distance between a fracking site and residential properties?" (trina)

ZS: "About 1 vertical km! The recent British Geological Survey estimates of resources in the Central Belt of Scotland considered a minimum depth of resource to be 805m, based on a depth cutoff of 500m plus an additional 305m to account for the likely vertical extent of hydraulic fracture heights (Monaghan, 2014). There are reasons of rock mechanics why you would want to stay deeper than 500m, as well as safety. The main problem with putting a frack site very close to a residential property would be noise, dust and traffic, but this is similar to any construction project. The average length of time that a frack site would be under construction for is substantially less than that of a large building going up. I believe there is a fracked shale gas well in the grounds of Dallas Ft Worth Airport."

QF: "I don’t see any significant safety concern in having a fracking site directly adjacent to a residential property. The increase in traffic and noise while the site is being drilled would mean that one would preferably drill away from residential properties. However, the increase in traffic and noise would be similar to any medium sized building project (eg building a supermarket) and that happens extremely close to residential properties."

15. "Are you planning any fracking sites near London?" (Julia)

QF: "I don’t think that there are currently any rock formations known to be likely to contain gas or oil directly below London. However, if they were found I wouldn’t see any safety reasons why not to hydraulically fracture close to London."

ZS: "'We' are not planning any fracking sites as we're a bunch of academics not a hydrocarbon company! The Government held the 14th round of onshore oil and gas licensing last year and the result should come out soon, which will show who has bid for which licence blocks. The whole country is divided into blocks and this webpage shows the blocks that were up for consideration in the 14th round. Some of those were in London area, but just because a block was up for consideration, does not necessarily mean anyone will have bid for them, or that if they were awarded a licence, that they would end up getting planning permission etc."

14. "How will fracking affect the UK's energy security?" (@BilboGeogAmb)

MB: "The UK Government sees energy security as related to two issues: the physical security of supply – can we guarantee access to the gas supplies that we need, and price security – can we access that gas at prices that are affordable to our economy and population. When it comes to physical security, the level of import dependence and the diversity of supply are paramount. At present we import about a half of the gas that we consume. Those imports come by pipeline from Norway and from the continental gas market and also as LNG to three terminals.

As our production declines in the North Sea and in the absence of significant shale gas production onshore, we could be importing 70% of our gas needs. But the diversity of supply source should ensure physical security of supply. How much we will have to pay for that gas is uncertain. Finally, if we reduced our gas demand through energy efficiency and alternative sources of energy, that would reduce the volume that we need to import, and that would improve the UK’s energy security."

13. "Labour manifesto aim: 'zero carbon electricity by 2030' - does that slam the door shut on #fracking?" (Dan Curtis)

QF: "I would have thought that for power generation one would need to link gas-fired power stations with CCS [carbon capture and storage]. However, shale gas can also be used to provide fuel for the chemical industry so either way it would not close the door on shale gas production."

12. "Could you provide a "greenness" index for gas retrieved through fracking vs other fuel (I realise this is hard)? I would be interested in how such an index would be weighed against the cost of retrieval, factoring in the survey. For instance, if coal costs X per joule of energy it provides, and each joule gives out harmful emissions Y, Z, ... If I were to classify energy sources like that, where would fracked gas be?" (@gpap)

GM: "To answer this question one needs to do a ‘cradle-to-grave’ energy and environmental impact analysis for every energy source. Several groups are carrying out such analyses in the UK (eg DECC's energy and carbon calculator tools, Professsor Adisa Azapagic, University of Manchester or Professor Nilay Shah, Imperial College London), but they are quite complex and require good quantitative impact data. Qualitatively, shale gas takes less energy to produce than coal or oil but more than conventional gas. In terms of greenhouse gas emissions in use, shale gas is the same as conventional gas in emitting 50% less CO2 than coal or oil. The environmental impact risks during production are low if the processes are engineered, managed and monitored using well-established standards. There are short-term disruptions to local communities during the drilling and fracking of the wells, but the local footprint of the wellheads is small and comparable or less than the installation and running of wind farms and large solar panel arrays. The cost of energy production from renewable sources is still higher than for gas. Adding carbon capture and storage (CCS) to centralised facilities using gas would reduce greenhouse gas emissions to very low levels and make gas almost as ‘green’ as renewables. In the absence of CCS, my (cost x CO2 footprint) per joule ranking would be wind ~nuclear < solar ~ biomass < conventional gas < shale gas < oil < coal. You can test these things out using the DECC carbon calculator tools at http://www.globalcalculator.org/, http://my2050.decc.gov.uk/"

11. "What are the benefits of fracking – does it have significant economic impact? And does this outweigh the risks to the environment and human health?" (Katy Stubbs @KatyLStubbs)

MB: "In the UK, the government and industry has argued (and it remains the case based on the Conservative Party manifesto) that the development of shale gas will attract significant investment to shale gas producing regions (at present most likely the north of England), create new jobs (and preserve existing ones), improve energy security by reducing import dependence (which also benefits the UK’s balance of payments) and also promote the decarbonisation of the energy mix. The scale of these benefits is uncertain and those that oppose shale gas development certainly think that they do not outweigh the risks to the environment and human health. The government maintains that those risks are well known and can be minimized by existing regulations."

10. "What are the risks in an abandoned HydroFrack site?" (@hagitw)

GM: "The risks of an abandoned (non-producing) shale gas well, created by hydrofracturing, are essentially the same as any abandoned oil and gas well. If the wellbore is not properly sealed (eg with an incomplete cement sheath binding the well casing to the rock) there is a risk that gas from the shale will build up in pressure and find its way to the surface – gas seepage. This just means that well abandonment best practice must be followed: impermeable plug seals should be placed in the well, and the well sealed with a high quality cement, resistant to degradation by any reservoir fluids that might come into the well from the shale. This is standard and well-engineered practice. The wellhead should be continually monitored for gas leaks and seepage.

Once the wellhead is closed and sealed, there is a slight risk that the gas in the shale might migrate through natural fractures connecting the shale to higher regions subsurface rock. So continued monitoring of near-surface aquifers should continue, as during production, though contamination from residues from the fracturing process will not occur as all the fracturing fluid will have been removed in the early stages of production. Similar monitoring procedures will be standard practice during well production as well."

9. "In the UK what prevents companies from fracking where they want? And what are the licenses in the US? Are there any economic 'perks' for people wanting to frack?" (Hannah Rodriguez)

MB: "First, to be able to drill you need to get a Petroleum Exploration and Drilling Licence (PEDL) and these are auctioned by the Department of Energy and Climate Change (DECC) in a so-called licencing round, the 14th round is underway with over 90 licences bid for. So, you can’t drill just anywhere you want. Once you have your PEDL you need to get various permits from the Environment Agency and the Health and Safety Executive. You also need to get planning permission to drill from the County Council and this considers a wide range of local planning issues.

As for economic perks there is agreement with government and industry on a £100,000 community payment per well site and a share of 1% of the value of production. There are also modest payments to landowners. You can find more on this at the website of the UK Onshore Operators Group and DECC’s Shale Gas site. In the US licenses are required, but there are various loopholes and regulation is a state and county issue, rather than a federal issue and there is a great deal of variation between states."

8. "How can we streamline the permissions/licencing process in the UK? With only 7 shale gas wells drilled in the UK progress is painfully slow. The lack of data makes resource estimation impossible at the moment." (Tony Grindrod)

GM: "The new revised policy paper issued by the government and regulators earlier in May (‘2010-2015 government policy: energy industry and infrastructure licensing and regulation’) will hopefully help to accelerate this process, alongside the newly created Oil and Gas Authority. The paper indicates that the industry expects 20-40 new sites to be developed within the next 2 years. The Office of Unconventional Gas and Oil has been set up to encourage this process and the industry has agreed a community engagement charter, whereby it will pay £100,000 per exploration well for local community benefits and 1% of subsequent revenues. It would be good to see some explicit shale gas production targets from the government to drive an accelerated licensing process in addition to these measures."

7. "Could you please explain the difference between fracking and Underground Coal Gasification (UGC)? Is one safer than the other and how do they compare environmentally?" (Dawn Ewing @DawnieDimps)

Professor Kevin Taylor: "Fracking, or hydraulic fracturing, is a physical process by which fractures are created in the shale rock in order to release the gas (or oil) that is trapped in the rock. UGC is a process by which coal is partly combusted underground to produce gases (a mixture of hydrogen, carbon monoxide, carbon dioxide) which can be used to generate electricity at the surface. Both can be undertaken safely but due to being quite different processes a comparison of their surface environmental footprint is not straightforward."

6. "I've seen videos online of people lighting water from their taps on fire and claiming it's due to nearby fracking wells. Can fracking make my tap water flammable?" (Ian Bushfield @ibushfield)

QF: "Fracking is very unlikely to make your tap water flammable. The video that you have seen is most likely one of the cases where a water well as been drilled through rock (e.g. coal) containing gas and the well has not been sealed properly; it was not caused by hydraulic fracturing."

5. "Surely a dash for gas will bust our carbon reduction budgets? Better off keeping it in the ground." (James Clarke)

Professor Quentin Fisher: "I don’t know anyone who projects that we will be carbon free anytime in the near future. I believe it’s far better to use gas instead of coal for energy production as the latter is far more dangerous to mine and CO2 emissions are higher. Replacing domestic gas use is not going to happen soon, meaning that we will need to continue producing gas. I would much sooner the gas be produced in the UK than abroad as our safety standards will be higher, it will help our balance of payments deficit [where the UK imports more goods and services than it exports] and create UK jobs."

4. "Is fracking investment in wrong direction? In South West @MollyMEP shows 113% energy can be met by renewables." (Lee de-Wit @leedewit)

MB: "We do need to move away from fossil fuels and get our energy from renewable and low-carbon sources, but that is going to take quite some time. For the next couple of decades at least in the UK, natural gas has a role to play as a bridge to a low carbon future. But whether or not that demand for gas is satisfied by shale gas is a different question."

3. "Fracking causes earthquakes, and getting rid of fracking waste water causes earthquakes. Isn't this a big concern for a heavily populated country like the UK?" (Judith Schmidt)

Professor Zoe Shipton: "We need to define here what is meant by earthquake. Propagating fractures cause tiny events that can be picked up by sensitive microseismic instruments. These are usually placed down a borehole to avoid the background noise that comes from traffic etc, and can be monitored to see how the fractures evolve with time and between jobs. From US data, these are usually magnitude 1 to 2 and will be undetectable by people at the earth's surface (earthquake magnitude is measured on a logarithmic scale, remember, so a magnitude 2 is 10 times stronger that a 1, a magnitude 3 is 10 times stronger than a 2, and so on). Very few frack jobs have caused events large enough to be felt by people at the surface.

The two events in Lancashire in 2011 were the first recorded example of what is called "felt seismicity" linked directly to a frack job (magnitude 1.7 and 2.3). They were probably caused by fluid from a fracture entering a fault that was already close to failing. The events were below those commonly felt in old coal mining areas of the UK (up to magnitude 4). Whether an earthquake is felt by the public or not depends where you are – a magnitude 2 to 2.5 is unlikely to be felt in an urban area where background vibrations from traffic are of similar magnitude.

Wastewater from conventional hydrocarbons and shale gas in the US has been disposed of by pumping underground. This would not be permitted by regulators in the UK. Wastewater disposal impacts a larger volume of rock and for a longer period of time than in a fracked shale gas well. In the US this has caused events up to magnitude 5. An event of this size is unlikely to cause any damage to buildings. See here http://earthquake.usgs.gov/learn/topics/mag_vs_int.php

Seismic events could potentially damage the integrity of a well if the event caused shearing of the well casing – indeed, this did occur in Lancashire. This is not uncommon in the industry and an operator could run down-hole tools to assess the extent of any damage. In the event that any damage compromised the well beyond repair, that section of the well could be plugged and abandoned."

2. "Regarding the ASA ruling on the Greenpeace advert. Is there a scientific consensus that fracking will not lower prices?" (Jane Turner)

"Do you agree with @ASA_UK that claim "experts agree [UK shale gas] won't cut our energy bills" is misleading?" (Christine Stanton)

Professor Michael Bradshaw: "This is a complicated one. The complaint was made because the Greenpeace advert suggested that there was consensus that shale gas development (in the UK) would not bring down gas prices. As the complainant, Labour Peer Lord Lipsey, maintained, there is a range of views on the subject. The UK has an open gas market with supplies from our own continental shelf (which are falling), the Norwegian continental shelf, supplies from elsewhere in Europe via the interconnectors and also supplies from the global LNG market. The UK gas price is determined by gas-to-gas competition and the laws of supply and demand and is known as the National Balancing Point (or NBP for short). As we don’t know what the future scale of domestic gas production might be, what future demand might be, or what future conditions might be in the wider European gas market or the global LNG market, we cannot say with any certainty what impact shale gas production might have on future gas prices in the UK."

1. "So how does fracking actually work? You pump water down a hole and the gas flows back up with the water?" (Kelly Green)

Professor Geoff Maitland: "Water containing sand or other fine solids, sometimes with additives to thicken the water and keep the sand in suspension, is pumped into a well at pressures that fracture layers of shale rock. The layers are selectively exposed to the pressurised fluid through perforations in the steel casing that lines the well. The fractures propagate into the shale formation and the fluid flows into them, continuing to pressurize the rock and creating a network of fractures until the pressure energy is dissipated, filling the fractures with the sand, or ‘proppant’ as it is called. The pressure in the well is then reduced so that it is now lower than in the reservoir; two things happen. The fractures would close up unless they are kept open by the sand proppant – so they remain open and provide a high flowrate pathway for the gas within the shale to flow out, rather than being trapped in the very low permeability unfractured shale rock. The pressure gradient (lower in the well than the reservoir) then causes the water (with some gas) to flow back out of the fractures into the well and back to the surface where it is collected (and treated and sometimes re-used). The low pressure in the well then sucks the shale gas into the fractures, which then flows along these out through the perforations into the well, and then flows up to the surface, often several kilometers up, to be collected at the wellhead."

 

 

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