Photo: finan.frank.blogspot.com
Researchers at the Tyndall Centre at Manchester University, England, investigated the impacts of shale gas on the environment and climate change. The exploitation of shale gas, or shale, is launched in the U.S. and will begin soon in Britain. Here the 11th and final part of a loose translation of the preliminary report from the Tyndall Centre for Climate Change Research. The original is here:
http://www.tyndall.ac.uk/shalegasreport with a link to download the report in pdf format of 87 pages. 
The report's title is: 
5. Conclusions 5.1 Switching context
5.1.1 Operation of the gas shale shale containing natural gas geological formations of organic rich shale, a sedimentary rock formed from deposits of sludge, sediment , clay and organic matter. Previously, it was not an exploitable resource, by cons, advances technology for drilling and well stimulation enabled the extraction of unconventional gas shale formations of less permeable. The extraction of this gas involves drilling vertical and horizontal in the vein of shale. Fluid and proppant agent (of support) such as sand are then pumped into the borehole under high pressure to cause fractures in the rock that contains hydrocarbons, a process called hydraulic fracturing. These fractures are beginning injected into the well and extend to several hundred meters into the reservoir rock. The gas can then escape into the borehole to the surface. The wells are usually grouped on a site that has about 6 individual wells. These sites are distributed on the surface of a density of 1 to 3.5 per square kilometer. To date, shale gas has been exploited only in the U.S. where production of shale gas has grown: it provided 1.4% of gas in the United States in 1990 but exceeded 6% in 2008. Energy forecasts expect the shale gas to meet a greater proportion of gas demand in the U.S. for the next 20 years by increasing the production of 93bcm in 2009 to 340bcm in 2035 an increase of 266%.
5.1.2 The case of Great Britain
Now there is no active exploitation of shale gas in the UK, or drilling sites (well pads), or horizontal drilling in the shale. There is, cons, preliminary exploration work currently in deposits in anticipation of future development. There is a high level of uncertainty about the potential of shale gas reserves in the UK, but if we rely on what is happening in America, the BGS provides that the potential gas reserves shale in UK could be 150bcm. The only well
shale assets in UK belongs to Cuadrilla Resources has received a permit for a project site exploratory Prees Hall Farm, Weeton, in Preston Lancashire in November 2009. Drilling at Prees Hall was completed December 8, 2010 and the rig should be moved to another drilling site in Grange Hill, 15 km from Prees Hall, where drilling will begin in January 2011. A complete hydraulic fracturing Prees Hall and is scheduled to begin in January 2011.
Preparations for a third exploratory well in Anna's Road are underway and a draft permit has been granted 17 November 2010. At the same time, the BGS note that comparisons with the United States to present these forecasts could prove to be incorrect. So it is possible that the shale gas resource could be more abundant.
5.2 The GHG emissions
5.2.1 Differences with conventional gas
We have assumed in this report that the direct emissions associated with combustion gas from shale will be the same as from gas to other conventional sources. For GB, the distribution of shale gas is the same as conventional gas and therefore will be subject to the same leaks. This means that the main difference between the shale gas and conventional gas is probably coming from the emissions generated during the various extraction processes. There are so few reliable data have made verifiable assessment of these emissions extraction problem. However, it has been possible using the emissions data provided for the Marcellus Shale in the United States to provide that the likely emissions generated by different methods when extracting gas from shale for comparison with natural gas.
The report estimated that emissions proceeded from the many:
- horizontal drilling;
- hydraulic fracturing and flowback;
- fugitive emissions during fracturing (these emissions are unknown and have not were included);
- transport of water;
- transporting brines;
- treatment of wastewater.
By combining the emissions from these processes, it gives us an estimate by wells drilled from 348 to 438 tonnes of CO2. These data increase if the well is fractured again, which could produce up to 5 times, and the report adds that the DECC refracture might recur every 4 or 5 years on producing wells.
The quantity of these emissions is dependent on the production rate of the well that is specific for each well. Looking at the examples of forecasts basin gas production shale in the U.S., we can predict that on average the additional CO2 emissions generated by the methods mentioned above account for between 0.14 to 1.63 tons of energy CO2e/TJ gas extracted. Value depends on the total volume of gas extracted from wells and the number of times that the well will be fractured again. In terms of the GB, although the yield per well is not mentioned for the basins of the GB, it is believed that CO2 emissions could be additional wells in the highest margin forecasts compared with the U.S., since the reserves of GB are potentially more low as U.S. tanks
Since during the combustion of 1TJ of gas could produce about 57 tonnes of CO2 emissions produced by the additional methods of extracting shale gas identified represent only 0.2 % to 2.9% of combustion emissions. As conventional gas, there will be more emissions from processing, refining and distribution. These additional emissions suggest relatively low profits to reduce carbon emissions if the gas shale was to replace coal. Burning coal produces about 93 tons of CO2/TJ. It is clear that even adding the additional emissions that come with shale gas, gas emissions would still be lower. The benefits increase when one considers that gas plants are more efficient than coal plants.
5.2.2 The impact on total emissions.
To examine the possible impacts of shale gas on CO2 emissions scenarios have been devised for Great Britain and the world.
For GB, 4 scenarios were developed: 2 assumed that the quantity of shale gas produced would be similar to that presented by the DECC (2010), are 150 bcm and 2 who assumed that the amount would double the first 2. For 2 scenarios of 150 and 300 bcm, two different levels of intensity extraction were used: one based on a Hubbert curve (bell shaped) which is often used to make approximations of extraction a resource that shows a rapid increase in production followed by a rapid decline in production. The other is based on the kind of growth as predicted by the U.S. EIA (2010b). All four scenarios are most shale gas operation until the year 2050 and the cumulative emissions from the consumption of this gas shale ranging from 284 to 609 MTCO2.
To provide context to these data, this amounts to total emissions for G.-B. from 2.0% to 4.3% of total emissions in the country according to the budget proposed by the Committee on Climate Change from GB Assuming that the carbon budget is met, this should add additional programs for G.-B. For example, it is possible that the shale gas from GB replace imported gas, although this would not cancel the need to import. However, it is also possible that the extraction of fossil fuels would further pressure on the efforts made to adhere to the carbon budget by reducing gas prices and accounting for investments which could pay for renewable energy. It is also important to remember that in a global system led by the energy market where global demand for energy is growing steadily, even if the shale gas was imported to replace the gax in Great Britain, No ' and not increasing its emissions, it is likely that this gas is simply consumed elsewhere, resulting in an overall increase in emissions.
The starting point for the global scenario is an estimate of global reserves of shale gas taken from a report by the U.S. National Petroleum Council (NPC, 2007). Three scenarios were then developed assuming different proportions of the total resource was effectively exploited (10%, 20% and 40%). Assuming that 50% of this resource is exploited by the year 2050, these scenarios generate cumulative additional emissions generated by the gas shale GtCO2 40 to 183, which gives an additional atmospheric CO2 concentration from March to November ppmv for the period between 2010 and 2050. However, in a world thirsty for energy, it is possible that the operation would be faster than that. What we can say with more certainty is that without serious limitations in carbon emissions, any emissions from shale gas will likely be additional, aggravating the problem of climate change.
- The emissions generated by the additional processes required to extract the shale gas is low (0.2% to 2.9% of emissions due to combustion).
- Regarding the extraction and combustion, the carbon emissions of the gas shale are much more abundant than conventional gas and are less than coal. It should be noted, cons, it was not possible to estimate fugitive emissions that could be generated by the extraction of shale.
5.3 The environmental impacts of shale gas exploitation
5.3.1 Pollution of groundwater
The potential for contamination of groundwater is a significant risk associated with extraction of shale gas. Although there is little evidence, it seems that the fluid used in hydraulic fracturing contains many chemical additives which are toxic to humans or wildlife. That the fracturing process can have impacts on water quality and threaten human health and the environment has prompted the U.S. EPA to instigate a research study complete question. Pending the results of this study, the state of New York has declared a moratorium on new wells. Pollution of groundwater may occur where there would be a catastrophic failure or loss of integrity of the borehole, or if contaminants can not migrate to the fracture in the shale to target underground passages. The risk of such pollution were considered minimal in a study by ICF International. By cons, this assessment was based on a risk analysis on fully constructed wells. History shows us that this is rare in projects complicated that mistakes are never made and the risk of pollution of groundwater wells evil facts must also be considered.
Consider any risk as insignificant is particularly difficult to justify given the documented examples that have occurred in the U.S., due to shoddy construction and / or operator errors it seems. These examples have shown high levels of pollutants such as benzene, iron and manganese in groundwater, and a number of explosions caused by gas accumulation in groundwater.
- There is clearly a risk of groundwater contamination caused by mining shale gas.
- It is important to recognize that most problems are due to errors in construction or operation and that they can not be eliminated.
- The search for the U.S. EPA should provide us with important new data to understand this.
- Not a serious limitation of carbon emissions, consumption of gas shale will increase carbon emissions, potentially in significant quantities.
- The exploitation of shale gas is expected to increase in atmospheric CO @ ppmv from March to November.
- The exploitation of shale gas could increase the difficulty of achieving targets for reducing carbon, for example by taking the place of renewable energy.
- Assuming that the carbon emission limits are strictly enforced, then the gas shale would make no difference, since the emission sources are inconsistent.
5.3.2 The pollution on the surface
Although it is not always possible to determine the exact cause of contamination of surface waters, identify the source of pollution of soil and surface water is easier. There are several potential sources of pollution including: rock drill cuttings and drilling muds, additives for chemical fracturing fluid and the fluid flowback of the fluid containing the toxic chemical that comes to the surface after fracturing. These could take many paths as potential sources for pollution incidents including equipment failures and human errors of the operator. Unsurprisingly, a number of incidents have been reported in the U.S.
While these dangers are similar to those known in several industrial processes for extracting gas from shale, which may occur in a very short period time during the site construction and initial drilling. That means investing in a system of physical containment, as it could be expected in many cases with such dangers, would probably be less feasible.
5.3.3 Water consumption
extraction of gas from shale requires large quantities of water. To carry all hydraulic fracturing operations on a drilling site six wells, between 54 and 174 million liters of water, equivalent to 22 to 69 Olympic swimming pools. If Great Britain is planning to produce 9bcm shale gas annually for 20 years, it would require between 1, 300 and 5,600 million liters of water per year. This compares with current levels of levies by the industry (except for generating electricity) 905.000 million liters of water. The exploitation of shale gas at this level would therefore increase the levies of 0.6%. While this may seem a low additional levies, it must be remembered that:
- This implies an annual demand of water throughout the country. It is clear that the actual demand of water will concentrate in areas where shale gas will be exploited and could add an additional heavy burden in these regions;
- Water resources in UK is already under stress, making the additional levies difficult;
- Impacts on climate change could add even more pressure on water resources in the country.
Since water is mostly used for a short period of time during the initial fracture, the most obvious way to get water on the site in UK would probably be taken directly by truck.
- Large quantities of water are needed to extract the shale gas, and this could put significant pressure on water sources in areas where there is drilling.
- Impacts on climate change could further worsen the problems associated with them.
- very high standards of risk management will be maintained at all times if we are to prevent pollution of surface.
5.3.4 Other issues
Considering the possible exploitation of shale gas in Britain, it is important to recognize the differences with what is happening in the U.S., which leads us to look on other issues that should concern us.
The noise pollution
Given the high population density and inevitably most of the sites operating shale gas will be located relatively close to population centers, noise pollution could be a significant problem. Activities such as Drilling imply that each site will drill noise night and day for a period which can vary from 500 days to 1,500 days.
Road traffic
Like noise, increased traffic, often heavy, comes with the exploitation of gas shale. It is anticipated that the construction of each wellhead require between 4.300 and 6,500 truck trips. This would significantly impact on local roads and intensity of traffic where the wellhead. The damage to roads which are not designed for such intensity of traffic caused by the drilling were issues in the United States.
impacts on the landscape
The construction of drilling sites is an industrial activity and demand for access roads, storage tanks, storage tanks, drilling equipment, trucks, etc.. The well sites occupy 1.5 to 2 acres each and will be distanced approximately 1.25 km square, each 3 km in length. 9bcm to produce gas annually in UK over 20 years, it would take 430 to 500 drilling sites and cover a land area of 140 to 400 square km. To give an idea, is about 400 km square area of the Isle of Wight. This intensity activities probably raise a lot of local opposition and could be seen as unacceptable by the general population. 5.4 To conclude
It is important to emphasize that one of the main information in this book is that there is very little background information for analysis to assess how shale gas could impact the emissions of GHG and impacts of the operation could have on the environment and health. Although every effort has been made to ensure the accuracy of the information in this report, it can only be as accurate as the information on which it is based. In itself, the lack Information may be in itself a valuable knowledge to know as much as other data on the evidence of contamination of soils and surface waters from the United States, and the need to apply the precautionary principle to the U.S. U. .- It is clear that the exploitation of shale gas in UK must surely be delayed until the security is not certain and that the security is not assured.
- For Great Britain, human population density and the high probability that the wells are close to population centers could produce problems of noise pollution, traffic and detrimental impacts on the landscape for residents.
The study of the U.S. EPA on the risks to groundwater will complete our knowledge on the subject, hopefully. With all this uncertainty around the environmental impacts associated with the exploitation of shale gas, it would seem sensible to wait for the results of the investigation by the U.S. EPA that will give us more information. The argument that the shale gas should be exploited as a source of energy transition to a low carbon economy seems weak. If we go by what happens in the U.S., there is very little evidence that the shale gas replaces coal now, or shale gas will replace coal in the future. It is possible that a small share of coal will be replaced by shale gas in some countries, but in today's world where energy demand is so strong globally, and without serious binding measures to reduce GHG emissions, there is very little incentive for prices to make substitutions for energy sources that are lower in carbon. It is very difficult to see anything other than seeing the shale gas consumed in addition to other fossil fuel reserves, adding to the burden of carbon. This could generate an additional 11ppmv CO2 above expected levels without shale gas, a figure that will rise while the 50% additional shale gas is tapped. We must point out that shale gas is not like oil or tar sands. The extraction process itself does not generate significant emissions compared with conventional gas extraction, but given the urgency and necessity that we reduce our carbon emissions, any additional fossil fuel source is only add up to the problem. The idea that we need fossil fuel transition is itself questionable. For example, in the scenario of the International Energy Agency, which determines a 50% reduction in carbon emissions by 2050, the transitional source of energy with more efficient energy production accounts for only 5% of the required reductions (IEA, 2010). If globally, we must achieve significant reductions in carbon emissions that are covered, so it's energy efficiency, carbon capture and storage, renewables and so on. who manage to make a difference. Although
could argue that the domestic exploitation of shale gas on an energy security would be valid, by replacing a portion of the gas imported by domestic gas, this is not the purpose of this report. In the UK, shale gas could replace coal and thus reduce emissions from GB, but with a carbon budget instead of coal (without CCS), it will be neglected in any way: Shale gas is not necessary for that to happen. And even if it did, given the massive emission cuts required and the need for carbon-free source of electricity in the next 2 decades, shale gas may be a major distraction for the transition to a network zero carbon. Given the need to invest heavily in infrastructure to exploit these resources, there is a danger that G.-B. committed in years of shale gas consumption, while the technology unproven carbon capture and storage are still to be demonstrated would be the only option for low-carbon electricity (and even that would not allow a rate captured 60% to 80%).
Consequently, this investment would be better placed in truly zero carbon technologies that would improve our options more effective long-term decarbonization of electricity.
At the global level, given the growth in energy demand equal or exceed the total GDP, and while there are no carbon constraints, the exploitation of gas shale will likely lead to an increased energy consumption and increased emissions. The Committee on Climate Change suggested that electricity should be decarbonised by the year 2035 (CCC, 2010), which result in climate change probably even more dangerous. For countries that have set a limit of carbon, such as GB, there could be incentives to replace the carbon with shale gas, it would probably result in a decrease in fossil fuel prices worldwide and therefore rising demand. Consequently, there is no guarantee that the consumption of gas shale in a country where there is a limit for carbon would result in an absolute reduction of emissions and could even lead to a global increase.
In addition to concerns for groundwater and emissions of greenhouse gases, it is important to remember that in terms of possible exploitation of shale gas in Britain, the high population density amplify several known problems in the United States. If serious amounts were to be extracted in Great Britain (9bcm the sample was used in the report but the scenarios include a higher annual production for certain periods), then this could have a considerable impact on already limited water resources and land.
Photo: journeyoftheforsaken.com
0 comments:
Post a Comment