Monday, October 17, 2011
Fracking, Burning Shale Gas and the Environment
Our modern society requires power and that is not going to change. The cost of power is a key factor in determining the cost of production, and the cost of living. In the 1990’s natural gas, sold for $2 per million BTUs after peaking in 2005 natural gas is now about $3.50-$4 per million BTUs, with this price and the advances in drilling the extraction of shale gas is viable and profitable. The techniques for fracking first developed in the Barnett shale in the Fort Worth Basin in Texas have been applied to a series of major shale gas deposits that could not have been viable without these advances in drilling and fracking. The Fayetteville shale, the Haynesville shale, the Marcellus shale reserves all in the United States and the Horn River shales in Canada are now accessible at current market costs. At the current rate of natural gas consumption North America is reported to have a 100-year supply of proven, producible reserves and even with expanded use of natural gas, there is more than a generation of currently accessible reserves.at that price we appear to have vast amounts of available natural gas.
Shale sourced natural gas could provide a reliable source of natural gas for our nation in this century. However we need to remember that the gas still is a limited resource and be cautious about what other impacts fracking might have on our other resources. Natural gas is the cleanest of the fossil fuels. Burning natural gas in the place of coal emits fewer harmful pollutants. Methane, the principle component of natural gas, is itself a potent greenhouse gas. Methane has an ability to trap heat almost 21 times more effectively than carbon dioxide. Concern for the potential impact of the release of greenhouse gases and other impacts from shale gas extraction have been raised by various groups. This year researchers at Carnegie Mellon University compared greenhouse gas emissions from the Marcellus Shale region with emissions from coal used for electricity generation. This study estimates the life cycle greenhouse gas (GHG) emissions from the production of Marcellus shale natural gas . The authors found that natural gas from the Marcellus shale had lower life cycle GHG emissions than coal for production of electricity by 20–50% depending upon plant efficiencies and natural gas emissions variability. The significant range in estimates is due to the variations in the ultimate production from a well (more lifetime production reduces GHG emissions) and differences in flaring, construction and transportation how carefully these steps are carried out.
At least in the medium term the environmental impact from power generation will be determined by the efficiency and care of how fuel is obtained, transported, generated and used. Improving efficiency is the low lying fruit that can have an immense impact and should not be ignored while we are busy dreaming of the someday world of renewable energy. Natural gas from shale rock is plentiful in North America. Despite billions of dollars in DOE solar generation loan guarantees the generating capacity of solar power in the nation will continue to be under 5% of power generation. Recent ambitious plans to convert the nation to renewable energy: build nuclear plants and solar and wind farms, were made under the assumption that natural gas prices would average $9 per million BTUs. At that level, electricity prices would have increased to costs of production and living significantly, but wind and nuclear power generation would have been competitive. Now, with natural gas at under $4 per million BTUs and more gas reserves announced each year, many of these projects suddenly look much too expensive and would never happen without mandated renewable portfolio standards and government incentives. The projects that get done will increase the cost of power when those costs are incorporated into the electric rate base.
Power plants can use several methods to convert gas to electricity. One method is to burn the gas in a boiler to produce steam, which is then used by a steam turbine to generate electricity. A more common approach is to burn the gas in a combustion turbine to generate electricity. Another technology that is growing in popularity is to burn the natural gas in a combustion turbine and use the hot combustion turbine exhaust to make steam to drive a steam turbine. This technology is called "combined cycle" or “natural gas combined turbine plants” and achieves a higher efficiency by using the same fuel source twice.
The CO2 emissions from all natural gas plants are less than to those produced by burning coal given the same power output because of the higher heat content of natural gas, and the higher overall efficiency of the gas generation plant relative to a coal-fired plant. Natural gas also allows for smaller ‘distributed generation’ plants, providing flexibility and local autonomy for generation. However, the gas well lifetime, care in obtaining and transporting the gas and the efficiency of the generation plant will determine overall environmental impact of gas power generation on our earth. Although power plants are regulated by federal and state laws to protect human health and the environment, there is a wide variation of environmental impacts associated with power generation technologies and as the Carnegie Mellon researchers found that natural gas from the Marcellus shale and probably all shale gas has lower life cycle GHG emissions than coal for production of electricity significantly better than the current standard.
Though there has been tremendous concern for the potential direct adverse impact that fracking may have on drinking water, geologists and engineers believe that there is little risk that the fracking “water,” a mix chemicals and water, will somehow infiltrate groundwater reserves though a fissure created by the fracking. It is believed though not documented and tested that the intervening layers of rock would prevent a fissure from extending thousands of feet to the water table. Data should be collected to test this belief as part of a careful monitoring and study of fracking and shale gas extraction. There are other risks in how we build wells and fracture the shale. Documented contamination to drinking water wells due to seepage of fracking water into drinking water wells through improperly sealed or abandoned drilling wells must be addressed.
The current regulatory framework concerning hydraulic fracturing, which is the core element in shale gas and tight oil extraction, has a number of gaps that need to be addressed before unlimited fracking takes place. There were several recommendations made in the report of the Shale Gas Subcommittee of the Secretary of Energy Advisory Board. The report had a rational approach to regulation recommending disclosure, testing, evaluation and modification of regulation and practices based on the information and data obtained. It assumes information and data will be gathered and analyzed. That is not being done. The data needs to be collected on a state and provided to the US Geological Survey and US EPA to consolidate on a national level.
Though the energy companies are beginning to gather baseline data for drinking water wells in the areas being fracked, the data collection is neither ongoing nor broad enough. Drilling requires large amounts of water to create a circulating mud that cools the bit and carries the rock cuttings out of the borehole. After drilling, the shale formation is then stimulated by hydraulic fracking, using up to 3 million gallons of water. Data needs to be gathered on the impact to water resources of supplying water for the construction of thousands of wells per year. For gas to flow out of the shale, nearly all of the water injected into the well during fracking must be recovered and disposed of. At under 0.5% by volume, the proprietary chemicals used in fracking total 15,000 gallons in the waste from the typical 3 million gallon hydro fracking job. The chemicals serve to increases the viscosity of the water to a gel-like consistency so that it can carry the propping agent (typically sand) into the fractures to hold them open so that the gas can flow. Determining the proper methods for the safe disposal of the large quantities of this fracking fluid that may also contain contaminants from the geological formation including brines, heavy metals, radionuclides and organic contaminants and monitoring the impact from this disposal must also be done. The deep well injection of the waste in Texas was associated with earthquakes and is believed by scientists to have triggered the earthquakes. The impact of so much waste water on our water resources must be measured and monitored. Finally, care must be taken to avoid degradation of watersheds and streams from the industry itself as large quantities of heavy equipment and supplies are moved on rural roads and placed on concrete pads. The watersheds must be monitored.
Other impacts from shale gas fracking and extraction is watershed impact and surface land damage due to construction of drilling pads, the transport and use of trucks, equipment, gas processing equipment and the creation of access roads in often remote areas. Other possible impacts are air emissions of pollutants and methane, groundwater contamination due to uncontrolled gas or fluid flows due to blowouts or spills, leaking fracturing fluid, and uncontrolled waste water discharge. Fracturing fluids contain hazardous substances, and flow-back in addition contains heavy metals and radioactive materials from the deposit. Experience shows that many accidents happen, which can be harmful to the environment and to human health. Many of these accidents are due to improper sealing of casings or leaking equipment. Furthermore, groundwater contamination by methane, in extreme cases leading to significant methane levels or even explosions from residential drinking water wells and potassium chloride leading to salinization of drinking water aquifer has been reported in the vicinity of some gas wells. The impacts can add up and make as shale formations are developed with a high well density of up to six well pads per square mile. Hydraulic fracturing means jobs and wealth, but the industry needs to develop adequate procedures, techniques and standards to minimize environmental impact and maximize gas recovery. Slow is fast.