Comparison of the Life Cycle Greenhouse Gas Emissions of Shale Gas, Conventional Fuels and Renewable Alternatives from a Dutch Perspective (2011)
Deze MSc scriptie is geschreven door oud-stagiair Atse Louwen.
This report, commissioned by Energie Beheer Nederland B.V., analyzes the life cycle greenhouse gas emissions of shale gas production and use as a fuel for electricity production, and compares shale gas with conventional natural gas, coal, wind energy, and nuclear energy in terms of life cycle greenhouse gas emissions. The aim of this study is to first of all rank shale gas in the current spectrum of electricity production routes, and assess the major factors determining the GHG footprint of shale gas. With this information both Energie Beheer Nederland and national policy makers gain insight on the effect of the use of shale gas in the near future.
Shale gas production has seen an enormous increase in the United States in the last years, has allowed the U.S. to become more energy independent, and has drastically increased the amount of natural gas reserves. This increase in production is primarily possible due to two advances in gas well drilling and completion: horizontal drilling and hydraulic fracturing. Especially the latter has been the subject of some environmental concerns. During hydraulic fracturing, large amounts of water, mixed with sand and chemicals in a total concentration of up to 2% are injected into the well at high pressure. The high pressure forms fractures in the shale rock through which the natural gas can escape. It is argued that due to hydraulic fracturing, a number of concerns arise. One of those concerns is that shale gas production has a dramatically increased greenhouse gas footprint due to the increased effort required to extract it and increased methane leakage from wells.
This study shows that overall, shale gas does have an increased GHG footprint compared to conventional natural gas, both when looking at production only and at the use as an electricity fuel. Overall, when used to produce electricity, the GHG emissions of shale gas are about 4.4% higher at 485 gCO2-eq/kWh compared to conventional natural gas at 465 gCO2-eq/kWh. Compared to coal fired electricity however, emissions of electricity produced with shale gas are much lower at only about 50% of coal emissions. A comparison with LNG imported from Algeria shows that compared to LNG, shale gas emissions are much lower, about 3% lower when comparing a fuel mix of 90% conventional natural gas and 10% of shale gas or LNG.
A concern with shale gas production lies with the uncertainty of the amount of methane released after hydraulic fracturing, when the water used for this purpose flows back out of the well. In the few available studies on this specific topic, a large range of methane emissions in this phase of the lifecycle is reported. If a worst case scenario is assumed, overall GHG emissions of shale gas powered electricity are about 15% higher compared to conventional gas fired electricity. Future research should establish clear figures for methane emissions after hydraulic fracturing to reduce this uncertainty.
Another factor that has a large influence in the overall result for the shale gas lifecycle is the total lifetime production per shale gas well. Data for shale gas wells in the United States show a large variation, partly due to the fact that shale gas in the United States is produced from a variety of locations. For the Netherlands, such production estimates are not yet available. To present more specific emissions figures for the Netherlands, this research should be updated with Dutch production estimates.
This study also confirms that both nuclear and wind powered electricity have much lower GHG emission per unit of electricity compared to the fossil fuel fired electricity plants. However, partly due to the specific origin of Dutch uranium, nuclear emissions are slightly higher compared to other European studies. Furthermore there is a large variation in literature data on emissions in various phases in the nuclear lifecycle. Offshore wind electricity has the lowest emissions of this study, at 11.2 gCO2-eq/kWh.