A number of scientific studies illustrate the fact that replacing coal-based fuels with natural gas can cut back on greenhouse gas emissions. Most reduction estimates are somewhere between 37 and 54 percent, though these figures depend on the age of the plant being upgraded and its current efficiency. However, leakage threatens to be a serious problem. This is especially true of production facilities located at shale gas wells.
Transport Natural Gas Leakage Rates
The production, transportation and storage of natural gas provide ample opportunity for at least some volume of gas to vent to the atmosphere. Current estimates of pre-plant natural gas leakage rates are somewhere around 2 percent. A few studies indicated even higher leakage rates.
Methane makes up the bulk of natural gas, and this is a rather potent greenhouse gas in its own right. Higher methane leakage rates translate into a lower environmental advantage.
Fixing the Problem
Leaked natural gas is both an environmental and economic concern. Fortunately, there are a few things being done about it. The United States Environmental Protection Agency’s Natural Gas Star is a voluntary partnership that works on physically fixing leaks. They locate stress points and physically reinforce them. Work crews are also doing this on a smaller scale at several locations across the country.
New devices are being designed that help to prevent gas from venting out of pipelines. These devices should help to prevent at least some of the leaks that occur during the transportation phase.
Shale Gas Fields
Production of natural gas is up in the United States as the result of increased shale gas development. Shale fields are often victims of what some call fugitive emissions. These small released of natural gas aren’t major, but become a problem over time.
Engineers are now developing ways of not only preventing these leaks but also harvesting them. Energy expert Daniel Yergin wrote that over one third of all natural gas produced in the United States comes from shale fields, so this kind of technology will become increasingly important in the near future.
Financial experts are also excited about sequestering leaked natural gas reserves. Fugitive emissions represent lost product, and this translates into lower revenue for shareholders. Recaptured gas can be added to the existing natural gas supply, and that represents higher revenue returns. Many shale gas field managers view purchasing sequestration equipment as an investment for this reason. Small local firms manage some fields, and these businesses need to ensure that every last bit of gas they produce gets captured and sold at a profit.
Unloading Phase Challenges
A good amount of natural gas is liquefied before being moved. Whenever these liquids are placed into transit containers, some of the fluid sublimates back into methane gas. This gas is lighter than air and will begin to move upwards into the upper atmosphere as soon as it escapes the facilities where the liquid is being poured.
Engineers think that they might have found some answers to this environmental problem. Pneumatic devices are used to load and unload liquefied natural gas. Improvements to the loading devices are helping to cut down on how much fluid undergoes sublimation. While this sort of research is still in its infancy, engineers hope that it will soon start paying big dividends.