How Long Will Natural Gas Last Without ElectricityThe natural gas feeding your house gets its compression from higher pressure "transmission" gas lines. Natural gas has pressure coming straight out of the wellhead, but it needs help to get to its ending destination, your house. The gas is piped from these lines through "regulator stations", belonging to your natural gas provider, which step down the pressure to the lines going to your home. At your meter is another regulator which also may step down pressure to your home. The vulnerability and fragility of our current electric grid time and again is showcased in an unfavorable light. But what about the natural gas grid? It’s underground, fairly redundant, and so far has a decent reputation for reliability.
What are Natural Gas' flaws?The Federal Energy Regulatory Commission (FERC) and the North American Electric Reliability Council (NERC) commissioned and produced a report, titled "report on the Outages and Curtailments During the Southwest Cold Weather Event of February 1-5, 2011" after the Southwest Cold Weather Event of February 1-5, 2011. The potential deficiencies noted, in the natural gas grid, need to be addressed across the entire U.S., and not just in the Southwest.
Distance from Gas HeadsDistance is one of these flaws. The pipeline transmission system, aka the “interstate highway” for natural gas, consists of 220,000 miles of high-strength steel pipe, 20 inches to 42 inches in diameter. This pipe highway moves vast amounts of natural gas thousands of miles from producing regions to local natural gas utilities and sometimes directly to large users of natural gas. There are compressor stations every 75 to 100 miles to boost the pressure, that is lost due to the friction of gas moving through steel pipe. The Natural Gas pipeline network extends across the entire country.
Natural Gas' Reliance on Electrical GridAnother of the major flaws of Natural Gas grid is it's dependency on the electric grid. The gas grid relies on electricity. The gas grid requires that pressure must be maintained throughout the system. This pressure is maintained via a system of compressors and pumping stations. The good news is that some of the main compressor stations, feeding the large interstate pipelines, are typically fueled by natural gas and generate their power with it, to keep operations running. Gas-fueled compressors could be more widely used throughout the system, but they are noisy and have environmental implications. So in urban areas, the gas distribution companies typically use electric pumps and compressors to bring gas to the consumer. It’s not hard to see where the problem lies here. No electricity, no gas supply. If you are lucky enough to live along a line that is powered by it's own natural gas, you should still have some pressure pushing gas down the line, as long there are no breaks in the line.
Electrical Grid's Reliance on Natural GasThe electric grid relies on natural gas. In the U.S.A., natural gas powers almost a third of the electricity generation plants. With the discovery of enormous shale gas reserves and the low prices of natural gas, that number is growing quickly. Almost all new conventional electrical generation on the books in the USA is natural gas-fired.
Cold WeatherThere are also vulnerabilities pertaining to gas service, especially during extremely cold weather. These weather issues start in the field where the gas is collected from wells and routed into the feeder pipeline system. This process can be disrupted by ‘freeze-offs’. Freeze-offs occur when water that is co-produced with methane, crystallizes or freezes, blocking the gas flow and shutting wells. “Freeze-offs" routinely occur in cold weather. Too many freeze-offs can result in a loss of pressure to the pipeline. If the pressure gets too low, the distribution companies start cutting off customers to maintain adequate pressure. They first curtail service to marginal areas most likely to fail, and simply shut meters. Unlike the electric grid, which can be restored fairly quickly, once the main problems are fixed, gas restoration is a slow process.
- Teams must close all the meters,
- Purge the system with air
- Re-pressurize with gas
- Teams must visit every location to relight pilot lights and ensure safety.