In Perspective

Natural Gas, Closer to Home

Over the last couple of weeks we have been talking about power generation mostly focusing on the fuel to generate that power. The world's power demands are expected to rise 60% by 2030 making energy production a hot topic. So, this week let’s talk about natural gas - NG. It is hard to put gas into perspective since it is measured in billions and trillions of cubic feet. The U.S. produces about 18.6 trillion cubic feet of gas yearly which is more than 10 cubic miles of gas and it is estimated, in 2003, that we had reserves of 1,338 trillion cubic feet of gas. So at the current rate of use we have a 65-year supply.

Of course the demand for natural gas has tripled in the last 50 years and it is expected that some of the coal-fired plants will be replaced by natural gas fired plants. There is also the call for vehicles to use natural gas as a fuel. Why is this important? The cost of NG was about $40 / thousand cubic meters in 1959 and is close to $280 / thousand cubic meters in 2008 and increase of seven times.

Already the U.S. imports about a 1/3 of its natural gas, mostly from Canada. But, to keep up with the demand, the U.S. liquefied natural gas (LNG) terminals are being proposed, to enable increased imports. This will again leave us vulnerable to foreign countries and higher deficits. Fifteen nations account for 84% of the worldwide production of natural gas and this is a significant factor in international economics and politics.

Gas production has its problems, also. After the natural gas is extracted from the ground, it is treated at gas plants to remove impurities such as hydrogen sulfide, helium, carbon dioxide, hydrocarbons, and moisture. The New York State Department of Environmental Conservation analyzed wastewater from drilling and found that they contain levels of radium 226, a derivative of uranium, as high as 267 times above the limit for discharge into the environment and thousands of times higher than the limit safe for people to drink. This is all suppose to be treated at a plant and then released into the rivers. Of course, little has been mentioned as to what becomes of the waste from the plant and nothing about the radium. In the past a problem like this was just diluted to show lower numbers, but long term effects have not been studied.

Another issue that is always related to NG is how clean it is, but that is only when they compare it to oil and coal. Compared to the average air emissions from coal-fired generation, natural gas produces half as much carbon dioxide, less than a third as much nitrogen oxides, and one percent as much sulfur oxides at the power plant but does not have the coal ash and slurry problems of coal. But when it comes to efficiency the basic NG plant is no better than the 33% efficiency of a coal plant. So engineers have developed a combined-cycle plant. The combined-cycle plant uses a gas turbine to generate electricity and then the exhaust gases are used to create steam generating electricity of a typical power plant. The combined-cycle plants are much more efficient than regular steam units or gas turbines alone and can achieve thermal efficiencies of up to 50 to 60 percent.

Unburned natural gas, mostly made up of methane is 20 times more potent than carbon dioxide as a greenhouse gas. Leaks can be deadly to the environment as well as human life. What should be mentioned, and has been in the news recently, is the explosive power of natural gas. Houses have been leveled and craters have been created due to gas leak explosions. Though it isn’t a common occurrence, the increase in production, storage, transportation and usage of natural gas creates an increased possibility of more explosions.

http://en.wikipedia.org/wiki/Natural_gas

http://www.scientificamerican.com/article.cfm?id=marcellus-shale-natural-gas-drilling-radioactive-wastewater

http://www.eia.doe.gov/oil_gas/natural_gas/info_glance/natural_gas.html

http://www.energyjustice.net/naturalgas/