by MonteQuest » Sun 26 Dec 2004, 12:34:22
$this->bbcode_second_pass_quote('frankthetank', 'I') don't know about others here, but i think using nat gas for electricity production is not wise. To me its greatest use is for heating/cooking. How much sense does it make to pipe it to a electricity producer, send it to a consumer, consumer uses it to heat up leftovers?
About the nat gas leakage. I live near(not close!) to a large nat gas pipe(pipes) and every time i walk past them(depending on the wind) you smell it(i know it doesnt have a smell/its the sulfer) and its obvious there is leakage, how much???
Frank,
I agree with you 100%. Consider for a moment how many energy transformations (increased entropy) take place to use natural gas to generate electricity:
Natural gas is used to heat water/to produce steam/the water is used to turn a turbine/the turbine spins a generator/the generator produces electricity/the electricity is sent to a step-up transformer/ it is converted to high voltage/ this is transferred over power lines to a substation/then sent to a step-down transformer/and finally transferred to your house/ where the light wiring (for ease of installation) losses even more energy. Every slash / bar represents energy being transferred from one form to another with a loss of available energy as dictated by the 2nd Law of Thermodynamics (entropy) at each point. These types of units, which use the high heat capacity of water to optimize thermal output, typically achieve 33 to 35 percent of thermal efficiency, meaning that about a third of the heat generated is converted into electrical energy. The two thirds of heat generated that is not used to produce electricity is exchanged with the environment surrounding the plant and is lost as far as function al work is concerned. If you have electric heat, hot water, or a cooktop, the efficiency just goes south, especially in the case of heating water--wasn't that what we started with?
The second traditional method for generating electricity from natural gas is the centralized gas turbines. Gas turbines do not utilize steam but instead turn the turbine with the hot gasses directly produced from combustion of natural gas. Since there is no need to wait for water to be converted to steam, the turbines begin turning as soon as heat is produced from the combustion process. This property lends gas turbines to primarily peak load production where quick electrical production is needed. The cost of this advantage over steam generation units is lowered thermal efficiency(massive decrease in EROEI). Natural gas is used widely in this peak load generation strategy due to its ability to be quickly and easily ignited. Again, a labor and time-saving utilization due to cheapness, that results in great thermodynamic waste.
Many of the new natural gas fired power plants are what are known as 'combined-cycle' units. In these types of generating facilities, there is both a gas turbine and a steam unit, all in one. The gas turbine operates in much the same way as a normal gas turbine, using the hot gases released from burning natural gas to turn a turbine and generate electricity. In combined-cycle plants, the waste heat from the gas-turbine process is directed towards generating steam, which is then used to generate electricity much like a steam unit. Because of this efficient use of the heat energy released from the natural gas, combined-cycle plants are much more efficient than steam units or gas turbines alone. In fact, combined-plants can achieve thermal efficiencies of up to 50 to 60 percent.
If we used natural gas at our home to heat water or cook, we would have only one conversion: gas to hot water or hot food. Whatever solutions we come up with must be focused on decentralization of energy production and point of use applicable to the available local energy. In some places direct heating of water by solar would make the most sense rather than natural gas.
Natural gas normally is non-toxic, tasteless, colorless and odorless. For safety, a scent known as--mercaptan--an acrid chemical, is added so that you will recognize it immediately, should there ever be a leak. Mercaptan makes natural gas smell like sulphur, or rotten eggs. I have no idea how much is loss into the atmosphere due to leakage.
A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel."