There are some basic energy misconceptions in this thread
There are several ways to generate power with natural gas.
1.Convert an old steam boiler with an associated steam turbine from coal, oil or wood to natural gas. The overall efficiency of fuel to electric power with natural gas varies from lower with oil to somewhat higher than coal or wood. Overall at best 35% fuel to power efficiency. These plants take 8 to 12 hours to go from cold to full output and every time they are cycled on and off, the required maintenance goes up and reliability goes down. These used to be the base load power for the country. Unlike natural gas, when running on coal, oil or wood the owner buys the fuels in advance and stockpiles the fuel for use at a later date, they can run from day to weeks and are not dependent on limited pipeline capacity. Natural gas generates far less CO2 than fossil fuels so environmentally most regulatory bodies are strongly encouraging natural gas conversions
2. Burn natural gas in jet turbine with a generator on the shaft of the jet turbine. Send the hot exhaust gas from the turbine into the air . This configuration is called a "peaker". The efficiency is in the mid thirties up to forty percent. These plants are fast and cheap to build and don't take up much room. There are fleets of these that can be driven on site and can generate power in days. They are generally set up to burn liquid fuel (oil) in addition to natural gas. Their typical use is for short term temporary power. They can go from cold to full output in as little as five minutes. They generally are located near the load and have a large oil tank next to them so that they can start immediately in an emergency, they cant run on natural gas very often as in order to get large volumes of natural gas, the owner has to order it a day in advance. They are generally only used to balance out short term imbalances on the gird and for natural disasters. Unfortunately many of the mainstream renewables, like wind and solar are not reliable as they cannot stockpile wind or sun so the unfortunate side effect of renewables is a large fleet of new peakers.
3. The final way to burn natural gas for power only which is the vast majority of new generation in new England is with a combined cycle power plant. Natural gas is burned in one or more natural gas turbines which have generators hooked up to their shaft. The hot exhaust is then routed to a Heat Recovery Steam Generator (HRSG) and then the steam is routed to a steam turbine that can accept several pressures of steam. As the heat is being recovered, the turbines are optimized to burn at a very high combustion temperature and the overall fuel to power efficiency can be over 50%. These plants are the least cost to run and many can be run like a peaker if there is short term need for power. The efficiency goes up as the plant gets bigger so these are still very large capital intensive plants. One plant I worked on in Brampton Ontario was close to 1 billion dollars. In general they are quite flexible on output. The major downside is that these plants don't have a way of stockpiling natural gas so they are dependent on the gas line. On a day forward basis when there is more capacity in the pipelines, these combined cycle plants supply much of the power in New England but when the demand for power, heating and industrial use exceeds the pipeline capacity, something has to give. The residential heating customer pays a premium in the winter to guarantee that houses don't run out heat, so the industrial and power uses go into a bidding war for the gas capacity and the price of the gas skyrockets to the point where the combined cycle plants are no longer the cheapest option. In that case, any power plant that has a stockpile of fuel like a coal plant, biomass plant, ponded storage hydro or a peaker with big oil tank, can make a lot of money selling power at rates 10 to 20 times the normal rates and that gets factored in what everyone pays for power. The system is lot more complex than this simple explanation but this is rough approximation.
4. There is fourth option that industry uses that is the most efficient. Its called Combined Heat and Power. Industrial users like papermills need both power and steam to run their processes. In most large operations, the owner has a high pressure boiler and then generates some power by running the high pressure steam through a backpressure steam turbine which acts in place of a pressure reducing valve and then the process uses the resulting low pressure steam. The efficiency calculation is now bit more complex as there is one fuel input divided by the combination of the electric power produced and the thermal value of the steam. The efficiency can vary significantly but is almost always better than buying power and just generating steam. This process has been improved substantially by replacing the boiler with a gas turbine. It can be even more efficient than even a combined cycle as the fuel is used three ways, the turbine generates power, the resultant high pressure steam is run through a back pressure steam turbine and then the low pressure steam is used in the industrial process. The overall fuel efficiency of the plant can routinely be over 60%. In some densely populated areas in Europe (and a couple of US cities), there are district heating systems and regulations in place where even fairly low temperature hot water can be used for building heat and the overall efficiency can be even higher.
By the way, the overall efficiency of any thermal system is governed by the Carnot Cycle
http://en.wikipedia.org/wiki/Carnot_cycle. The difference between the highest temp in the system and the lowest temp sets the maximum efficiency. Gas turbines produce the highest combustion temperatures so any cycle with a gas turbine has the potential for the highest efficiency if there is a use for the heat left over.
The other power generation on the rise in the news is hydro. There are two types of hydro electric (note Canadians confuse things as they refer to any power plant be it hydroelectric, natural gas, wood or coal as "hydro"). The large hydros tend to be ponded storage where there is a big lake upstream of the dam. The operator stores water until power is needed and they then start draining the storage. That's great for power production but not great for the animals and ecosystem in the upstream lake. These plants flood a lot of land and are extremely costly to build so unless the government subsidizes the construction it is costly and in the US there are very few large hydros being built. The last major project in New England was the Dickey Lincoln project canceled 30 years ago. There are also run of the river hydros where there is no storage, these produce power when the water flows but are somewhat predictable. They are a small but important part of the regions power but due to environmental issues many are being removed. Folks hear about Hydro Quebec with its offer to sell New England all the power we want. Even though the ratepayers in Quebec pay very low rates, the power sold to the US will not be so low. The Quebec ratepayers are paying for existing hydro plants that were built with heavy direct and indirect subsidies. The new hydro offered to the US is from new plants that would be built without as many subsidies and the Quebec ratepayers expect some of the profits will be used to reduce their rates. It is convenient for New England as it is "Not In my Backyard" but this level of power transmission over very long distances has significant potential for grid interruptions so New England ratepayers will need to pay for a lot of backup generation in case the transmission system from Northern Quebec fails . This is not theoretical, a yahoo with a rifle knocked out the main line from Quebec two years ago for a couple of days and southern Quebec has experienced several major outages when the transmission system from Northern Quebec failed. This type of transmission is also significantly impacted by solar flares and hard to secure. The other current issue is that quebec has a rule in effect that if there is power shortage, they cut off exports. This has already happened when there was a severe cold stretch in Quebec, the utilities basically cut off power sales to New England. Therefore when we need to power most it may not be there.
I have left nuclear out as its probably not going to happen in New England anytime soon, the plants that are still running will continue until some point they are shut down but barring a major reduction in cost to build new plant and a major shift in the publics opinion I don't see any new ones going in.
The power grid is the most complex machine on the planet and to get a handle on it even its basics is something that most folks have no hope of understanding. Politicians, activists and wall street all know that and realize that by proper PR they can shift public opinion in any direction.
! You might as well send the electrons to China too
