Thermal Power - A Hot Topic on Alternative Energy
When people talk about the need to use alternative energy, they often cite thermal power plants as damaging the planet. The thing that they tend to exclude is the 'thermal' part refers to the process of generating the energy, not the fuel going in to the process, or the waste products coming out of it; some thermal power plants do the environment no harm at all.
The process works something like this: a fuel is used to heat water to a point where it becomes steam. The thermal power plants use the steam to power a steam turbine in much the same way as the old steam locomotives used it to power a piston, but instead of giving forward momentum, it powers the electrical generator.
The variations in the process really come in how they create the steam, and the waste products produced. Many will recycle the water that's collected in the condensers, by sending it back to the boiler where it is reheated and reused. Others will use the heat generated for their own heating purposes. As you can see, you can't pigeonhole all thermal power plants as being the same.
The type of thermal power plants that you'll hear of the most often are the fossil-fueled plants, and with very good reason. These plants have to burn fossil fuels to generate the heat to boil the water and create steam, and as anyone with a fossil fuel burning fire at home will know, there's always going to be smoke. Where does that smoke go? The same place as it would at home - straight up a chimney. These CO2 pollutants get in to the atmosphere and (allegedly) create the climate change that appears to be happening all around us today.
Thermal power plants are useable, because the theory is still sound, but it needs a different sort of fuel, which will eliminate the CO2 being pumped out in the process. This is where the solar thermal power plant and geo thermal power come in to the equation.
Solar thermal power plants do a very similar thing, but in a more environmentally friendly way. Instead of the solar thermal power plant burning a fossil fuel to heat the water etc, they use massive amounts of solar energy to heat the water. The biggest advantage of this is there is no smoke produced in the process; the big disadvantage is collecting the solar energy to start with.
Although it is possible to collect solar energy in places where there is little sunshine, most of the sites of solar thermal power plants are in areas where there is an abundance of sunshine hours each year. In these early stages, you need a large number of solar panels to collect enough solar energy to power the solar thermal power plants. This effectively means that, currently, the best place to have solar thermal power plants is large and desert-like locations.
As the technology improves, solar thermal power plants may become a more practical solution for other countries.
Geo thermal power has the advantage of being renewable, and the energy costs are relatively low. It has the disadvantage of being quite expensive to build initially; but it would eventually pay for itself.
Geo thermal power works in one of two ways. The first is to send 'dry' geothermal steam to a turbine, and the turbine powers the generator. The condensation goes to a condenser, which pumps the resulting water back in to the earth. The second type of geo thermal power uses flash steam. The system pulls hot water, under high-pressure, from deep in the earth. The next step is to pass the water in to a separator that will send steam to the turbine, and water back to the earth. As with the dry steam method, this system uses a condenser to return the remaining water back to the earth after it has been through the turbine.
There is a bit of a debate about the 'green credentials' of geo thermal power, however. Most people say that it's good for the environment because it's not burning fossil fuels, where as some, on the other hand, claim that it actually draws out gases from inside the earth, puts toxins back in to the ground, and it makes the surrounding land unstable.
As you can see, there are many variations on the theme of thermal power plants; so treating all of them as being the same polluting menace, would be a mistake. Solar thermal power plants are a good alternative, but not practical everywhere. The geo thermal power being generated worldwide makes up just a small percentage of what's required, and it may, or may not, have an adverse effect on the environment.
We may still have a long way to go to get the best solution for our power needs, but you shouldn't completely count out thermal power plants.