The Geysers

Hello Everyone,

This entry is devoted to a field trip I took with my energy resources class. The class focuses on providing a broad overview of where we get our energy and how it is created, and as part of the class, we are required to go on two field trips. The first field trip I went on was to the Geysers. The Geysers is located an hour or so drive north of San Francisco Bay (see map), and is the largest geothermal electric plant in the world (by quite a bit.)

Geothermal power is a sustainable green energy whereby the heat of the earth is harnessed. However, there needs to be a working fluid to transport the thermal energy of the earth which is usually water/steam. Since steam is a terrible conducting fluid for carrying heat, power stations must be located close to where the steam is brought up from under the ground. The result is that the Geysers is mostly a bunch of pipes containing steam that do not travel far to enter the power stations. In the following picture, you can see the pipes for steam and a power station (one of many at the Geysers) in the background.

Most of the Geyser power plants were built in the 1970s and the 1980s and production hit the peak in the late 1980s. At that time there were many different power companies operating in the Geysers, so they took out more steam than could be naturally replaced. Eventually, starting in the late 1980s, the steam pressure decreased which caused the electrical production to decline. The following picture is of the control panel in one of the power plants built in the 1980s, and as you can tell, it is not particularly computerized. Such equipment is very expensive to invest in, so it is installed to last quite some time.

The steam that is brought up from the ground is brought into the power station to a steam turbine just like the one below. The steam is pushed through the turbine, which turns, and eventually turns an electric magnet to create electricity. However, because of the lower steam pressure than when the plan was originally built, the steam turbine is out of the optimal pressure range it was built for, and does not collect the energy as efficiently as it could.

These are the cooling towers that the steam is sent to after losing its energy to the steam turbines. Since steam cannot be efficiently re-pressurized, it must be cooled into water, which is a very inefficient process. Not only is the thermal heat lost, but up to 60% of the steam evaporates and does not return as water. This stage is where the water is mostly lost. The remaining water that has been cooled is then re-injected into the steam reservoir.

There is a bright future for the Geysers. Almost all of the steam and power plants have been combined under one company, Calpine, such that they can plan for the future and not over withdraw the underground steam. In fact, Calpine has made agreements with local governments, in particular with Santa Rosa, to pipe their treated waste water to inject it into the steam reservoir. These new agreements has allowed the amount of water being injected to basically equal the amount of steam that is being evaporated. Although there are worries that injecting too much water would increase the potential for earthquakes in the seismically active area, so far the Geysers has successfully been able to inject the treated waste water (which also has the added benefit of being cleaner for the steam turbines than the normal groundwater.)

The Geysers is by far the largest geothermal plant in the world. Although it was able to produce around 1.5 GW at the peak in the late 1980s, the almost 1 GW it produces now is about equal to the geothermal electric capacity of Indonesia, the third largest producer of geothermal electricity (after the US and the Philippines.) Since it is the largest plant by far, it is an important example for other geothermal plants and countries looking at geothermal power.

The last picture is of me in front of the steam turbine and electric generator.


Another entry at some point (but probably not that soon due to finals),
-Andrew