Alternative Method (Geothermal Energy)

Geothermal energy is a method for generating electricity that was first utilised when a power plant was made in 1904. Geothermal energy is similar to fossil fuel energy in that it creates steam to turn turbines, but the source of the steam is different. This diagram explains how geothermal energy works.

Original diagram courtesy of:www.petratherm.com.au/ hotrock/

There are some positives and negatives about geothermal energy.

Positives

·        Geothermal power stations do not take up much room, so there is not much impact on the environment. Sometimes geothermal power stations are even placed near farms and forests.

·        Once a geothermal power station is set up, the energy is almost free.

·        There is no pollution from geothermal energy, only steam.

·        Fuel isn’t necessary because the energy comes purely from hot rocks.  

Negatives

·        Dangerous substances may come up from underground, and can be difficult to dispose of.

·        The main difficulty with geothermal power plants is the positioning. There aren’t many areas that have a desirable rock type and depth.

·        Eventually, the rocks used will cool down so much that steam cannot be produced from them.

From our research, we have not found evidence of houses being powered by geothermal energy. This is because new power grids would most likely have to be made to incorporate geothermal energy. It would also only be effective in areas near geothermal power plants, and there are a number of requirements for the situation of a power plant.

Heating and cooling on the other hand is quite commonly powered by geothermal energy in houses, but not in the way that it is normally produced. Geothermal heating and cooling is produced by an object called a geothermal heat pump, or GHP. Houses can be heated by geothermal energy by having a system of pipes running around the house that contain hot water that is pumped by the GHP from the ground below.

In summer, houses can be cooled by discharging the heat inside the house back into the ground. An interesting by-product of this cooling is the fact that household water can be heated by the heat from the house.

The GHP initially costs more than traditional air-conditioning and heating but geothermal climate control is cheaper per month. It is approximately four times cheaper than traditional heating, cooling and water heating per month and the total cost will be smaller within ten years.

As a rule of thumb, the cost of a GHP unit is $2,500 per ton of house. The average weight of a house is three tons, which would make the GHP $7,500. Weight is a force that is determined by the mass of the object and the acceleration due to gravity of the area. The formula for weight is w = mg. (w-weight, m-mass and g-acceleration due to gravity). The weight of a three ton house is 3000 kilograms and the gravity on earth is 9.8ms^-2. The formula would now be 3000 = 9.8m or m = 3000/9.8 or m = 306.12 This means that the mass of the house is 306.12 kg.

Efficiency

The formula for efficiency is output divided by input multiplied by 100. The efficiency of a geothermal power plant varies from single digits to up to 20%. This is less efficient than a fossil fuel plant, but the environmental impacts of fossil fuels mean that they will not be available for as long as geothermal energy. The efficiency of geothermal energy used for domestic heating and cooling, however is much, much higher at 90%. Efficiency of fossil fuel domestic heating and cooling ranges between 70% and 80%.

Law of Conservation

If geothermal power plants were closed systems, these energy losses would not occur, because of the law of conservation, which states that in a closed system, energy cannot be destroyed or created, only transformed into other kinds of energy. Instead, the power plant would be 100% efficient.

Energy Transformation

The goal of steam turbines is to turn kinetic energy into mechanical energy. The moving steam is the kinetic energy and the end product, the electricity is the mechanical energy. This process is exactly the same for geothermal as it is for fossil fuels.