The geothermal resources of the earth are vast, clean and plentiful. Unlike most other renewable energy resources, geothermal energy is available throughout the year, has an inherent storage capability and is independent of weather conditions. Its storage capability makes it an ideal stabilizing energy, which can compensate for the fluctuating nature of other forms of renewable energy, originating from the sun or the wind.
How does it work?
The source of geothermal energy is the continuous heat flux flowing from the interior of the earth towards its surface. Geothermal power plants pipe hot water or steam through wells that sometimes reach deep down to reservoirs underground. The thermal energy is then converted into electricity using different technologies:
- Dry steam power plants extract very hot steam from reservoirs in the earth. The steam activates turbines that generate electricity.
- Geothermal flash steam power plants use water temperatures of a least 182 C and convert it to steam to drive generator turbines. When the steam cools, it condenses water which is injected back into the ground to be used again.
- Geothermal binary cycle power plants can use water temperature as low as 57 C. The thermal energy is used to heat a fluid that turns into steam at low temperatures. This steam is pushed through a turbine to generate electricity. The water never touches the fluid and is re-injected into the well, where it heats up again, closing the cycle.
New IEC standard for steam turbines
For the geothermal industry to continue to prosper, notably as a viable alternative to fossil fuels, the technology used must meet proper safety and performance benchmarks. IEC International Standards ensure that systems and devices employed are tested and meet the appropriate standards of quality and efficiency. IEC Technical Committee 5 develops specifications and standards for the rating and testing of steam turbines. In 2020, it released the second edition of a key standard specifying the requirements for steam turbines: IEC 60045-1, which now includes automation safety specifications. The standard can be used for geothermal steam turbines but also for turbines employed in concentrated solar power plants, another form of renewable energy.
Viable alternative to fossil fuels as a result of COVID-19
As the price of oil has come down to historically low levels during the COVID-19 pandemic, it is no longer covering the costs of drilling, etc…Many see this as an opportunity to encourage oil companies, which are already investing in renewable energies, to make the switch to geothermal energy.
“The overlap between geothermal and oil and gas is in exploring, drilling and production. With this comes expert understanding of the earth’s sub-surface. It takes expert knowledge to find the right spots to drill, how to drill, what equipment is needed, and how to use it. During the current crisis, many skilled workers in oil and gas drilling companies are on standby. These workers could be re-deployed to the geothermal sector,” says Marit Brommer, the Executive Director of the International Geothermal Association (IGA) in an interview on the REN21 site.
If oil companies do seize the opportunity to switch at least partly to geothermal energy, IEC International Standards are there to help.