Geothermal energy is a clean and renewable source of power, which has a number of environmental and economic advantages over traditional fossil fuel sources. This energy is commercially produced from naturally occurring steam and hot water trapped in reservoirs of permeable rocks below the earth's surface. Driven by climate change concerns, favourable government support and increasing energy consumption, what was once called “alternative energy” has now moved to the mainstream.

 

Throughout history, geothermal energy had been used for heating and bathing. Electricity from geothermal energy was first produced commercially in 1911 in Larderello, Italy. This facility expanded into major production in the 1930’s and continues to generate power to the present day.

Another notable geothermal system is the Geysers in California. This is the world’s largest complex of geothermal power plants, with the capacity to generate more than 1000 MW of electricity. The area has been producing electricity since 1960 and presently represents about 5 per cent of California’s electricity production.

Geothermal power plants produce long-term stable revenues and provide continuous base load power, often at or above 95% capacity. Depending on the size of the resource, geothermal power plants can be as small as 100 kW or as large as 100 MW.

Today, there are three different types of power plants used to convert hydrothermal fluids into electricity: dry steam, flash and binary. Dry steam plants operate on resources that are hot enough such that only steam is present in the reservoir. A flash plant operates on resources where there is hot water present. In a flash plant, hot liquid from the resource is turned to steam, or ‘flashed’, and then used to generate electricity. Below approximately 170°C (330°F), a binary power plant can more efficiently use the resource than a flash plant.

SGP anticipates that binary power plants will be the most suitable technology for the majority of our projects.

• A geothermal resource is identified through drilling in permeable zones of heated water.
• The geothermal reservoir fluid is pumped through a heat exchanger, where it heats a secondary working fluid with a lower boiling point.
• As the working fluid is vaporized, it drives the turbine.
• The turbine is connected to a generator that produces electricity.
• The working fluid is then condensed and re-circulated, forming a closed loop system.
• The geothermal reservoir fluid is injected back into the ground for recharge.

• Reliable, renewable and plentiful source of energy
• Combustion free with minimal environmental impact
• Binary geothermal facilities have near zero emissions
• Generates power without generating carbon dioxide

• Strengthens local economies by providing employment and tax/royalty revenues
• Reduces dependency on fossil fuel and foreign oil imports
• Diversifies power supplies
• Provides base load power that is immune to fuel price shocks