Geothermal energy is an environmentally friendly, sustainable, and renewable source of thermal energy generated and stored in the Earth’s crust. This energy is derived from radioactive decay in materials originating from when the planet was first formed. The geothermal gradient, the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the planet’s surface.
Electricity can be generated by capturing this heat energy to vaporize liquids. The steam produced is then used to propel high efficiency turbines which in turn generate electricity. This method of capturing geothermal energy is referred to as a binary cycle and represents electricity generation in a vapor-dominated hydrothermal system.
Historically the effective capture of geothermal energy was limited to areas on the planet’s surface coinciding with tectonic plate boundaries. This situation however is no longer a limitation. With today’s sophisticated drilling technology, largely driven by the global hydrocarbon exploration and development industry, geothermal energy can be accessed from almost anywhere on the planet. Vancouver Island benefits from both these circumstances. Proximity to Western Canada’s mature natural resources industry translates to ready access to world class drilling technology while the geographic region sits astride the natural meeting of the Juan de Fuca, Pacific, and North American tectonic plates.
In thermodynamics a binary vapor cycle refers to a power cycle that is a combination of two cycles. One cycle in a high temperature region and the other in a lower temperature region. In the context of a geothermal energy production environment, a binary cycle power plant enables the use and optimization of what would otherwise be considered relatively cooler geothermal reservoirs. This is accomplished with the use of pumps to direct hot water from a geothermal well, through a heat exchanger, with the cooled water returned to the underground reservoir. A second conjoined cycle making use of a working or binary fluid with a low boiling point, typically butane or pentane hydrocarbon, directed at high pressure through the same heat exchanger is then flash vaporized and channeled through high efficiency turbines. The vapor exiting the turbines chamber is re-condensed by cold air (or water) radiators and re-cycled back through the heat exchanger.