What are The Environment Impacts of Geothermal Energy

What are The Environment Impacts of Geothermal Energy. Another source of energy called geothermal energy. Geothermal energy is one kind of thermal energy which stored in the Earth. Thermal energy is the energy that has affiliated to its temperature. The geothermal energy has been used since ancient Roman times for space heating and since Paleolithic times for bathing, but today geothermal energy is used to generate the electricity. In 2013, 11,700 MW of geothermal power is online around the world. Meanwhile 28 gigawatts of direct geothermal heating is utilized for spas, space heating, district heating, desalination, agricultural and industrial processes.

It is environmentally friendly, cost effective, sustainable and reliable for using geothermal power. Historically it has been limited to near tectonic plate areas. Nowadays, the geothermal technology has expanded the size and range of viable resources, particularly for applications like home heating, opening a prospect for widespread exploitation. The wells of geothermal release greenhouse gases that trapped deep in the earth, but compare with fossil fuels the emissions of geothermal energy per energy unit are much lower. Because of that, the geothermal power is potential resource to help mitigate the global warming if widely deployed in fossil fuels place.

Theoretically, geothermal resources are more than enough to supply energy needs for human, but only a very small portion may be advantageous exploited. It is very expensive to explore and drill from deep resources. Future predictions of geothermal power depend on energy prices, assumptions about technology, interest rates and subsidies. EWEB's customer opt in Green Power Program as pilot programs expose that peoples would be willing to pay more for a renewable source like geothermal energy.

What are The Environment Impacts of Geothermal Energy

What are The Environment Impacts of Geothermal Energy?

1. Water Consumption and Its Quality

2. Emissions into the Athmosphere

3. Land Use and Subsidence

 

Water Consumption and Its Quality

The geothermal power plants could give impacts to water consumption and quality. Hot water that pumped from below the surface of the earth reservoirs frequently contains highly salt, sulfur and other minerals. Commonly geothermal power plant facilities utilized closed-loop water systems, that extracted water is directly pumped back into geothermal reservoir after it has been accustomed for electricity or heat purpose.

Fluids of geothermal contain higher levels of boron, mercury, lithium and arsenic because of the contact between rocks and hot fluids in the underground. Whenever these materials are released into lakes or rivers instead of being injected or pumped into geothermal field, it can harm aquatic life and will make water unsafe for irrigation or drinking.

Arsenic pollution is a serious environmental impact of geothermal industry. In the Waikato River, arsenic levels almost constantly exceed standard of World Health Organisation (WHO) for drinking water of 0.01 ppm (parts per million). Large of quantity arsenic release from waste water discharged from geothermal Wairākei power station. The hot springs as a natural feature also an arsenic source, but it could be removed from water as colourful mineral precipitates such as yellowy green orpiment and bright red realgar.

Water is used for cooling and re-injection by geothermal power plants. All geothermal power facilities in the US utilized wet-recirculating technology for cooling process with the cooling towers. The geothermal plant can need between 1,700 to 4,000 gallons of water per MWH (megawatt-hour). Commonly, many geothermal plants can use either freshwater or geothermal fluid for cooling. The use of geothermal fluids instead of freshwater clearly reduces water impact of the plants.

In order to prevent land subsidence and contamination, almost all geothermal plants inject water again into the reservoir. In most cases, because some water become into steam, it has to used the outside water to keep a constant water quantity in the reservoir. The water quantity required depends on the technology and plant size. 

Emissions into The Atmosphere

Some dissolved gas that released into the atmosphere are contained by geothermal fluids. The dominant toxic gases are hydrogen sulfide (H2S) and carbon dioxide (CO2). These gasses are denser than air and can find in pits or confined spaces. The hydrogen sulfide and carbon dioxide are recognized as hazard gas for people working at bore fields, geothermal stations and in urban areas. A number of deaths in Rotorua have been affected by poisoning of hydrogen sulfide, often in hot-pool enclosures or motel rooms. Meanwhile, the carbon dioxide as a greenhouse gas is potentially causing climate change. However, compared with coal and gas as burning fossil fuels to generate electricity, the geothermal plant releases fewer emission gases per unit of electricity produced.

The main different between closed and open-loop systems is the respect to the air emissions. The open-loop systems emit carbon dioxide, hydrogen sulfide, ammonia, boron  and methane. Meanwhile in closed-loop systems, gases that removed from inside the well are re-injected into the underground after using so it is not exposed into the atmosphere. Because of that, the air emissions are minimal..

Hydrogen sulfide in the atmosphere will changes into sulfur dioxide which is contributes to the small acidic particulates formation that could be absorbed by bloodstream and cause lung and heart disease. Beside that, the sulfur dioxide can causes acid rain that damages soils, crops and forests. But, compared with coal plants, approximately emissions of hydrogen sulfide from geothermal plants are lower 30 times per MWH (megawatt-hour).

Any geothermal plants also release small quantity of mercury emissions, which have to be mitigated using the technology of mercury filter. Air emissions can be reduced by the scrubbers, but it produce a watery sludge composed materials, including silica compounds, sulfur, nickel, vanadium, arsenic, chlorides, mercury and other heavy metals.

Land Use and Subsidence

The land area needed by geothermal plant depend on power capacity, resource reservoir properties, energy conversion system type, cooling system type, piping systems, well arrangement, substation and needs of auxiliary building. The Geysers as the largest geothermal plant has a capacity about 1,517 megawatts in 78 square kilometers plant area, which explains to about 13 acres per megawatt. Because of geothermal plants location on geological, it have higher levels risk of earthquake. There is indication that hydrothermal plants can bring to a greater frequency of earthquake.

The land surface sinks phenomenon can caused by the remove water from the geothermal reservoirs. Almost all geothermal facilities prevent this risk by re-injecting wastewater into the geothermal reservoirs after its heat has been captured. 

In the Wairākei, where largest subsidence recorded, the subsidence bowl centre sinks almost half a metre each year. The sinks of ground sinks could move tilts and sideways towards the centre. Then, it puts a strain on pipelines and bores, and cause roads and buildings damage. The natural features like mud pools, hot springs, , geysers, sinter terraces, steaming ground and fumaroles (steam vents) and can be irreparably and easily damaged by development of geothermal power plant.

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