America leads the way!
America produces more energy from geothermal sources than any other country in the world. California has the largest group of geothermal energy plants in the world. “The Geysers” have over 700MW capacity.
23 countries generated 77 billion kWh of electricity in 2016 from geothermal sources. Kenya produced 44% of its total energy in this way.
Geothermal energy has some major advantages:
- Almost emission free
- Reliable – unlike wind or solar power
- Operates at a high capacity
- Not dependent upon the weather
How Earth Provides Heat for Us
When our planet was formed enormous amounts of heat were produced and retained by the earth. And as we go about our daily lives, every minute and every hour radioactive particles in the core of our earth decay and release more heat.
Our earth has four major layers:
1. Inner core – this iron core is around 1,500 miles in diameter
2. Outer core or magma, This layer of molten rock is about 1,500 miles thick
3. Lower and Upper mantles of rock and magma which surrounds the outer core and is about 1,800 miles thick
4. Crust -this is solid rock – 2-5 miles thick under the sea and 15-35 miles thick under the continents.
The temperatures depend largely upon how far you are from the core, which is as hot as the surface of the sun 10,800 degrees Fahrenheit. Then the mantle ranges in temperature from 7,230°F at the mantle-core boundary to around 392°F where it meets the crust. This causes the rocks and water underground to absorb the heat, and the deeper they are the hotter they are likely to be.
We experience places where the heat naturally escapes – erupting volcanoes, geysers, and hot springs.
Many of these places are at the edges of the tectonic plates, where we find most of our volcanos. Volcanos can erupt spewing out lava which flows down in boiling rivers, destroying all in its path.
Where we Get Geothermal Energy From
We can use the geothermal energy from near the surface – and, in addition, we can drill miles down to access the deeper, hotter areas.
In order to generate electricity, we need water or steam at temperatures of between 300F and 700F (150C-370C).
Chinese, Native Americans, Ancient Romans all used hot springs for bathing, and we can still enjoy the mineral-rich, soothing warm waters of spas around the world.
The geothermal energy within a mile or so of the surface can be accessed for heating, for electricity generation and geothermal pumps.
Enhance Geothermal Systems (EGS)
But, of course, we want the energy from the deeper hotter reservoirs and to do this we nor only have to drill deeper but we also fracture the impermeable rock to gain access to them.
Fracking and EGS
Fracking is a method of extraction that is used to harvest shale gas and is unrelated to geothermal energy production. It involves injecting fluids at high pressure, which consists of water, sand, and chemicals, into rocks containing shale gas. This forces cracks which allow the gas to be released.
Geothermal energy is gained by pumping warm water out of reservoirs and passing it through a heat exchanger. It does not involve having to break into geographic formations in the same way that fracking does when the heat is near the Surface.
But deeper EGS has caused some minor seismic disturbance and an EGS plant in Switzerland was closed in 2006 for this reason. However, this problem is rarely encountered, and the US Department of energy has produced a protocol to cope with this.
Where American Geothermal Plants are to be Found
The geothermal resources map shows the estimated subterranean temperatures at a depth of 6 kilometres (3.7 miles).
There are about 64 geothermal plants in the United States and 72% are in California. The western states have suitable ground and favorable policies – Nevada has around 22% and Utah 3%. Oregon, Idaho and New Mexico all use a small percentage of geothermal energy.
A Brief American History of Using Geothermal Energy
10,000 years ago the Paleo-Indians used the heat hot springs. Much later European settlers advanced across the continent. Finding ad using these hot springs for heat, for warmth, for washing. In 1807, the city appropriately named Hot Springs was founded – and the first known commercial transactions using geothermal energy were introduced – one Ada Thompson charged one dollar for use of a wooden tub fed by hot water springs.
Then in 1882, Idaho residents benefited from a hot water heating system, and in 1927 the first exploratory drills were carried out in California.
By 1960 the first large scale heat generating plant was operating at the Geysers in California. And now there are 63 facilities at 18 sites.
In the 1970s various laws were enacted and in 1977 the US Department of Energy (DOE) was formed.
The first geothermal food-processing (crop-drying) plant in Brady Hot Springs, Nevada, was opened, followed by Fenton Hill in New Mexico generating electricity in 1980.
California continued to advance its geothermal energy water resources: heating offices, and farm buildings.
TAD’s Enterprises of Nevada used geothermal energy for the cooking, distilling, and drying processes for alcohol fuels production in 1980, and Hawaii started to generate electricity from its volcanic heat resources.
At Roosevelt Hot Springs, Utah, A 20-MW plant began generating power. Nevada even used it to help in the extraction of gold and California continued to develop their resources. Washington was active in developing geothermal energy and in Texas in 1989, the world’s first hybrid (organic Rankine/gas engine) geopressure -geothermal power plant began operation at Pleasant Bayou. This uses methane as well as heat from a geopressured site.
A Special Mention of Hawaii
In 1959 Hawaii became the 50th state of the United States. And it consists of islands – these islands are the tops of volcanoes – and some of them are still active.
This means that although geothermal energy is readily available – there are risks from eruptions and lava flows. In fact, half of Hawaii’s power is petroleum based but geothermal energy supplies around 20%.
Since the year 2000
Then in 2005, the Energy Policy Act of 2005 became law. Tax incentives and loan guarantees became available, making fossil fuels less economically attractive. The Geothermal Technologies Office awarded $368.2 million to 149 geothermal projects in 38 states.
Over the next few years, the use of geothermal energy spread and diversified. In 2017, geothermal power plants in the United States generated around 16 billion kilowatt-hours (kWh). This is 0.4 % of the total electricity generated.
The Hawaiian Eruption
The plant had been producing almost 30% of the island’s power the previous year. Here hot fluid was bought up from 6000 -8000 feet, steam from the fluid under pressure drove the turbines to produce electricity. But in 2018, the Puna Geothermal Venture(PGV) power plant was shut down because of lava flows from the volcano Kilauea.
But not only do the lava flows damage the plants but also the transmission lines – as well as homes, requiring rerouting of power lines. You can see a report of the incident here.
Geothermal energy is a vast resource, available both near the surface and deep underground. It’s benefits have been recognized for thousands of years. California leads the way but there is the very slight problem of seismic activity (Not something welcome for this state) although guidelines are laid down by the government. Geothermal energy is almost emission and pollution free, reliable and gives a high return for the effort put in to extract it.
It is very effective and far less damaging to our environment than fossil fuels. This is one type of renewable energy where America really does lead the way.