The Many Uses of Geothermal Energy

[00:00:02]Hi, my name is Christopher Katis and I work at the University of Utah on a research project called the Utah Frontier Observatory for Research in Geothermal Energy or Utah Forge. Today we're going to talk about geothermal energy, an important renewable energy source.

[00:00:23]So, what is geothermal? Well, the word geothermal comes from two Greek words. G or ye, like geo, which means earth, and thermos, like thermos, which means hot.

[00:00:36]Geothermal is literally the heat that is beneath our feet. And the deeper you go into the earth, the hotter it gets. In fact, the crust of the earth averages about 60° Fahrenheit. But just below that in the mantle, temperatures range between about 1,800 and 6,700°.

[00:00:57]But that's nothing compared to the outer core where temperatures can reach upwards of around 8,100° F. And the inner core where there is radioactive decay from radium, uranium, and thorium, the center of the Earth, you can find temperatures reaching about 9400° F.

[00:01:23]The Earth's crust is sort of like a big jigsaw puzzle. The tectonic plates are large pieces of crust that move on top of magma found in the upper mantle. They slide and collide against each other and they can also pull away from each other.

[00:01:38]All of this activity results in mountains, volcanoes, and earthquakes.

[00:01:46]Where plates collide and one is more dense or heavier than the other, the heavier one will sink under the lighter one that is more buoyant, so it floats.

[00:01:56]As the heavier one goes deeper, where it's hotter, it slides toward the mantle where it comes into contact with the magma. The rock breaks up and makes openings for magma to come to the surface and make volcanoes. When the two plates have the same density, they push up against each other and the plates crumble and fold upwards forming mountains. A great example of this is India crashing into Asia and creating the Himalayas where Mount Everest is.

[00:02:27]When the plates slide against each other going in opposite directions, they can get stuck. Eventually, that stress is released by the rock breaking or slipping. This sudden release of mechanical energy causes earthquakes. A plane of breakage or slippage is called a fault. You may have heard of the San Andreas fault in California, which is a very active fault on the Ring of Fire.

[00:02:52]It is the result of the Pacific plate moving north and the North American plate moving south.

[00:02:59]When two plates move apart from each other, they leave an opening that allows the magma to rise. Since it comes into contact with cooler ocean water, the magma becomes hard, creating new crust.

[00:03:18]The ring of fire is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. It stretches nearly 25,000 miles long from New Zealand up to Siberia in Russia across to Alaska and down to Chile. Although it's very long, the area of activity is only about 300 miles wide. The Ring of Fire contains approximately 1,000 volcanoes, about 2/3 of the world's total that have been active during the past 12,000 years. It is also home to 90% of the world's earthquakes.

[00:03:58]The heat beneath our feet is everywhere.

[00:04:02]And it's no coincidence that geothermal activity is found at plate boundaries and where there are or were volcanoes.

[00:04:11]Where two tectonic plates collide, they create cracks in the crust through which water heated by magma can escape to the surface.

[00:04:23]Below the surface we have a heat source like magma that provides energy in the form of heat. When it comes into contact with the surrounding rock there is a transfer of heat from that magma to the rock. What happens when you iron a shirt and you touch the shirt? You can feel the heat, right? That transfer of heat from the iron to the shirt is called conduction. When rainwater, snow melt or seaater seeps into the earth and comes into contact with the hot rock, the water heats up. Since earthquakes and magma movement have made cracks and openings in the earth's crust, that hot water can come to the surface and remain there as a natural geothermal system like a hotring. The water rising up to the surface and sometimes becoming steam is called convection.

[00:05:18]What does a natural geothermal system look like? Well, a natural system needs three parts: heat, water, and a pathway for the water to move through. Probably the most famous natural system in the world is in Yellowstone National Park in the western part of the US. Its geothermal features include hot springs, boiling mud pots, and of course, geysers like Old Faithful.

[00:05:52]Today, they're all protected as part of the world's oldest national park, so we can't use them for energy. But Native Americans who considered the area sacred use the geothermal waters in Yellowstone for cooking and ritual cleansing.

[00:06:08]In fact, humans have used the geothermal systems around them for at least 10,000 years. Middle stone age people used hot springs for warmth, cleaning and cooking. Ancient Romans, Chinese and Greeks used geothermal waters for therapeutic bathing, ancient hot tubs.

[00:06:26]And in Gokuani Monkey Park in Japan, the snow monkeys sit in the hot springs to keep warm in the winter.

[00:06:35]But they're not alone. Snakes are exothermic or coldblooded, so they have to use the sun to regulate their body temperatures. But in Tibet, in China, where we find the highest elevations in the world, the Tibetan hotspring snake has evolved to use its tongue to sense hotsprings and uses those to regulate its body temperatures. The Dixie Valley toad was discovered near Reno, Nevada in 2017. It was the first new toad found in America in 50 years and found nowhere else in the world. It doesn't burrow under ground to stay warm. Instead, it stays in warm springs its whole life.

[00:07:17]In Mexico, there's a pup fish that lives in water that's over 114° F. It's an example of an extreopil or an animal that can live in very harsh conditions.

[00:07:30]Living in those temperatures has earned it the nickname the world's hottest fish. If that's not hot enough, there's even a snail that lives in some hydrothermal vents at the bottom of the Indian Ocean where the temperatures are 750° F.

[00:07:47]They don't get boiled because they coat themselves with iron ions they take from the water to build their shells. They even cover their fleshy foot in thick metal plates like a knight's armor.

[00:08:00]Depending on the chemical makeup of the waters, they can be black, white, or even gold.

[00:08:08]Virtually everywhere in the world, there is a steady supply of milder heat at depths from anywhere from 10 to a few hundred feet below the surface. That heat can be used for direct heating and cooling called heat pumps where a fluid is used to push that heat into a building to warm it in the winter and then pulls the heat out of the building to keep it cool during the summer.

[00:08:32]Today, that heat from the earth is used in many different ways, including for growing fish, flowers, and vegetables, and for spas, heating and cooling, and sometimes even to melt snow.

[00:08:47]Even the ground below your own backyard or your school has enough heat to control the temperature in your home or other buildings in the community. The University of Utah's Gardener Commons building uses the energy found just a few hundred feet below the Earth to keep it warm in the winter and cool in the summer. There are 150 shallow wells under a soccer field that no one ever sees. Using geothermal energy saves a university $80,000 a year in energy bills. And this isn't new. The city of Boisee, Idaho, has been using geothermal energy to heat and cool its downtown buildings since 1892.

[00:09:28]And in Clamoth Falls, Oregon, they're using the Earth's heat to melt snow on the city's sidewalks.

[00:09:36]Aquaculture is farming in water. People use geothermal waters to grow fish like tilapia, trout, and proms. In Colorado, it's even used to save and rescue alligators.

[00:09:53]Green houses are kept nice and warm to grow flowers and vegetables all year long using geothermal heat. If you see a poinsettia at Christmas time or chrysanthemums around Memorial Day in stores, there's a good chance they were grown in nurseries that use geothermal heat, like the one in these photos near Newcastle, Utah.

[00:10:17]Can you guess which country in continental Europe grows the most bananas because they use geothermal energy?

[00:10:26]Iceland.

[00:10:28]Iceland uses the heat beneath our feet to keep green houses at the required temperatures to grow this yellow fruit.

[00:10:35]They're even working to save a species of banana that is at risk of going extinct in the wild.

[00:10:44]Remember when we talked about rainwater seeping into the earth and being heated up by hot rock? Well, if that hot water can't make its way to the surface through cracks, it ends up being trapped underground. By drilling geothermal wells in places where this hot water is found, we can harness the heat to produce electricity in geothermal power plants.

[00:11:09]So, how does geothermal heat generate electricity in power plants? First, the water flows up to the surface through a well and becomes steam. Next, the steam travels through a turbine to a cooling tower where it condenses and becomes water again. The change from steam back to water causes a drop in pressure which then turns a turbine. The turbine is connected to a generator that makes electricity. Finally, the cooled water is then pumped back into the ground where the earth heats it up and the process starts all over again.

[00:11:49]And guess what? We even generate electricity from geothermal resources here in Utah. All three power plants are located in Beaver County and together they produce enough electricity for about 66,000 homes. However, at this time that electricity doesn't stay in Utah. It's sent to Arizona and California.

[00:12:13]You may have heard of other sources of renewable energy like solar or wind and may have seen solar panels or windmills.

[00:12:21]Those are great sources of renewable energy. But solar only works when the sun is shining and windmills need the wind to blow. Unlike solar and wind, geothermal energy is available 24 hours a day, 7 days a week in all weather conditions.

[00:12:39]As we've learned, the Earth's heat can be turned into energy. And there are many advantages to geothermal energy.

[00:12:46]One is that it doesn't cause pollution.

[00:12:49]Also, since it comes from the very center of the Earth, it likely won't ever run out. And remember, it's always on. Even more important is the potential geothermal energy offers us. Scientists believe if we can get just 2% of the energy found between about two and six miles underground, we will have 2,000 times the energy used in the United States every year. And all that energy is clean, renewable, and available 247.

[00:13:24]And that's good news for Mother Earth.