At Arcadia Power, we connect members to wind and solar power. When we mention renewable energy, there are normally many different types that come to mind. That’s because the earth provides many natural energy sources we can leverage, such as water, wind, sun, biological material and the planet’s natural internal heat. What’s crucial to be aware of is that there are pros and cons of every form of energy, even if they are all sourced from renewable resources.

Hydropower

Hydroelectric plants have been operational in the U.S. since the 1880’s. Large hydroelectric reservoirs such as the Three Gorges Dam in China are still popular in countries around the world.

The concept behind hydropower is nearly identical to that of wind power. It’s all about movement – kinetic energy. Moving water presses against turbines that spin a generator and create electricity. Water is much denser than air, so even a slow-moving stream can generate significant amounts of energy. Hydro turbines have to be more rugged than wind turbines and therefore they cost more to produce. However, they can also capture more energy than wind turbines of the same size.

According to the U.S. Energy Information Association (EIA), hydropower is the largest renewable energy source in the U.S. As of 2016, about 6.5% of our country’s total electricity came from hydropower, and 44% of all renewable energy was hydro. About 70% of the world’s renewable energy is hydro. China is the world’s biggest hydroelectricity producer.

Although hydropower uses water to produce energy, it can be highly destructive. Many hydropower plants require damming, which requires a good amount of land. This causes many communities, both human and wildlife alike, to relocate.

Tidal Power

The forces of gravity and the Earth’s rotation cause water movement every day, up and down the world’s sea coasts. In some places, tidal water moves back and forth as much as 40 feet. Europeans started harvesting tidal energy more than a thousand years ago.

Tidal power’s version of a dam is called a barrage. It’s installed across the mouth of a bay or tidal basin. The basin fills when the tide is high, and then empties through an electrical turbine system as the tide flows out. Energy can be collected from the tide both coming and going.

Unfortunately, tidal power stations can have a negative effect on the ecological systems that thrive along the coasts. Because the technology has to be built close to shore, it can disrupt the ecosystems close to and right below the surface. However, scientists are working on technology that can generate energy further out at sea with much less ecological damage.

Wave Power

If you’ve ever been batted around by the surf when swimming in the ocean, you know how powerful waves can be. The EIA estimates that waves off the U.S. coasts could theoretically generate as much as 2.64 trillion kilowatt-hours of electricity every year. That’s approximately 65% of the country’s entire power generation.

For more on wave and ocean power, check out The U.S. Department of Energy’s Marine and Hydrokinetic Technology Database or the Ocean Renewable Power Company, which is conducting testing and demonstrations of a wave power project at Cobscook Bay in Maine.

Because this is a fairly new technology, the potential negative impacts have yet to be evaluated.

Geothermal

Did you know the Earth’s core is hotter than the surface of the sun? That’s a lot of heat. And heat means energy.

The heat produced deep inside the Earth’s core – which can exceed 9,000° – is continuously generated as radioactive particles in the core slowly decay. The heat at the core melts the surrounding rock, forming magma. Magma is lighter than solid rock so as it moves upward it heats the rock and water in the Earth’s crust.

Hundreds of thousands of years ago, Romans were using geothermal energy to heat bathing water. Today, people drill wells in the Earth’s crust to access the piping hot steam or water for power. The deeper you go, the hotter the water. Geothermal power plants are generally built near geothermal reservoirs lying within a mile or two of the surface. Geothermal heat pumps transfer heat from the ground into buildings during the winter and reverse the process in the summer.

In 2016, the U.S. led the world in geothermal electricity production at about 17.4 billion kilowatt-hours. The Philippines and Kenya are also notable geothermal power producers.

Unfortunately, accessing geothermal energy is highly destructive. Deep drilling, sometimes hundreds of miles below the surface, is required to reach the hot steam. This can create permanent damage both on and below the earth’s surface.

Biomass

Biomass is organic material generated by any living thing: namely plants and animals. But the original source of that organic energy is the sun.

You probably remember learning about photosynthesis in Biology class. Plants capture the sun’s energy and can release it as heat after they die. Fuel can be created by burning tons of expended plant life (biomass). Think of all the waste material you might find at a lumber yard or a farm. That sawdust and wheat chaff is actually biomass, which can be collected to generate heat or electricity.

Other biomass processes include fermenting crops such as corn and sugar cane to produce fuel ethanol. Biodiesel, another transportation fuel, is produced from vegetable oils and animal fats. Even barnyard manure can be converted to something called biogas, which is a type of fuel. Biogas can also be created when certain bacteria break down organic material via anaerobic digestion. Much of the garbage we throw away every day is biomass – scraps of food, or debris from our yard.

As of 2016, biomass fuels provided about 5% of our country’s energy. About 48% of that was from biofuels (mainly ethanol), 41% from wood, and about 11% from municipal waste.

Biomass as a renewable energy is still a controversial approach, requiring further research and development. Biomass can lead to deforestation given a good amount of wood and debris must be burned. Also, because you have to burn biomass for energy, it is not technically “clean” or carbon free.

Although there are many forms of renewable energy, some are better than others, so it’s important to stay informed. Wind and solar are the least destructive on the environment but the world is full of renewable, clean energy choices – and the future of energy is heading in that direction,

For more information on wind and solar power visit our blogs What Kind of Solar Power Is Right For You? and What It’s Like To Be Inside A Wind Turbine