Renewable Energy

What Is Renewable Energy?

Renewable energy sources can be replenished in a short period of time. These abundant and sustainable energy sources can be used to curb our need for fossil fuels, thus reducing impact to humans, other species and their habitats.

America needs more and more energy every year, whether it is fuel to create electricity or fuel for our vehicles.  There is constant heted political debate regarding the best decision for our nation's energy security, whether or not we should drill offshore, in the Arctic National Wildlife Refuge, or in the Canadian Tarsands to help America become more energy independent.  While politicians debate over this issue, they lose sight of alternatives to oil, like wind, solar, geothermal and hydro power.  America will not be energy independent if all resources are used to exploit every last drop of oil on American soil.  

Why Don’t We Use More Renewable Energy?

In the past, low fossil fuel prices, especially for natural gas, have made it difficult for renewable fuels to compete. The use of renewable sources is also limited by the fact that they are not always available.  

For example, cloudy days reduce solar energy; calm days mean no wind blows to drive wind turbines; droughts reduce water availability to produce hydroelectricity.  

The production and use of renewable fuels has grown more quickly in recent years due to higher prices for oil and natural gas, and a number of State and Federal Government incentives, including the Energy Policy Acts of 2002 and 2005. The use of renewable fuels is expected to continue to grow over the next 30 years, although we will still rely on non-renewable fuels to meet most of our energy needs.

Biomass:  Energy From Plant and Animal Matter

Biomass is organic material that contains stored energy from the sun. Plants acquire it through photsynthesis and then we can use that for anything from fertilizer to biofuels for a car that runs on bio diesel.   

Scientists consider biomass a renewable energy source because we can always grow more trees and crops, and waste will always exist. Some examples of biomass fuels are wood, crops, manure, and some garbage.

One large potential source of biomass in Colorado is the pine beetle kill.  You can't drive/hike/board/ski through the Colorado mountains without noticing the acres of standing dead trees. The mountain pine beetle leaves stands of brown trees in its wake.  The beetle populations have  exploded as a result of warmer winters and competition for water.  However, they might be a silver lining as Xcel is currently seeking bids for a biomass power plant using beetle kill wood. Learn more about the pine beetle from the National Park Service.

Solar:  Energy From the Sun

The sun has produced energy for billions of years.  Solar energy is the sun’s rays (solar radiation) that reach the earth.  Solar energy can be captured and converted into other forms of energy, such as heat and electricity.  In the 1830s, the British astronomer John Herschel used a solar thermal collector box (a device that absorbs sunlight to collect heat) to cook food during an expedition to Africa. Today, people use the sun's energy for lots of things, including generating electricity on-campus at CU.

 Solar energy can be converted to electricity in two ways:

  • Photovoltaic (PV devices) or “solar cells” – change sunlight directly into electricity. PV systems are often used in remote locations that are not connected to the electric grid.  They are also used to power watches, calculators, and lighted road signs.
  • Solar Power Plants -  indirectly generate electricity when the heat from solar thermal collectors is used to heat a fluid which produces steam that is used to power generators.

Learn more about Solar

Hydropower: Energy From Moving Water

Of the renewable energy sources that generate electricity, hydropower is the most often used. It accounted for 3% of total U.S. electricity generation and 35% of generation from renewables in 2011.

Through the use of large dams we are able to harness the power of rivers and moving water.  Dams are good for two things, creating electricity and creating reservoirs for drinking water.  Water is relased in increments from the reservoir into the river and as it moves through the dam it spins turbines which create electricity.  

These dams do have their own drawbacks though.  Impeeding the natural flow of a river causes widespread ecological damage, affecting the migration and habitat of countless aquatic species.  The change in river flow can lead to serious problems with errosion and sediment depletion.  Read about some of the impacts of dams on Colorado rivers in the LA Times article titled, Colorado river dams decimate native fish.

Learn more about Hydropower

Geothermal: Energy Inside the Earth

The word geothermal comes from the Greek words geo (earth) and therme (heat). So, geothermal energy is heat from within the earth. We can use the steam and hot water produced inside the earth to heat buildings or generate electricity. Because the water is replenished by rainfall and the heat is continuously produced inside the earth, geothermal energy is considered a renewable energy source.

Geothermal power today supplies less than 1% of the world's energy in 2009 needs but it is expected to supply 10-20% of world's energy requirement by 2050. Geothermal power plants today are operating in about 20 countries which are actively visited by earthquakes and volcanoes.


Learn more about Geothermal