When it comes to sustainable energy usage, we mainly consider the effects of different types of energy and personal accountability when consuming that energy. Sources of energy, although seemingly infinite, are in fact at risk of depletion, as with any other natural resource. In addition, certain forms of energy have negative impacts on our environment. Some examples of renewable energy sources -- meaning those that do not consume fossil fuels and produce little to no pollution - include solar, wind, geothermal, biomass and hydropower.

The benefits of energy conservation are two-fold. For businesses, energy conservation practices can reduce electricity bills while switching to renewable energy can qualify your business for federal tax credits. Furthermore, per a report by International Renewable Energy Agency (IRENA), renewable energy is on pace to be consistently cheaper than other energy options in the US by 2020. Sustainable energy usage can also drastically decrease your business’s carbon footprint. Because much of our current energy is sourced from burning fossil fuels, the more energy you use results in more burning of fossil fuels to meet the energy needs and more carbon dioxide emission into the atmosphere.

What are our main sources of energy?

The United States currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels are nonrenewable, that is, they draw on finite resources that will eventually dwindle or become too expensive or too environmentally damaging to retrieve. In contrast, the many types of renewable energy resources - such as wind and solar energy - are constantly replenished and will never run out.

What are renewable forms of energy?

The most common types of renewables are solar, wind, geothermal, biomass and hydropower. Nuclear energy and natural gas are also very common, but more controversial.

Solar power uses energy from the sun for heat and electricity. The solar panels that you see are photovoltaic (PV) cells. They turn sunlight into electricity by capturing the electrons from photons, which are particles of solar energy. Solar thermal energy uses sunlight to heat a liquid, and its steam powers a generator. The heat is usually concentrated by using reflectors that direct large amounts of light to one spot. Solar power does not pollute or emit carbon dioxide, and we will never run out of sunlight. Still, there are some drawbacks. The sun is not always shining, and the sun doesn’t provide much energy to one place; it is all spread out so technology to capture take up a lot of space. Furthermore, producing solar panels is expensive and can be harmful to the environment because the production of the component materials involves mining mountains.

Hydropower captures energy from the movement of water. The water makes the blades of a turbine spin when it flows past, and the turbine spins a generator that produces electricity. Using hydropower does not produce any pollutants or greenhouse gasses, so it is a clean energy source. Still, building hydropower plants often uses fossil fuels and creates pollution. Furthermore, dams can prevent fish from migrating or harm plants and animals, which changes the local ecosystem.

Geothermal energy uses the energy of the heat produced inside the Earth. The inside of the Earth is very hot because of the decay of radioactive particles in the rock. For geothermal energy, pipes are built far enough underground to access the heat produced inside the earth. Regular cold water is sent down, and it is heated up, so hot water with steam is brought back up. This can be used to heat buildings or to produce electricity. Geothermal is a clean and renewable source of energy, but geothermal energy cannot be used everywhere. The underground temperature varies in different areas and is highest near tectonic plate boundaries.

Using biomass as an energy source means using plants and animals to generate energy. Gas from landfills can also be captured and used for energy, although this usually does not trap all the gas that is produced and leads to potentially harmful gas escaping into the atmosphere. The bacteria that break down landfill waste produce methane, which we can burn for fuel. Burning garbage (municipal solid waste) also gives us energy and gets rid of garbage that would otherwise fill landfills. However, burning garbage also releases a lot of toxic chemicals, resulting in air pollution that harms both people and the environment.

Another form of energy that we use that is not renewable, but is cleaner than fossil fuels, is nuclear power. Nuclear power is the energy that is created when atoms are split, which is called fission. Nuclear power plants induce fission underwater, which leads to the release of energy in the form of heat, which boils the surrounding water. The steam then turns a turbine, which generates energy. Unlike renewable energy sources, nuclear energy alone can provide enough energy for the entire United States. Nuclear power plants primarily emit water vapor, making them much cleaner than energy plants that emit emit greenhouse gases or other harmful pollutants. However, nuclear power plants come with their own set of considerations. If the process is not completely controlled, then the plant may be a combustion risk. While waste products are minimal in nuclear power plants, they also tend to be radioactive. Radioactive nuclear waste must be stored safely and securely until the radioactive particles decay and become less harmful to both people and the environment.

Natural gas is a type of fuel that comes from the ground and is obtained using a process called hydraulic fracturing, or fracking. Fracking involves pumping water and other chemicals at a high pressure underground in order to release the natural gas that is contained below the surface. Natural gas is a clean-burning fuel. Extracting gas is less harmful to the environment than extracting oil and coal. However, fracking can introduce harmful toxins into the groundwater, which can contaminate local water sources and cause health problems. Waste fluid from fracking is also often left to evaporate, which allows for the release of pollutants into the atmosphere.

Renewable energy sources have stable energy prices, provide a continual source of energy, and are long lasting. The have low greenhouse gas emissions, have the potential for large scale job creation, and are typically low cost operations. However, there is not one single source of renewable energy (nuclear energy is not renewable) that alone is sufficient to replace all current energy sources. The renewable energy sources used by different cities or regions needs to be customized to those regions. For example, solar power is most efficiently used in regions that receive a lot of sunlight year round. Wind energy is best for regions with relatively reliable wind flows. In places that meet both these requirements, a combination of solar and wind energy plants can be used to ensure constant energy production. Since transporting energy also results in some energy loss, using local renewable energy sources, rather than energy that needs to be transported long distances, is important to maximize the efficiency with which energy is both collected and distributed to consumers.

What can consumers do about energy?

The city of Chicago has several basic suggestions for using energy more sustainably: