Renewable Energy Guide
Renewable energy, or green energy, is generally defined as coming from resources that can be replenished naturally. This includes sunlight, wind, rain, tides, waves, biomass and geothermal heat. Additionally, these sources release very little or no greenhouse gasses and chemicals associated with energy production from fossil fuels such as coal and natural gas. According to the U.S. Energy Information Administration, about 19 percent of the world's generated electricity is from renewable energy sources, and is projected to grow to 23 percent by 2035. Here is a breakdown of a few of the most popular renewable energy sources.
According to the U.S. Department of Energy, more than 173,000 terawatts of solar energy strike the Earth continuously, making it the most abundant energy resource available. This totals more than 10,000 times the world's total energy use. Solar energy can be converted into electricity in two ways: photovoltaic devices, such as solar panels, or solar thermal electric power plants such as the Ivanpah solar facility in the Mojave Desert in California.
One of the largest obstacles facing the solar energy industry is the cost of the technology. While the price of items such as solar panels has rapidly dropped, it has yet to reach a comparable level to electricity generated by fossil fuels. One of the many benefits of solar energy is that solar panels can be added to parts of buildings, minimizing the amount of land needed for energy generation. The solar power industry is limited by the inconsistent output of sunlight throughout the day, requiring energy storage units to be created to ensure energy is available on cloudy days and at night.
If you've been on a road trip in the past few years, you've probably noticed a growing number of wind turbines popping up across the United States. As an alternative to fossil fuels, wind power is not only a clean and unlimited resource, it produces no greenhouse gas emissions during operations and requires little land. As of 2011, Denmark is generating more than a quarter of its electricity from wind. On a day to day basis, wind appears to be very inconsistent. It is very difficult to depend on an inconsistent source of energy. However, when projected over longer time windows such as one year, wind is very consistent. With the development of some energy storage systems, wind energy can be generated and stored in very reliable and consistent amounts.
Though wind power has no fuel costs, it is an expensive method of energy generation. Building wind power facilities is expensive, but engineering improvements have made the machines more efficient and cost effective. Additionally, the wind power industry has faced criticism for its impact on local bird and bat populations, though the overall impact on these populations is hotly contested. Although bird deaths can be related to a number of manmade structures, wind power has had a significant effect on raptor species such as golden eagles, which live in the high wind speed areas that are now home to wind farms. These raptors are considered particularly precious by animal activist groups and are slow to reproduce.
When many people think of hydropower, they imagine a massive dam using the flow of a river to generate energy. In fact, recruiting flowing water to generate power is one of the oldest sources in human history. These facilities all follow the same principle – a turbine or similar mechanism is propelled by the flow of water, which ultimately starts a process of energy generation. Hydropower is particularly popular in Washington State, which derives about 66 percent of its electricity from water. Hydropower technology is rapidly evolving, and now is being applied to generate electricity from tidal flows at offshore sites in the Northeast and Pacific Northwest.
One of the major advantages of hydropower is that it is an inexpensive method of energy generation. Additionally, dams and tides have reliable power outputs, which is one of the major issues with other renewable energy sources. The common arguments against using hydropower are the high upfront costs of building the power systems and the environmental damage of building a dam or offshore energy structure.
Biomass & Biofuels
Organic material from living or recently living organisms can be burned to generate heat energy or converted into methane gas or biofuels such as ethanol. In 2012, biomass-based fuels fulfilled about 5 percent of the United States' energy needs. Of this, 45 percent was from wood-based biomass, 44 percent from biofuels and 11 percent from municipal waste. Using biomass for energy or fuel offers a practical alternative to our expanding landfills.
The use of biofuels is a strongly contested idea. Many individuals are concerned that farms will increase their production of crops for biofuels production, driving down supply of non-biofuel crops and causing prices to spike. Additionally, large-scale biofuel generation would require significant amounts of organic material, likely coming in the form of deforestation. Lastly, biofuel generation processes require significant quantities of water, from crop irrigation to boiling and cooling water at the refineries.
Geothermal energy is recruited by digging deep wells underground and pumping the heated underground water or steam to the surface. The United States is the world's leader in geothermal power electricity generation, and produced about 17 billion kilowatt hours in 2012. It is used in electricity power plants and commercial and residential direct heating systems. The most active geothermal resources are usually found along major plate boundaries, particularly on continents that border the Pacific Ocean.
Geothermal power plants release less than 1 percent of the carbon dioxide emissions and 97 percent less sulfur compounds than a fossil fuel plant. After the steam and water have been used, they are injected back into the earth. Geothermal technology is limited by the upfront costs of the infrastructure, and that the ideal geothermal power sources are very location-specific.
In 2012, about 12% of U.S. electricity was generated from renewable sources. While this percentage is still very low, it is steadily increasing, helping to reduce America's environmental impact and increase its energy independence. The dependence of renewable energy is largely limited by upfront expenses and the inconsistent nature of many of these energy sources. Ultimately, until energy storage systems are more popular, our dependence on coal and natural gas will remain high.