03/05/2019 | News release | Distributed by Public on 03/05/2019 12:54
When it comes to energy, do you hear terms like 'clean,' 'renewable,' 'green' and 'carbon-free' used interchangeably? Are they really swappable, and what exactly do they each mean?
Bonneville Power Administration brings the Northwest region clean, renewable, carbon-free hydropower to fuel the region's homes and businesses. Learn more about these energy terms to see what makes each of them different.
Clean energy is an umbrella term that 'includes renewable energy, energy efficiency and efficient combined heat and power,' as defined by the U.S. Environmental Protection Agency. Clean energy can be used to describe the energy derived from renewable (non-depletable) resources, such as hydropower or wind, as well as the energy saved through increasing its efficiency , such as installing LED lighting, that utilizes energy which would have been wasted. Overall, 'clean energy' is a broad term that incorporates other terminology because it encompasses energy production and actions that aim to create a more sustainable environment.
Renewable energy is defined by the U.S. Energy Information Administration as 'energy from sources that are naturally replenishing but flow-limited. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time.' The most predominant renewable resources used to produce energy in the United States are wind, solar, hydropower, biomass (burning of organic material) and geothermal (heat produced within the earth). In addition, the EIA notes that 'renewable energy plays an important role in reducing greenhouse gas emissions. Using renewable energy can reduce the use of fossil fuels, which are major sources of U.S. carbon dioxide emissions.' However, many states have 'Renewable Portfolio Standards' that may define only a subset of the renewable resources listed above as eligible renewables. For example, existing hydropower is oftentimes not an eligible resource for meeting state renewable portfolio standards.
Carbon-free energy is any resource that does not produce carbon dioxide when generating energy. Almost all renewable (non-depletable) energy sources-such as wind, solar or hydropower-are considered carbon-free. There are a few exceptions according to the EIA, which considers the renewable resources grouped under biomass to be carbon-neutral, since despite releasing carbon dioxide upon burning, 'the plants that are the source of biomass capture nearly an equivalent amount of [carbon dioxide] through photosynthesis while they are growing.' Although not a renewable resource, nuclear energy is also classified as carbon-free due to the fact that energy is released through the splitting of atoms, or fission, rather than through the process of burning or combustion.
Green power, according to the EPA, 'is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit.' The EPA considers these renewables to make up the green power subsection: wind, solar, low-impact hydropower, geothermal and properly treated biomass and biogas. Overall, green power includes only renewable sources, but not all renewables resources fall under green power. For example, untreated biogas derived from landfills can produce a toxic mixture of greenhouse gases.