Part of the challenge that many people face when talking about renewables and public policy is a lack of knowledge about the vocabulary that is used to explain it. So in this article, we’ll give definitions for some of those terms and also discuss some developments in renewables to give those definitions helpful context.

2050 — 2050 has come up in more than one report as a date by which, if current trends continue, temperatures and sea levels could significantly rise. On a practical level, a year like 2050 also allows businesses, organizations, and governments a long enough runway to make necessary changes.

Carbon neutral — A carbon footprint is made up of everything that we do, from driving vehicles to powering homes. Carbon neutral simply means that the amount of carbon dioxide emitted into the atmosphere is offset by other means (like land restoration or tree planting, for example).

Carbon tax — This is a tax on fossil fuels that is based on the amount of carbon dioxide emissions. The stated goal of carbon taxes is the “stick” aspect of a “carrot and stick” approach to renewables.

Carbon removal — Relating to what was said earlier about carbon neutrality, carbon removal can help industries move towards carbon neutrality, using strategies like:

• Tree restoration
• Soil management
• Direct air capture (DAC) — technology that extracts carbon dioxide from the atmosphere and either stores it in deep geological formations or uses it for food processing or to make synthetic fuels
• Enhanced mineralization — also known as “enhanced weathering,” this process accelerates the speed at which various minerals absorb carbon dioxide from the atmosphere
• Enhanced root crops — if crops have more, deeper, and larger roots, more carbon can be stored in the soil
• Bioenergy with carbon capture and storage — also known as BECCS, this process extracts bioenergy from biomass and captures and stores the carbon
• Ocean-based carbon removal — there are two different approaches here: 1. Abiotic approaches convert dissolved carbon dioxide into carbonates and bicarbonates or move carbon dioxide-rich surface waters to the deep ocean, and 2. Biotic approaches include upwelling nutrient-rich waters, seaweed cultivation, and protecting blue carbon stock (the carbon stored in coastal and marine ecosystems)

De-carbonization — Unlike carbon neutrality, de-carbonization seeks to remove carbon from energy systems entirely. It has a large scope, as power grids and supply chains can be de-carbonized.

Greenhouse gases — Many people know that greenhouse gases (GHGs) exist, but they may only be vaguely familiar with what those GHGs are: water vapor, carbon dioxide, tropospheric ozone, nitrous oxide, methane, and CFCs.

Net Zero — Similar to carbon neutrality in that it’s a math equation aimed at zero, net zero is frequently used when discussing national and international policy.

Biogas — A gas produced by a process called methanization that contains methane and carbon dioxide. Methanization ferments biomass in an oxygen-free environment.

Biomass — This refers to all organic matter that can be used to generate electricity, be transformed into fuel, or used directly to produce heat. It is found in urban and industrial waste, energy crops, biological wastes (from agriculture and livestock, for example), and residues (such as dead trees and foliage). Biomass is used as a fuel to create steam that powers steam turbine generators. It can also help to make ethanol and biodiesel.

Geothermal energy — This energy is deep below the earth’s surface and can be used to produce energy. It is an “always on” resource that emits little to no GHGs.

Hydropower — Electricity created via the turning of turbines via the flow of energy. Hydropower is often referred to as the world’s largest source of renewable energy.

Solar energy — As with GHGs, many people know about solar energy, but not precisely how it works. Solar energy can be captured in various ways. Two of them include:

• Solar collectors: these convert the sun’s radiation into heat. This heat is then distributed in a closed system that uses water or air as the heat carrier.
• Photovoltaic cells: these convert solar energy into electrical power. That power is then used locally or fed into a grid or battery system.

Tidal energy — Tidal power makes use of the differential between low and high tides to generate electricity. Tidal power is predictable and carbon-free.

Wave energy — Like tidal energy, this uses movements in the ocean to generate electricity. Wave power is the kinetic and potential energy associated with ocean waves.

Wind energy — If you think about it, wind energy is another form of solar power. Wind is generated by the atmosphere being unevenly heated by the sun, irregularities in the earth’s surface, and the earth’s rotation. Wind energy is captured in wind turbines that can be located on or offshore. Offshore wind turbines are finished with special protectants to deal with saline winds and corrosion, but can use sea winds to generate large quantities of energy with no carbon dioxide emissions.

Watts — Although batteries are so integrated into our lives, and are becoming even more so as electric cars come online, many of us still struggle with what watts and kilowatts (kW) are. Simply put, they are a measure of demand for power. Over a period of time, the term hour is attached, as in kilowatt-hours (kWh), megawatt-hours (MWh), and gigawatt-hours (GWh). One megawatt is 1,000 kW and one gigawatt is 1,000 megawatts.

As we’ve mentioned in a previous article, households in developing countries use hundreds of kWh annually, while those in developed countries use thousands.

Green hydrogen is produced using the electrolysis of water. The electrolysis itself is powered by renewable sources (hence “green”). Unlike grey hydrogen, which is produced by steam reforming of natural gas (and comprises 95% of the market at the moment), green hydrogen has significantly lower carbon emissions. Green hydrogen is most attractive to economic sectors that are difficult to electrify, like heavy transport and steel.

Understanding the vocabulary of renewables is an important first step in having a meaningful public debate on power and energy in our future on this planet.

A final term worth knowing is “greenwashing,” which happens when a company spends more time and money marketing itself as environmentally friendly rather than on actually minimizing environmental impact. Such companies want to capitalize on heightened consumer awareness around environmental issues without actually making necessary changes.