Clean energy
Climate Change Daily Energy Repost Urban Environmentalist

Running our Cities on Clean Energy

But is it clean or just renewable?

Despite the many conversations and news reports about moving to clean energy, we still see confusion around the differences between clean energy and renewable energy. A recent article entitled “What Would It Take to Run a City on 100 Percent Clean Energy?” addresses the efforts by some U.S. cities to reduce their carbon footprint. The article does a great job of identifying key obstacles to carbon reduction, but it blurs the line between clean and renewable.

One of the examples given in the article is Burlington, Vermont’s claim they have reached an energy milestone by producing enough power from renewables to cover their electricity needs. This announcement is good news, and they have achieved an admirable milestone. Burlington reached this goal through benefiting from existing hydroelectric power supplies and “ample wood for biomass burning.” But there is a catch. While energy from biomass is renewable, it is not necessarily clean.

A forest fire burns trees (biomass), and we are hard-pressed to call the resulting smoke clean and carbon-free. Wood is part of the renewable biomass category, yet burning wood releases greenhouse gases into the atmosphere. Even though wood is a renewable energy source, it is also a dirty fuel source, releasing one and a half times more carbon than coal.

Clean energy is a subset of renewable energy. But not all renewable energy is clean.

What is clean energy?

Clean electricity takes on two forms. One is electricity produced via fossil fuels, but all greenhouse gases are removed at the power plant. This idea is not as far-fetched as it seems. On the outskirts of Houston, Texas, a prototype natural gas electric power plant is attempting to produce emissions-free electricity using Carbon Capture, Utilization, and Storage (CCUS) technology. Assuming the prototype works, then this technology becomes a viable option for a green, clean future.

Another path towards emissions-free electricity is through generation from clean primary energy. The U.S. Energy Information Administration (EIA) divides renewable energy into five categories: biomass, hydropower, geothermal, wind, and solar. These all represent naturally replenishing energy sources, but this does not necessarily make them clean.

Wood is part of the biomass category, but burning wood releases carbon dioxide (CO2). However, hydro, wind, solar, and geothermal form a subset of renewable energy sources that do classify as “clean.” These sources emit no greenhouse gases. Hydroelectricity traditionally provided the largest source of clean U.S. electricity, but in 2019 wind power surpassed hydro. During the past two decades, wind-generated electricity moved from being a negligible power source to supplying over 40% of the U.S. renewable energy.

Energy Demand and Clean Energy

States have taken the first steps towards a clean energy future, and now the Federal Government is set to join this effort under the Biden Administration. These state and federal commitments are essential. Without them, the financial obligations required to develop clean energy plants become too risky for many investors. A significant portion of the clean energy needed by federal and state governments in fulfilling their goals will come from wind power. Offshore wind-generated power is a significant component of needed clean energy in the U.S., where analysts predict the offshore wind market will be a $70 billion industry by 2030.

Understanding U.S. energy demand shines a light on why clean energy, in the form of offshore wind power, is deemed so necessary. The USA requires 1,100 gigawatts (Gw) of electric power capacity to keep the lights on. Currently, 16% of that energy classifies as clean, and wind accounts for about half the current clean energy generation. Today almost all of that wind power is from onshore production, but this situation will change as we move forward. The U.S. Office of Energy Efficiency & Renewable Energy estimates that offshore wind has a technical capacity of about 2,000 Gw, or almost twice the current electricity demand for the whole country.

Wind has surpassed hydroelectric as the dominant source of clean energy, and its role will continue to grow. But the large-scale provision of wind power is a massive undertaking beyond the reach of many cities. Clean regional power generation will be required for most cities to make significant progress towards eliminating their carbon footprint and running on 100 percent clean energy.


Electricity, a pressure point for mitigating climate change (Source: ArcheanWeb)

Climate Change is a Long Game (Source: ArcheanWeb) or on Medium

States take the lead and move to clean energy (Source: ArcheanWeb)

What Would It Take to Run a City on 100 Percent Clean Energy? By Shannon Osaka; Wired) —

Feature Image: Renewable Versus Clean (Modified by ArcheanWeb) — Original Credit: By Melanie Maecker-Tursun — Melanie Maecker-Tursun,,, CC BY-SA 4.0, Wikimedia commons

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.