DEEP: xxxRenewable Energy

Renewable Energy
The term renewable energy generally refers to electricity supplied from renewable energy sources such as wind and solar power, geothermal, hydropower, and various forms of biomass. These energy sources are considered renewable sources because they are continuously replenished on Earth.
Why Renewable Energy?
Renewable Energy is a clean source of energy that can replenish itself for thousands of years to come. Fossil fuels on the other hand are finite, create harmful greenhouse gases and other emissions, and can require dependency on countries outside of the United States. Renewable Energy is important to lower our carbon footprint, lessen our dependency, and also helps to create jobs within the U.S.
For more information on renewable energy technologies, please visit Energy Basics: Renewable Energy on Energize Connecticut.
Renewable Portfolio Standard (RPS)
A renewable portfolio standard (RPS) is a state policy that requires electricity providers to obtain a minimum percentage of their power from renewable energy resources by a certain date.
The Connecticut Green Bank offers incentives and innovative low-cost financing to encourage homeowners, companies, municipalities, and other institutions to support both renewable energy and energy efficiency.
Types of Renewable Energy:

Solar Power
{Solar panels - Photo Courtesy of DOE/NREL} The sun is the most powerful energy source that we have access to and is the source of the majority of the renewable energy that we currently use.

Passive solar heating has been the primary usage of solar energy as it is simply letting the sun shine on the places that we wanted to heat, whether it is a home, a business, or even pools and water. This type of heating can be made more efficient through architectural design and construction techniques that make the best use of the sun’s rays throughout the day; less sun in the summer when it is not needed and more sun in the winter when heating is needed.

Active solar energy is becoming more and more common as people install more solar panels on their homes, business, or in parking lots. There are two types of solar panels that we currently use, photovoltaic (PV) and solar thermal, and they both work by capturing the sun’s rays and converting them into usable energy. Solar PV is different from solar thermal in that solar PV converts the sun’s energy directly into electricity while solar thermal uses the sun’s energy to heat water (or food-grade antifreeze in the colder climates) to produce heat for a home or steam to run a generator for electricity.
Wind Power

{Grasso Technical High School turbine} Harnessing the power of the wind is smart, clean, and relatively cheap. Europeans have been using wind power for centuries and in the United States, farmers have used small windmills for many years to pump water for irrigation and drinking or to grind grain.

The science is simple: all you need is wind, which, granted, is not in abundance everywhere. That’s why engineers have created enormous propeller-like blades – some a hundred yards long – that can capture even the slightest breeze. Wind farms utilize hundreds of these aerodynamically advanced wind turbines – comprising of composite materials and sophisticated electronics – to rotate the blades and turn generators, producing bulk electrical power. Large wind farms tend to be built in the plains, on hills, on mountains, and some states are in the process of installing them offshore. The electricity that the wind turbines produce is typically fed into the local utility grid for public and private consumption.

Smaller versions of these large rotors are available for residential use; a small home-sized wind turbine has rotors between 8 and 25 feet in diameter and rises 30 or more feet. It can supply the power needs of an all-electric home or small business, and can be either grid connected or connected to batteries that store excess electricity for the days when the wind does not blow.

The newest version of wind turbines, the vertical axis wind turbine (VAWT), differs from the more traditional horizontal axis wind turbine (HAWT) in that, instead of the long propeller blades, the VAWT uses a long vertical tower with blades in an eggbeater, H, V, or delta (D) shape. These designs allows for the turbine to capture wind without having to turn the blades so that they are parallel to the direction of the wind as a traditional HAWT model would have to do. While VAWTs may be more efficient at capturing wind, it is currently still too cost-inefficient for land-based large-scale or utility-scale usage.

One of the drawbacks of wind is that it takes a large amount of wind turbines to generate enough electricity to meet our needs. Some people feel that these massive wind farms are scars on our earth. In our region, offshore wind farm proposals have been met with great opposition and the commercial and residential marine traffic, along with the lower wind speeds in Long Island Sound, limits Connecticut’s potential for offshore wind.

For more information, visit Energy Basics: Wind on Energize Connecticut.

Geothermal Power
{Geothermal wellhead - Photo Courtesy of DOE/NREL} Geo-exchange technology has been utilized since the late 1940s as a method to generate efficient, renewable, and clean energy from the natural heat inside the earth. While many parts of the country experience broad seasonal temperature extremes – from scorching heat in the summer to frigid cold in the winter – the temperature a few feet below the earth’s surface remains relatively constant. This ground temperature is warmer than the air above during the winter and cooler in the summer.

Geothermal heat pumps (like the one pictured above) take advantage of the temperature difference by exchanging heat with the earth and are able to heat, cool, and even provide hot water if they are properly equipped. These heat pumps use fans and compressors and are quieter than air-source heat pumps, though many systems combine air-source and geothermal-source pumps for added efficiency.

Geothermal systems are more expensive than standard air-source systems, but the additional costs can be realized in savings over approximately ten years. The ten-year payback period might seem long but these systems generally have a 25-50 year warranty.

To learn more, visit Energy Basics: Geothermal on Energize Connecticut.

Hydropower {CT River- Photo Courtesy of CT Commision on Culture & Tourism}

Hydroelectric generation was once a staple wherever there was a river or a fast-moving stream. Even today, enormous dams are being built across the world that rival the wonders of great U.S. civil engineering feats like The Grand Coulee and Hoover dams. On the Columbia River Basin in the Pacific Northwest alone, there are several major hydro-electric-producing dams generating more than 40% of the total U.S. hydroelectric power. A well-known example of a powerful hydroelectric station is the Niagara Falls Power Station, which produces some of the cheapest electricity in the world.

In addition to the large-scale hydropower around the U.S., Connecticut has many small public and privately owned hydroelectric facilities that produce clean, renewable energy for the regional power grid.

When it comes to producing electricity from water, the bigger the drop, the more energy it will produce. That is why there are few hydro facilities in Kansas. The concept of hydropower is simple: water drops down or over propeller-like blades connected to a turbine, which is connected to a generator by a metal shaft. When everything moves, electricity is generated, redirected, or stored for future use.

Other water-based sources of power include wave and tidal power, as well as ocean thermal power. Wave power technologies extract power from surface waves or from water fluctuations below the surface. Tidal power relies on tidal currents to spin the turnstiles or turbines to generate electricity. Ocean Thermal Power uses the difference in temperature between the warm top layer of the ocean and the colder, deeper water to generate electricity. Unfortunately, Ocean Thermal Power is only possible in limited areas of the world, such as the Tropic of Capricorn and the Tropic of Cancer, and has high upfront costs.

Visit Energize Connecticut's Energy 101 section to learn more about Hydropower and Ocean Power.

Biomass Power
{Biomass - Photo Courtesy of DOE/NREL} Creating energy from biomass – the generic term used for organic material that comes from food crops, wood, oil-rich algae, and organic components of garbage that can be burned or broken down to create steam, heat, and/or electricity – has gained popularity as an alternative to fossil fuels.

Burning wood has been a heating and cooking staple since the dawn of humanity. Depending on where you live, it is still relatively easy to gather, although it is time consuming and bulky. In addition, the wood need to be stored and cured for maximum efficiency, though aged wood can be easily purchased and delivered to your home. Modern stoves are also far more efficient than stoves of the past, and wood can be purchased in small, concentrated pellets, making handling and storage much easier.

Many manufactures and utility companies burn waste products – everything from garbage and wood byproducts to waste oil and even sewage sludge – for energy and heat but this needs to be carefully monitored to ensure that dangerous pollutants are not released into the atmosphere or allowed to contaminate water sources. The excess energy that is produced through these alternative energy sources is often sold back to the electricity companies and added to the regional power grid and as additional motivation, the state has stepped in to offer tax incentives and grants for these projects.

Biomass can also be used to create biofuels such as ethanol and biodiesel. Biofuels, biogas, and the burning of biomass in general offers a cleaner alternative to the comparative fossil fuel as burning fossil fuels releases carbon captured millions of years ago while biomass releases carbon captured recently. Done correctly, biomass is both sustainable and renewable and is a net-zero emitter of carbon dioxide. One specific bio-power technology is Anaerobic Digestion, which uses microorganisms to breaks down biodegradable materials in the absence of oxygen to create biogas. The biogas is then used as fuel for electricity and heat production and can be used in a Combined Heat and Power unit to produce both heat and power.

More information on Biomass can be found on the DEEP's Biomass page or visit Energy Basics: Biomass on Energize Connecticut. More information on Anaerobic Digestion can be found at Energy Basics: Anaerobic Digestion.

Fuel Cells

{Bridgeport Fuel Cell}

Connecticut is a world leader in hydrogen fuel cell technology and research. Fuel Cell in Bridgeport, CT has 14.9 megawatt capacity and powers thousands of nearby homes.  Hydrogen fuel cells are composed of stacks of individual cells that collectively form a unit. These units contain a cathode and an anode that form a sandwich around a catalyst. Hydrogen enters the cell through the anode and is split into electrons and protons by the catalyst. The electrons are funneled out to power the system while the proton passes through the catalyst. Both entities rejoin at the cathode which introduces oxygen, creating H20 as a byproduct along with heat. This in turn allows hydrogen fuel cells to be incredibly efficient and environmentally friendly as the only byproducts are water and heat.

Hydrogen fuel cells come in a variety of configurations giving them a diverse array of uses. Powering automotive vehicles and buildings are some of the main uses for this technology. However, fuel cells are also used in handheld devices, commercial power plants, military applications, and space exploration. Along with being used as a primary source of energy, hydrogen is an excellent energy storage option. Unused electricity can be diverted to convert water into hydrogen, which can be used in fuel cells later.

Some key advantage of fuel cells are there diverse sizes and configurations allowing them to be used anywhere. They produce energy as long as fuel is present which eliminates the intermittency associated with many renewable energy sources. The largest limitations to fuel cells is the lack of infrastructure and services associated with them. This is due to fuel cells being new and expensive technology however, their use is catching on.


Content Last Updated October 2017