Five Renewable Energy Sources

Five Renewable Energy Sources

by Deb Powers

While it may seem to many that "renewable energy" and the quest to harness sources of energy that are less harmful to the environment than burning coal and oil are new, the truth is that most of the renewable energy sources have been around for centuries. Biomass, solar, water and wind were used to power equipment, heat homes and cook food for centuries before we discovered ways to make burning coal and oil more reliable and started depending on coal-fired plants for electricity.

The more you know about renewable energy, the better you'll understand projects that harness renewable energy in your own neighborhood. This is important, because not all projects that are touted as "renewable energy" are necessarily green or good for your community. While I fully believe that we need to move quickly toward using alternative sources of energy, I also fully support examining proposals in your community carefully and understanding the effects that they may have on your life and the environment around you.

The truth is that there are advantages and drawbacks to most anything being proposed. The trick is in weighing the pros and cons and determining which types of projects are best for each area. Here are some quick facts about each of the five best known sources of renewable energy to help you understand projects you may hear about so that you can decide whether you support the effort or not.

Solar Power

Solar power uses heat from the sun and converts it into energy. One of the easiest ways to see how solar energy can be used for heat is with a simple solar oven, a project many kids do in Girl Scouts or Explorers. There are two main types of solar energy plants - photovoltaic and concentrated solar thermal.

Photovoltaic solar power converts solar energy directly into electricity. Solar cells are used to power many small items that most people are familiar with - calculators, watches and landscaping lights. Large solar panel arrays can be mounted on houses or other buildings to provide electricity for residential or business use. These solar panels can provide electricity even in remote areas that are far from transmission lines, but they are also often used on buildings that are connected to the power grid. In those cases, traditional electricity is available to kick in when the sun isn't shining, and if the solar panels produce more power than is used, it can be sold back to the electric company.

Concentrated solar power uses the heat from the sun to warm water or another substance, then uses the steam produced to turn turbines and create electricity. There are currently 16 solar thermal or CSP plants operating in the U.S. that each produce at least 1 MW of electricity. There may be smaller plants as well.

Hydropower

Hydropower uses the energy produced by moving water to create electricity. It is one of the oldest sources of power. Water wheels have been used for centuries to harness energy for mills and other tasks. Hydro power from dams is one of the oldest and most reliable sources of renewable energy.

Hydroelectric power is created when moving water pushes against the blades of turbines, turning a generator. There are two main types of hydroelectric systems - run of the river systems, where the energy of a free flowing river is used, and storage systems, where water is held in a reservoir created by a dam of some sort, then released to turn the turbines.

Biomass

Like both solar and hydro power, biomass is an old form of energy generation wearing a new name. There are many different methods of energy production under the label of "biomass". The best known and understood is burning wood for energy, but it's not necessary to burn fuel in order to create energy. Many of the projects being proposed as "green energy" are biomass projects. They include many waste energy systems, that create energy from the methane gasses created by rotting garbage in landfills. Other systems use human and animal waste to create methane gas which is burned to produce energy. A number of large zoos around the country are testing such waste energy systems.

Biomass energy production also includes crops grown specifically to ferment for fuel, like corn or sugar cane to make ethanol, or using waste vegetable oils or animal fats to make biodiesel fuels.

Geothermal Energy

Geothermal energy uses the heat generated inside the Earth either directly or indirectly to create power or heat. Hot springs and geysers have been used since ancient times to generate heat for homes. Using geothermal energy to generate electricity is a more recent development. The United States currently is the largest producer of geothermal electricity - but it accounts for about one half of one percent of the energy produced in the U.S. California leads the way with 34 geothermal plants, while Nevada has four. Utah, Hawaii and Montana each have one.

Wind Energy

Wind energy is the form of energy that is getting the most publicity these days. Windmills have harnessed the power of the wind for centuries, using it to turn millstones for grinding corn and grain. Modern wind turbines turn generators to produce electricity. A single wind turbine has little impact on the surrounding environment, but many communities are beginning to protest the location of large scale wind farms nearby, complaining of the effects of the noise and vibrations.

Learn More about Renewable Energy

One of the best places to get a balanced view of the pros and cons of each type of renewable energy, including how each is used and what the potential uses may be is at the Energy Kids site developed by the U.S. Energy Information Agency. Written for elementary and intermediate students, the information is accessible and easy to read for anyone.

Photo Credit: Energy Information Administration Energy Kids

The Other Solar Power

The Other Solar Power

by Deb Powers

Solar power brings to mind images of houses topped with solar panels, each house becoming its own little solar plant to transfer the light of the sun into electricity to power all of its appliances and needs. There's another kind of solar energy out there, though, and it looks like a good bet to take up a big chunk of the solar electricity generation market. If you haven't heard about solar thermal power, here's a quick primer and explanation of how it works.

Solar Thermal Power - The Other Solar Energy

Unlike photovoltaic power - solar energy transformed directly into electricity via specially coated panels, solar thermal energy, also called concentrated solar power, uses the sun's energy in a different way. At the world's largest (to date) concentrated solar power plant in Seville, Spain, for instance, giant mirrors focus the hat from the sun on a huge central tower full of water. The water boils, producing steam which turns turbines and generates enough electricity to power up to 10,000 homes.

CSP is being embraced by power companies, who see it as a way to mass produce energy for consumption and keep their hold on the energy market. A number of utility companies across the country and the world are investing in concentrated solar power plants and adding them to their portfolios. One of the more attractive aspects of CSP, though, is that it is scalable. While large, utility-scale concentrated solar plants can supply hundreds of megawatts of energy, smaller CSP installations are quite feasible and can be built on site to supply just the electricity needed locally.

Solar Power When the Sun Doesn't Shine

A recent development makes CSP even more attractive to the large utilities, which are starting to take the lead in solar power development. One of the major holdbacks in the adoption of solar power as a viable mass energy source is its unreliability. After all, when there is no sun shining, there's no energy to transform into electricity. One solution has been to store the electricity in batteries for later use, but the current technology for this is bulky, expensive - and creates the additional problem of battery disposal.

Newer solutions focus on storing the heat from the sun before it is turned into electricity - a much more efficient and economical method. There have been numerous substances tried to store that heat - water, oil, synthetic oil, and the latest - molten salt. Molten salt has demonstrated the capacity to store heat for hours, and release it n a controlled manner that can generate electricity for hours. Current installations can store enough heat to generate electricity for up to six hours after the sun goes down and the U.S. National Renewable Energy Labs are hoping to double that capacity soon. Once that milestone is reached, it will be possible to generate electricity round the clock through solar power.

 Learn More About Concentrated Solar Power (Solar Thermal)

Interested in learning more about solar thermal power? Here's a list of resources where you can read up and find out all that you want or need to know about what may be the most viable form of renewable energy in production.

• U.S Department of Energy: Concentrated Solar Power Basics
• Good/ Blogs: The Other Solar
• National Renewable Energy Labs: Concentrating Solar Power
• Solar Paces: CSP - How it Works

Photo Credit: alla-14 Stock.xchang

Expanding the Grid

Expanding the Grid for Renewable Energy Use

by Deb Powers

Nissan announced earlier this month that their new Nissan Leaf - a true 0-emissions 100% electric car - would make its debut in U.S. showrooms sometime late next year. According to the company, the Leaf is expected to get about 100 miles of everyday-style driving to a full charge. That, they say, fits the way that about 70% of Americans drive. (The actual average is about 67 miles a day. Not typical average, mind you. Average overall.)

One of the reasons that the rollout of the new LEAF is so interesting to me is that Nissan is taking a very logical cross-industry approach in their roll out of their new vehicle. Since June, the company has partnered with five Southwestern cities to prepare for the future by installing high-powered fast charging stations around the city. In short, Nissan is tackling one of the biggest barriers to adoption - the infrastructure to support its electric vehicle - head-on.

It's nice to see someone approaching this in a logical manner. If you've been paying attention in the green blogs section of local and national newspapers, you've probably seen stories about new sources of renewable energy straining the already laboring power grid. In most older industrialized countries, the electric grid is aging and barely managing to keep up with our current levels of power usage. When you add in the strain of having to regulate the varying output of solar and wind systems, the electricity infrastructure is in danger.

The solution appears to be a new Smart Grid system - but that's only one part of preparing for a future where we get out power mainly from renewable energy sources. Nissan's move to get fast charging stations installed in major cities is another part of that effort. Here are some of the most intriguing proposals and ideas - many of them already in prototype or testing stages - for capturing, storing and returning energy from renewable sources to the grid.

Renwable Energy Storage

One of the biggest drawbacks to renewable technologies like solar power and wind turbines is their dependence on weather conditions to generate power. The way to get around that hurdle is to develop "batteries" to store that power so that it can be drawn on and used when the weather conditions aren't right. There are a number of promising technologies to store solar, wind, geothermal and hydro power so that they can be drawn upon during peak hour energy use.

Solar thermal energy storage works by absorbing sunlight and storing the heat from the sunlight in some sort of substance that retains it for a long time. One of the most commonly used substances is molten salt, but there are others as well. One of the most promising for the average household using solar energy is one being developed at MIT using water and photosynthesis for solar energy storage.

Two different projects at opposite sides of the US are working on converting one of our largest existing infrastructure elements into solar energy collectors and storage. In Idaho, Solar Roadways is building roads that will collect solar power and use it to power charging stations, as well as providing power for nearby businesses and homes. And at Worcester Polytechnic Institute (WPI), a research group is working on ways to generate both heat and electricity from asphalt parking lots.

One of my favorite projects, though, considers adding a solar storage battery to one of our most common items - the household car. If this works out, you could conceivably drive to work, park your car in a sunny spot all day, and then when you get home, plug it in to  your household circuit to draw on that energy to power your lights, computer and other electrical gadgets.

Charging Stations

One of the barriers to all-electric vehicles is the shortage of places to charge up your battery - along with the amount of time it takes to charge up. The LEAF, for instance, takes 16-18 hours to fully charge using 120V household power. If you use 240V power on a dedicated circuit - like your electric dryer uses - that time is cut to about 6 hours. With a high-powered fast charge station, you can fully charge the battery in under half an hour. Of course, few people are willing to sit at a charging station for half an hour waiting for their vehicle to recharge - which has led to a number of ideas for placing charging stations where people will use them. For instance:

McDonalds is already adding electric vehicle charging stations to two of its newest branches. Pull in, park and plug so your car can recharge while your kids eat their happy meals. Couple this with another renewable energy technology being tested at a couple of high-traffic Mickey D's - capturing kinetic energy to be used for electricity generation - and your local fast-food place could become a food-and-fuel island.

Whole Foods, which already sets aside some of its parking spots specifically for hybrid cars, is planning to experiment with providing some parking spots with charging stations for electric cars.

Imagine the possibilities. Think about the places where you park your car for extended periods of time.

• Parking garages that offer Park 'n' Charge services, possibly with attendants who will charge your car, then move it to a parking spot when it's fully charged. 
• Restaurants with valey parking and charging service
• Strip malls with charging stations and video arcades so that you can amuse yourself while your car gets a top-up
• Supermarkets and department store parking lots

Even better, Nissan's latest partnership is with Showa Shell to build recharging stations powered totally by solar panels. If those work out and catch on, we could be looking at true zero-emission electric cars.