By the United States Department of Energy. Glossary of energy-related terms:
Renewable Energy
Energy derived from resources that are regenerative or for all practical purposes can not be depleted. Types of renewable energy resources include moving water (hydro, tidal and wave power), thermal gradients in ocean water, biomass, geothermal energy, solar energy, and wind energy. Municipal solid waste (MSW) is also considered to be a renewable energy resource.
Solar power:
The majority of renewable energy technologies are directly or indirectly powered by the Sun. Solar energy can be captured by solar panels. There are 2 main types of solar panels which uses complete different technologies to make use of the energy from the sun:
- Solar Water Heating collectors: These panels absorbs the energy from the sun and transfer it to heat water.
- Photovoltaic or solar electric panels: These panels transform the solar radiation directly into electricity.
For maximum efficiency, solar panels should be mounted on a south facing roof at a 30° angle with the horizontal and away from any shadows from trees, surrounding buildings or chimneys.
Solar water heating
Solar Power Solar water heating systems are the most popular form of solar energy used. The system is connected to the hot water system. Solar water heating systems can provide over half of a household’s hot water requirements over the year. Solar water heating panels in their simplest form are made from a sheet of metal painted black which absorbs the suns energy. Water is fed through the panel in pipes attached to the metal sheet and picks up the heat in the metal. For the UK climate the pipe work contains non-toxic anti-freeze. The pipes are often made of copper for better conduction. The metal sheet is embedded in an insulated box and covered with glass or clear plastic on the front. The system is usually installed on the roof. The evacuated tube system is a series of glass heat tubes grouped together. The tubes are highly insulated, due to a vacuum inside the glass.
Photovoltaic (Solar Electric)
Photovoltaic (PV) or solar electric can offer us all the ability to generate electricity in a clean, quiet and renewable way. The variety of applications for solar electric are numerous. Photovoltaic (PV) cells are used in simple applications e.g. calculators and watches and also for domestic and larger applications. Large PV systems can be integrated into buildings to generate electricity for export to the National grid. PV applications today are more common place than we might expect. Domestic burglar alarm systems are now fitted with PV panels to charge the battery for the system. In Milton Keynes, parking meters are powered by solar panels. Many leisure activities are today turning to PV panels for back up electricity, including TV, lighting in caravans and nautical instrument.
The daylight needed is free, but the cost of equipment can take many years before receiving any payback. However, in remote areas where grid connection is expensive, PV can be the most cost effective power source.
Passive solar
The use of passive solar design is possibly the simplest form of solar energy. Many buildings today are designed to utilise the energy of the sun as efficiently as possible. The location and orientation of the building are all key factors in optimising passive solar design. Passive solar design can be best applied in new buildings, where the orientation of the building, the size and position of the glazed areas, the density of buildings within an area, and materials used for the remainder of the structure are designed to maximise free solar gains. Designing a property to maximise free solar gain need not add to the price of construction.
Studies on houses in Milton Keynes have shown that low cost passive solar design features and draughtproofing and insulating measures reduced heating bills by 40%. Savings paid back the costs in two years.
Wind power:
The wind blows the propeller round, which turns a generator to produce electricity. The tendency is to build many of these towers together, to make a “wind farm” and produce more electricity. The more towers, the more wind, and the larger the propellers, the more electricity we can make. It’s only worth building wind farms in places that have strong, steady winds, although boats and caravans increasingly have small wind generators to help keep their batteries charged. The best places for wind farms are in coastal areas, at the tops of rounded hills, open plains and gaps in mountains - places where the wind is strong and reliable.
Water power:
Large scale hydroelectric power has been used worldwide for a long time to generate huge amounts of power from water stored behind massive dams. Small scale hydropower has been used for hundreds of years for manufacturing, including milling grain, sawing logs and manufacturing cloth. However, it can also be used without a dam to generate electricity for home scale remote power systems. These so-called micro-hydro installations can be a very good complement to a solar power system, as they produce electricity 24 hours a day.
Waterwheels-It’s important to differentiate between water wheels and water turbines. A water wheel is more akin the antique version we are all familiar with a massive wooden wheel that slowly turns as the creek pours down over it. Water wheels spin slowly, but with lots of torque. They are also surprisingly efficient!
Biofuel:
Biofuels include ethanol and biodiesel derived from organic matter such as sugar cane, vegetable or corn oils. Not all ethanol is suitable to be used as a motor fuel blend.
The International Energy Agency (IEA) predicts ethanol alone has the potential to make up 10 percent of world gasoline use by 2025 and 30 percent in 2050, up from around 2 percent.
Considering the fuel costs involved in farming, is not the concept of biofuels somewhat contradictory? Yes, the final product may have chemically derived from a plant based origin, but how much fossil fuel is consumed in the process of creating each gallon of biofuel?
For this reason, programs that recycle/convert already existing pre-cursors into fuel seem the most plausible, such as griesel or biomass.
Solid biomass:
Biomass, sometimes known as biomatter can be used to produce biofuel. This fuel can be delivered in many forms, such as biodiesel to fuel modern diesel vehicles and heat to heat water and drive turbines. Biomass comes in many forms, such as waste and crude vegetable and animal oil and fats (lipids), sugar cane residue, wheat chaff, corn cobs and other plant matter. In fact biomass can be defined as any recently living organisms or their metabolic by-products, such as manure from cows.
Though often considered as a member of the solid biomass family, dried compressed peat is not strictly one. It does not meet the criteria of being a renewable form of energy, or of the carbon being recently absorbed from atmospheric carbon dioxide by growing plants. It is regarded as a fossil fuel and when burned it adds to the CO2 present in the atmosphere.
Plants partly use photosynthesis to store solar energy, water and CO2 and this matter can be, and is, burnt quite successfully. An advantage of this process is that no net CO2 is released, whereas animal faeces release methane under the influence of anaerobic bacteria. These methods can all be used to generate electricity. Of course electricity is not the only form of energy available by utilizing solid biomass. In some areas corn, sugar beets, cane and grasses are grown specifically to produce biomass fuels, such as biodiesel, ethanol and bagasse (often a by-product of sugar cane cultivation) that can be burned in internal combustion engines or boilers.
Typically biomass is burned to release its stored chemical energy. Research into more efficient methods of converting solid biomass and other fuels into electricity utilizing fuel cells is an area which is ongoing.
Geothermal energy:
Geothermal energy is the heat energy that occurs naturally in the earth. The energy is recovered from the heat of the earth’s core. In nature, geothermal heat shows up in the form of volcanoes, hot springs and geysers. The heat itself is derived from radioactive decay beneath the earth’s surface. In certain locations, it is concentrated and is close enough to surface waters to be brought to the surface for many different purposes. When it is above 150 degree Celsius, it is considered hot enough to be used to generate electricity and heat.
For thousands of years, humans have used naturally occurring hot springs for bathing. More recently, geothermal energy has been used to generate electricity, and to provide heat for homes and industries. Geothermal energy is a versatile and reliable source of heat and electricity which generally produces none of the greenhouse gases associated with the combustion of fossil fuels. Unfortunately, the best geothermal resources are concentrated in areas of volcanic activity and are not widely distributed. California, Iceland, Italy, New Zealand and Japan are all areas where geothermal energy is used on a significant scale.
Renewable energy, combined with the smart use of energy, can deliver half of the world’s energy needs by 2050 contributing clearly to a new and cleaner World.
http://www.eere.energy.gov/consumer/information_resources/index.cfm/mytopic=60001
http://www.greenenergy.org.uk/pvuk2/
http://www.re-energy.ca/
http://www.energy.iastate.edu/renewable/solar/
http://www.cnn.com/TECH/science/9901/05/windpower.enn/
http://www.scienceclarified.com/Al-As/Alternative-Energy-Sources.html
http://appsci.queensu.ca/ilc/sustainability/energy/water.php
http://www.biofuel.it/en/
http://www.esru.strath.ac.uk/EandE/Web_sites/03-04/biomass//background%20info2.html
http://www.gcse.com/energy/geothermal.htm
http://www.enn.com/today.html?id=12095
jmgs
pgomes
filipefernandes