8/8/2019 Alternative Energy Basics

1/2

Alternative Energy BasicsBY ANNA BOGDANOWICZ With alternative energyparticularly wind, solar, and biofuelso much in the news lately, a littletutorial might be useful. Harvey N. Weintrob presented just that during the IEEE InternationalTelecommunications Energy Conference in June, in Orlando, Fla. The conference was sponsored bythe IEEE Power Electronics Society. Weintrob is an instructor at Dan McMenamin and Associates, a

consulting and training services company in West Deptford, N.J., that specializes intelecommunications and power equipment design, including alternative energy systems.

WIND POWERA wind turbine converts the winds kinetic energy into electricity, with the turbines blades spinning ona shaft that connects to a generator. The most common type of turbine has a horizontal axis, andblades that resemble airplane propellers.

Wind turbines are often grouped together at a power plant, or wind farm, or a green-oriented citizenmight install a wind turbine at home. Electricity from the turbines is fed to the grid.

Wind farms are popping up around the world, with Denmark leading the way. About 20 percent of thecountrys energy is now produced that way. Wind power generates 11 percent of Portugals electricity,

about 10 percent of Germanys, and roughly 5 percent of Indias.

The windiest U.S. locations are found in California, Colorado, Idaho, Kansas, Maine, Montana, andNew York.

Whether a wind turbine at your home or business is a sound energy choice depends on the statementoften made about real estate: Its all about location, location, location, Weintrob says. Areas with anaverage annual wind speed of at least 20 kilometers per hour are considered good for turbines.

Although the turbines have relatively little impact on the environment compared with fossil fuels,drawbacks include noise from the blades, complaints of unsightliness, and concern over birds andbats killed by flying into them.

SOLAR ENERGY

Solar systems rely on cells that convert light into electricity. The photovoltaic cells are made ofsemiconductor materialsoften some variety of siliconthat absorb sunlight and produce an electriccurrent.

A typical photovoltaic system is composed of solar panels made of rows of individual cells, a batteryto store the energy, and a charge controller that monitors the battery and ensures it isnt overcharged.Most solar-energy systems, which generate direct current, also require a DC to AC inverter to switchfrom the battery-stored DC to standard AC power.

How much electricity the cells generate depends on how much of the suns energy reaches the cells.Typically, solar panels are mounted on a roof and oriented to face south to get the most rays. But theycan face up to 45 degrees east or west without significantly decreasing output.

Germany is the top producer of solar energy, with China, Japan, and the United States among theleaders.

The disadvantages of photovoltaic systems are their high purchase price and installation cost, andthey generate peak electricity only during sunny days. The cost of installation varies depending on thesize of the system, ranging from about US $16 000 for a modest home to $100 000 for a large one.

More information on solar energy systems is available at the National Renewable Energy LaboratorysPVWatts Web page, which includes links to calculators to help you determine the cost savings ofusing solar cells instead of electricity from the grid.

8/8/2019 Alternative Energy Basics

2/2

BIOENERGYBiofuel is derived from biomass, which is organic material from such things as plants and manure.Ethanol made, for example, from sugar cane in Brazil or corn in the United States, is the mostcommon biofuel. It is produced by fermenting sugars derived from the sugar cane or corn, as well asfrom wheat or molasses. Ethanol derived from the process is used as a somewhat lower-poweredreplacement for gasoline.

Biodiesel, another type of biofuel, typically is made from soybean oil. Biodiesel in its pure form can beused as a fuel for vehicles, but it is usually mixed in as a diesel additive to reduce levels ofparticulates, carbon monoxide, and hydrocarbons emitted by diesel-powered vehicles.

Although biofuelsas other alternative energy sourcesare not carbon-neutral, because energy isrequired to grow crops and convert them into fuel, there are advantages. Bioenergy can be producedusing organic waste that might otherwise be discarded, thus reducing the environmental andeconomic cost of disposing of them.

Countries where bio-energy systems have been expanding include Germany, Italy, and the UnitedKingdom.

When youre deciding on an alternative energy system for your use, make sure to look into state andfederal tax incentives. Many governments offer credits or rebates for installing alternative systems.