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Renewable Energy > RE General Discussion > Renewable/Alternative Energy, Where to Start
People often talk about using alternative energy in their homes or businesses, but do they understand what those alternatives are? I have built many of my own alternative energy systems and have thought that I had captured a new alternative energy, only to find out that what I had indeed done was used a form of energy that has always been available to folks for many years. Renewable energy and alternative energy are often used interchangeably since most people do not view traditional energy sources as alternative energy sources. I have written this article to provide some insights into what is “Alternative Energy” and how do we use it?
First Things First
When people think about using alternative energy sources, they often don’t think of the obvious areas to capture energy. Here are some suggestions for capturing energy that is often wasted in homes and businesses:
1. Insulation – Unless they are LEED certified, most homes and businesses are either losing a lot of heat energy in the winter months or using a lot of cooling energy in the summer months due to inadequate insulation. The first area one should look at in thinking about alternative energy is how well insulated their building is. Insulation in homes and buildings is usually measured in R-Value, which is the resistance to heat flow through a particular substance. The higher the R-Value, the greater is the effectiveness of the insulation. Typically a home built with 2”X4” outside walls filled with fiberglass insulation will have an R-Value range of between 10 and about 13 depending on what other materials are used for the outside walls and how well the building was constructed. Along with insulation, we must also take a look at the ventilation of those areas such as attics, above ceiling spaces etc. A well-insulated building with adequate insulation and ventilation can go a long way in reducing energy costs.
2. Caulking – Sealing up air leaks in a building can also significantly reduce the loss of heat in the winter and the infiltration of heat during the summer. Many times we neglect to check our door thresholds to make certain that there is no air leaks or perhaps a neglected window that needs repaired. Checking around the outside of your building for possible air leaks and sealing them up is not only a cost effective way of reducing your energy use, but it also helps keep out pesky critters.
3. Energy efficient appliances – More manufacturers are building not only more efficient appliances and machines, but they are also building smarter appliances and business machines. We need to be looking at how much energy our older business machines and appliances are using and decide whether newer equipment might provide a high enough savings to pay for the replacement within a few years. There are a number of energy gadgets out there that can help us calculate what those savings might be. As more people begin to look at their energy use, they have available to them very inexpensive gadgets such as the Kill A Watt, or the Kill A Watt EZ Meter and for those who want more accuracy and can afford it, the HOBO Plug Load Data Logger. Once you have identified how much energy different appliances within your building are using, you can compare their energy use to what a new appliance uses and how long it would take you to reach a pay-back on that appliance. Some newer appliances are smart enough to power down when not in use and power back up when they are needed. Some appliances may even be able to calculate how much energy they are using and provide that information to your personal computer.
4. Energy efficient lighting – We have come a long way in creating better lighting with less energy. Incandescent light bulbs can not only generate a lot of light but also generate excessive heat. We have seen the move from incandescent light bulbs to CFL and now to LED lights. The manufacturers of LED lights have just recently been able to master the art of providing the right amount of light intensity coupled with the right amount of light temperature. When purchasing LED lights it is important to remember that the light intensity is measured in lumens and the light temperature is measured in degrees kelvin. An LED light that has the lumen capacity and the temperature capacity of a typical 100 watt incandescent light bulb, should be rated at about 1600 lumens and have a temperature rating between 2700 and 3000 degrees Kelvin.
Geothermal Energy
Unless you happen to live in an area where hot springs are abundant, you probably will not be generating electricity using geothermal energy. There are however ways of harnessing geothermal energy and using it to heat your home or business at a much lower cost than using conventional electric, gas, coal, or oil heating systems.
Heat pumps in the form of air conditioners have been around for decades. In recent years the technology used for air conditioners has developed to the point where reversible heat pumps can economically heat homes and businesses by converting the existing heat from outside air to a more concentrated form of heat to heat a home or business. Heat pumps do use electricity to generate their heat although they operate much more efficiently than electric resistance type heat sources. One of the problems with heat pumps is that they work more efficiently when the ambient outside air is above 32 degrees Fahrenheit.
Since ground water is usually warmer than outside air temperatures during the winter months in North America, ground water or geothermal heat pumps can produce heat much more efficiently than air heat pumps. Geothermal heat pumps are becoming more common and have improved both in efficiency and in reliability.
Solar Energy
Generally speaking there are two types of solar energy collection systems; Thermal Solar and Solar Electric or Photo-voltaic. Solar thermal systems can be divided into active and passive systems and within those categories they can be further broken down by the media with which the thermal heat is transferred, for example solid, liquid, air or perhaps even electric. Photovoltaic (PV) systems generate electricity through a process called the photoelectric effect, where materials such as silicon, a semiconductor, absorb light photons and release electrons. The free electrons are captured to provide an electric current.
Site Evaluation – After you have taken care of any energy wasting items within your building, the next thing you need to think about when looking to harnessing the sun’s energy, is how much solar radiation you can expect to occur for the specific site where you want to install some type of solar collection device. Where does the sun rise and set in the summer and where does it rise and set in the winter? What obstacles may impede the solar radiation, such as other buildings, structures, trees, hills and or mountains? What is the average solar radiation one can expect for a particular latitude and location with respect to the average weather conditions such as clouds and precipitation? All of this information is gathered into a report known as a site evaluation. Armed with a good site evaluation, you can now proceed to the next step of identifying what type of energy collection device would be most appropriate based on needs and the amount of funding available to fill those needs.
Active Solar Thermal heating systems – An active solar air heater can be as simple as a five-sided insulated box painted black on the inside with thermal glass covering the side facing the sun and a fan or blower pulling the resultant hot air into a room. An active solar air heating system may also have reflectors that move with the sun to reflect additional heat energy onto a collector that may use fans or blowers to move the heated air into thermal heat sinks where the heat can later be used when the sun is no longer shining. An active solar thermal system may pump liquids through glass enclosed tubes which are exposed to the sun’s rays. The heated liquid can then be stored or used to either heat water or the air in a building. Reflectors can also be used to concentrate sunlight onto a boiler where superheated water turns to steam and is used to generate electricity. Other active solar thermal systems have the capability of running sterling engines by using the temperature difference between a heated liquid or gas and the ambient temperature within the environment. The sterling engine can then be used to run an electric generator.
Passive Solar Thermal systems – If you have ever walked into a sunroom or garden room when the sun was shining, you no doubt felt the passive effects of the sun as it heated that space. There are various ways to collect and mediate the temperature in a space where the sun’s warmth is felt. One type of passive heating of a space is with a “Trombe Wall”. A Trombe wall is a wall that has a glass exterior facing the sun and a heat absorbing material on the inside separated from the glass by a thin layer of air. The sun’s rays pass through the glass windows or walls and are absorbed by the wall. The Trombe wall then releases that heat energy into the air at night. Usually a Trombe wall is made of a very dense material such as stone, concrete or even tanks of water. Most Trombe walls are built with an outside eve that can shade the wall from the summer sun and thus keep from overheating during the summer months.
Heat sinks of concrete, stone, water or brick can also be incorporated into rooms that are exposed to the sun’s heat energy. In some cases, this could be called a modified Trombe wall where the entire room structure is used as a Trombe wall heating system. The heat sinks tend to absorb the sun’s heat during the day and release it during the night. One type of passive solar heating system for water is a water tank painted flat black and encased in an insulated enclosure that is exposed to the sun. As the water slowly flows through the tank, it absorbs the heat energy from the sun and provides for a way to preheat the water before it goes to other active heating systems. Arizona rooms, Florida rooms, or whatever you want to call your sun room can be used to provide passive heat to an adjoining room while also providing a space to grow beneficial plants.
Photovoltaic electric systems – Photovoltaic or PV panels have recently become much more efficient than in previous years. Not only have PV panels become more efficient, but the cost of installing PV systems has come down to the point where it is more economically feasible to consider having a PV system installed. The electrical energy produced from PV panels can be stored in batteries or fed into the electrical grid to offset the amount of electric power being used from the grid. PV panels generate DC current so they must either be combined with a whole house inverter or the appliances and lights within the house must be capable of using DC current. A whole house inverter converts a solar-electric array’s DC electricity into AC current for the entire building to use. Some of the new PV panels being developed have micro-inverters attached to them which convert the DC current from the photoelectric cells into a standard 110-120 volt AC current which can be tied into the electric panel of a home using standard wiring.
Photovoltaic panels can be broken out into three basic types: Monocrystalline, Polycrystalline, and thin film or amorphous. The difference in these three types of PV panels is their structure and the efficiency at which they are able to generate electricity. Monocrystalline panels which are manufactured from a slice of a single silicon crystal and operate at between 18% to 21.5% efficiency, however their cost is usually higher. Polycrystalline panels are built using cells sliced from a block of silicon and will operate at between 14% to 17% efficiency and their cost is generally lower than that of monocrystalline panels. Finally, Thin-film or amorphous panels usually operate at between 12% and 14.5% efficiency and their cost is the lowest of the three types. One other consideration concerning the three types of panels is the amount of space that the panels require for installation. The higher the efficiency of the panel of cells, the less space is required for their installation. In some cases the same size polycrystalline panels may be more efficient than monocrystalline panels simply because the monocrystalline cells are round and thus require more space on a panel than the rectangular polycrystalline cells.
Wind Energy
One of the fastest growing alternative energy areas today is in the large scale wind turbine industry systems. Although large scale wind turbines can each generate more than 2 Megawatts of electricity, the cost of installing and maintaining small scale wind turbines for small businesses and home owners is much higher than that of small scale solar electric systems.
Most wind turbines especially large scale operations are constructed as horizontal axis wind turbines or HAWTs. Large scale HAWTs require a fairly large air space area to operate efficiently. Some environmentalists have concerns about the safety of large HAWTs since the end of the blades can be traveling at very high speeds. There can be a problem with birds being struck by the blades and there also can be a problem with ice buildup in colder climates where the ice can be flung into the air and possibly damage property or worse yet injure someone standing nearby.
One solution to the dangers of the HAWT is to build a vertical axis wind turbine, or VAWT. VAWTs require less space for their operation and have a much lower bird strike probability since their vertically rotating blades take up less air space and can more easily be seen by bird populations. The tighter air space of a VAWT also tends to minimize ice buildup and is therefore less likely to cause property damage or injure bystanders. Because of the safety issues, VAWTs are becoming more common in urban environments.
There are other alternative renewable energy sources such as water or hydroelectric power and less common sources such as wave power systems. Solar and wind power have the potential to replace other large scale electrical power sources such as fossil fuels without producing as much pollution with the added ability to use existing spaces such as rooftops and farm fields with minor impacts.
As the solar industry continues to produce more efficient solar cells we will have the ability to use more and more of the sun’s abundant energy to provide power to our homes and to our industrial base.
Ed Kirkpatrick
