March 11, 2008

Energy-Off Grid

What is off grid?
Off grid technologies allow for private homes and people to access
Environmentally friendly methods of attaining power independently from public power sources.

The benefit of off grid power is that it can decrease or rid customers of a power bill, allowing the consumer to make more environmentally conscious decisions about the source of their power (if local power companies are not already doing so).
Some states, such as California give large rebates and cash back to private individuals that utilize off grid technology. If you connect home-generated power to the grid, you can add power back to the grid, running your meter backwards, potentially making a bit of money (though this is usually minimal).

What are the Options?

Due to the price of solar power systems, solar power is most common in off grid applications. There are two types solar energy systems: solar thermal systems collect radiant energy to produce heat; photovoltaic-cell systems convert direct sunlight into a stream of electrons to produce energy.

Photovoltaics are the most common form of off grid home generated power. Many homeowners are proud to have solar panels bolted to their roofs, but those who want solar power without the bolt on look can now use building integrated photovoltaics. Most of these are solar shingles, which are intended to cover your roof like shingles. Most of these shingles tend to be between 10-20 percent efficient. Though photovoltaics have been around since the 1970’s, new materials have allowed them to be produced in a myriad of ways allowing them to be used in a variety of ways from building materials, to components on new gadgets. Also, the modular setup of solar power means it is easy to expand on existing solar projects.

Wind is generally considered the cleanest alternative energy source, and is beginning to scale down for home use (though it tends to be more practical in rural environments than urban ones). A small wind turbine is enough to offset a good portion of electricity in a typical home, and best of all can be easily retrofitted to existing homes.

Anew breed of vertical axis wind turbine (VAWT) from Helix Wind offers a promising design that may change the way we do wind at home. The Helix Wind Savonious 2.0 uses a unique rotor capable of capturing omni-directional winds to provide quieter, kinder small wind power for your urban home.

Have a small stream or creek on your property? Waterwheels have been used around the world for centuries to mill grain and de-hull rice. Now some of these wheels are being retrofitted with generators to provide electricity, too. In some places, entirely new systems are being installed, these systems are called micro-hydro systems, because they are generally capable of powering only a few houses or a small village and they can be plopped down in a river without significantly affecting its flow, banks or general ecosystem as a large hydroelectric dam would.

Ground-source heat pumps use the earth or groundwater as a heat source in winter and a heat sink in summer. Using resource temperatures of 4°C (40°F) to 38°C (100°F), the heat pump, a device which moves heat from one place to another, transfers heat from the soil to the house in winter and from the house to the soil in summer.
Geothermal heat pumps can be used almost worldwide. The earth's temperature a few feet below the ground surface is relatively constant everywhere in the world, while the air temperature can change from summer to winter extremes. Unlike other kinds of geothermal heat, shallow ground temperatures are not dependent upon tectonic plate activity or other unique geologic processes. Thus geothermal heat pumps can be used to help heat and cool homes anywhere.

Fuel Cell
Fuel cell technology can be used to make electricity to power vehicles, homes, and businesses. Unlike conventional technologies, fuel is not burned but is combined in a chemical process. A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water, and heat.

The problem with fuel cells is that the hydrogen utilized to power the cells must be initially produced by a primary energy source. The idea is, if you use a renewable energy source as the main source of hydrogen, a fuel cell can be considered a renewable energy source. It is more efficient to just use the renewable energy source from the start though, making hydrogen a bit impractical at the moment.

Eco Futurists still promote hydrogen as the replacement for fossil fuels. Many are banking on common green algae that excrete hydrogen when deprived of certain nutrients. Scientists are currently working on making the algae more productive at producing the hydrogen in a lab setting.

Essentially, solar is the best option for residential, off grid technology. While wind has the potential to be very effective, most residential environments do not work well with wind due to scale logistics (unless you live way out in the country). Hydrogen fuel cells look great for the future of energy production, but the technology is not yet there today to make it truly sustainable


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