Alternative power systems

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Alternative power systems

Aug 1, 2009 12:00 PM, By Kevin McNamara

Whether you are looking for a reliable backup power system or transitioning to a green-friendly facility, the choices for alternative power systems have never been greater. While approaches using the sun, wind, sub-surface heating and water cause no pollution and little-to-no operational expense once installed, they have been relatively costly to deploy. All of the available alternative power systems available, including fossil fueled units, are inefficient in terms of the actual energy expended versus the electricity produced.

According to the U.S. Energy Information Administration (USEIA), the national average cost for utility delivered power in April 2009 is 9.69 cents per kilowatt/hour (kWH) which is higher than the same average of 9.3 cents in April 2008. While this average rate seems reasonable, the state averages range from less than 6 cents (Wyoming) to almost 19 cents (Hawaii.) In general, the states in New England, the Middle Atlantic and Pacific Coast regions pay the highest for electricity.

Cost considerations

It is necessary to understand the associated costs for materials, installation and maintenance for a system that will meet or exceed the requirements of the application. This provides the basis for calculating the return on investment (ROI).

There are several federal and state tax incentives available to both residential and commercial users who invest in alternative power systems. It will also be possible to sell any excess power generated back to the utility, thus creating additional operational revenue to offset the initial investment. This is called the Avoided Rate and can be obtained from your utility provider. For example, the photovoltaic (PV) panels in a solar power system might generate excess load during periods of peak sun exposure that could be sold back to the utility.

To properly calculate the ROI, obtain a copy of the utility bill for the subject facility and determine the cost per kWH charged. In some cases, the bill may show different costs, based on usage rate levels, discounts, etc. If this is the case, average all the kWH rates; this will be the basis used to compare costs.

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There are several potentially good wind power sites across the U.S. (Click image to enlarge.)

Next determine the percentage of load the alternative power system is expected to offset from the utility delivered power. In most commercial applications it may not be practical or cost effective to consider these systems to operate 100 percent of a facility; however, it might be sensible for lower power transmitter sites. Calculate the kWH the system will provide annually. These systems will perform differently depending on the method chosen and the specific location in the country they are used. This selection of an alternative power system must take into account the environmental factors that would influence proper operation and maximum efficiency.

Finally, the overall cost of the investment will be different depending on the specific power systems, i.e. expected life span of equipment/batteries, fuel costs (if any), system efficiency, cost per kWH, power output, planned outages. Other considerations include the typical financial calculations associated with capital projects such as depreciation, discount rate, investment tax credits and other government incentives. Once these are factored together you will have the real cost of deploying the system.

After you have established your annualized average utility rate (AVR), power output of the alternative system (PO), percentage of contribution that the alternative power system will provide (PC), any excess capacity that can be sold at the Avoided Rate (AR) and the overall cost of the investment in the new power system (OC), the actual cost savings can be computed using: PO � PC � AVR � PO � PC � AR = Actual System Savings. ROI would then equal Actual System Savings / OC.

Alternative power systems

Solar power generation is created through the use of photovoltaic semiconductors that absorb sunlight, subsequently releasing free electrons converted into a usable dc current. Many semiconductors, or solar cells, are installed into a single panel, or module, that supports, protects and electrically combines the cells so they can be installed conveniently. There are several types of manufacturing processes: single-crystal and multi-crystalline are the more traditional methods used over the years, but new processes such as string ribbon silicon and thin-film are easier and cheaper to manufacture and can be made into flexible panels for integration into other materials such as roof tiles for a clean architectural look. The cost of solar panels is dropping significantly and is expected to continue.

Wind power is generated when wind rotates a blade that converts kinetic energy from the wind into mechanical energy. The mechanical energy can be used to power a wide variety of machinery such as a generator, which then provides electrical current. Wind generators should be installed in areas that do not obstruct wind flow, which generally means open land or atop a building as high as possible.

Fuel cells are becoming a popular choice as a backup or in some cases primary power source for communications sites. Fuel cells provide power through an electrochemical reaction using oxygen and a fuel that ultimately yields electricity, water and heat as a byproduct of the electrochemical process. Fuel cells work with a wide variety of fuels but most use hydrogen. Multiple fuel cells or stacks can be combined to achieve high power levels, typically up to 30kW. These systems are eligible for significant tax credits and incentives, have very low operating costs, require minimal space and operate at about 60 percent efficiency.

McNamara is president of Applied Wireless, Cape Coral, FL.