Ask Energenie(February 2000) |
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1. ?What are fuel cells and how do they work?"Fuel cells are electrochemical devices that convert conventional fuel sources such as natural gas, hydrogen, and methanol into electricity," said Richard Nelson, extension specialist in energy at Kansas State University. Fuel cells have no moving parts and are similar to a conventional battery, except fuel cells don’t need recharging. In recent years, the most common application for fuel cells has been as a power source for space satellites. Recently, several major automobile manufacturers have begun installing fuel cells in a small quantity of their vehicles and several cities throughout North America have installed fuel cells on buses in their transit system. Fuel cells are also being used, on a limited scale, to supply power to residences and midsize office buildings. Because fuel cells have no moving parts, they can be up to twice as efficient as traditional electrical generation systems (power plants). "Basically, fuel cells make electricity by combining hydrogen contained in the fuel source with oxygen from the outside air," Nelson said. "The only by-products of fuel cell operations are heat, which can be captured and reused, and water vapor." At present, the cost of fuel cells is a major drawback to them being used on a widespread basis, according to Nelson. Average cost of electricity generated from a residential fuel cell is approximately three times the cost of electricity from a conventional power plant, but this is expected to decrease substantially in the next decade. Back to Top |
2. I need to replace my gas water heater. What should I look for in an energy-efficient model?"Energy-saving improvements to water heaters have been slow in coming, but there have been significant upgrades in recent years," said Doug Walter, president of Kansas Building Science Institute, Manhattan. Walter said the cheapest, most common improvement is increased tank insulation. "Energy-efficient heaters typically use urethane foam instead of fiberglass. Foam nearly doubles the insulating value per inch of thickness," he said. Look for a model that has at least 1 1/2 to 2 inches of foam insulation surrounding the tank. "Another feature to consider when shopping for an efficient water heater is the venting system," Walter said. Several manufacturers offer water heaters with sealed combustion venting. These units vent combustion gases horizontally through a nearby wall, eliminating the need for a chimney. Combustion air is brought in through the outer wall of the double-wall flue pipe. Walter said this venting system saves energy because it does not constantly exhaust warm air like a chimney does. Sealed combustion water heaters are more often chosen for their safety than for energy savings. Because they have no connection with the air inside the home, they cannot backdraft or spill harmful pollutants like carbon monoxide into the air you breathe. They are an excellent choice for tightly built new homes. "There also are several high-efficiency models of water heaters that borrow energy-saving technology from high-efficiency furnaces and boilers," he said. "These energy-saving features are electronic ignition and power venting." Electronic ignition eliminates the standing pilot light, which consumes 6,000 to 9,000 cubic feet of natural gas a year. This will save you $25 to $35 in natural gas costs. The advantage of power venting is that it allows more heat to be extracted from the combustion gases, gaining efficiencies as high as 80 to 85 percent. "At the high end in both efficiency and price are water heaters that have efficiencies above 90 percent," Walter said. "Because of their high cost, these models are primarily used as combination space and domestic water heaters. They are used in energy-efficient homes that have very low heating loads." Back to Top |
3. Can you explain to me how an electronic air cleaner works?Electronic air cleaners work on the principle of "static cling." Air entering the air cleaner passes through a charging section consisting of ionizing wires connected to a high-voltage power supply. The charging section strips electrons from dust particles, giving them a positive charge. These charged particles then flow past negatively charged metal plates. Attracted by the negative charge, the particles stick to the plates. Thus, air leaving the air cleaner is practically dust-free. "The process is very efficient because the electrical charges attract even tiny particles," said Doug Walter, president of Kansas Building Science Institute, Manhattan. Furthermore, an electronic air cleaner creates very little resistance to air flow, unlike media filters that work by trapping dust particles in a very dense media. "At air flow rates found in most home heating and air conditioning systems, an electronic air cleaner can remove up to 95 percent of airborne particles as small as .01 micron," he said. To give you an idea of this precision, Walter said the dot above the letter "i" is about 400 microns. As for maintenance on the air cleaner, you must periodically wash the collecting plates to maintain efficiency. "Some units use a pre-filter to remove larger dirt particles before they enter the charging section," Walter said. You can add an electronic air cleaner to your central heating or air-conditioning system, or purchase one as a stand-alone unit for any room. Back to Top |
4. I live in a rural area and need to replace my home's heating unit. I'm considering either an air source heat pump or a propane forced air furnace with a central air conditioning unit. Which will be the best?"The cost of operating either a propane furnace and air conditioner or a heat pump will depend on the efficiency of the equipment, the cost of fuel, the size and performance of the home, and the climate," said Gene Meyer, extension mechanical engineer at Kansas State University. "For this example, assume your home is near Topeka, is built to current practices, and is approximately 2,000 square feet in area." Propane varies in price from about $.60 to $1 per gallon. Propane furnaces' Season Energy Efficiency Rating (SEER) can range from 78 to 96 percent. Your heating costs would vary from about $600 to over $1,200 per year depending on fuel costs and furnace performance. A heat pump's performance is rated by the Heating Seasonal Performance Factor and will range from a minimum of 6.8 to a high of over 10. Winter heating electric rates can be as low as $.045 or as high as $.13 per kilowatt-hour. Your annual heating costs could vary from a low of $400 to a high of $1,700. Cooling costs would be similar for both systems if similar performance equipment was used. "To decide which is best, you will need to determine your fuel costs, and evaluate several performance levels of both systems," Meyer said. "You can contact K-State's Engineering Extension at 785-532-6026 for help in evaluating your particular situation." Back to Top |
5. I can see how using more efficient lighting and appliances reduces energy use, but I've also heard this reduces pollution. How?Most of the electric energy generated in the United States is produced by burning coal. "Even though utility companies have greatly reduced the amount of pollutants released when burning coal, they still release carbon dioxide, nitrous oxides, sulfur oxides and other pollutants to the atmosphere," said Gene Meyer, extension mechanical engineer at Kansas State University. "These harm our environment by increasing greenhouse gasses, contributing to acid rain, and causing smog." By using more efficient lighting, appliances and automobiles, Meyer said you reduce your impact on the environment. For instance, if you replace one 75-watt incandescent light bulb with a 20-watt compact fluorescent light, you reduce the operating cost by about 73 percent. "Over the life of the lamp, the compact fluorescent lamp would save enough energy to keep about a ton of carbon dioxide out of the atmosphere." Meyer said that if you are interested in knowing how much pollution you are helping to generate with your entire electrical use, the Cleaner and Greener Program in Wisconsin has a site on the World Wide Web that will perform all the calculations for you. Here is the address: http://www.cleanerandgreener.org/pollution-from-electricity.htm Back to Top |
6. I've seen several commercials warning about the risk of cancer from radon gas. How can I reduce my risk?"Radon is estimated to be the second leading cause of lung cancer. Your risk depends on the concentration you are exposed to and the length of time you are exposed," said Bruce Snead, extension specialist in residential energy at Kansas State University. "Take the following precautions to lower your risk," he said.
If you would like more information, contact your county extension office, county health department or Engineering Extension at Kansas State University. Back to Top |
7. I need new controls for my outside lights. Can you explain the pros and cons of timers and photocells?If you choose to control your lighting with a timer, you can select from a variety of styles. "The more sophisticated timers adjust to the change in daylight hours throughout the year," said Gene Meyer, extension mechanical engineer at Kansas State University. "The more common timers must be reset manually to keep pace with seasonal shifts in daylight hours." Meyer said the most common criticism of timers is that they may turn on the lights before it gets dark and leave them on longer than necessary. You can avoid this problem without buying the expensive timers that automatically adjust to changes in daylight hours. The answer is a photocell control that responds to daylight by turning on the lights when it gets dark and switching them off in the morning. "The advantage of using photocells is that your lights will be on only during hours of darkness," Meyer said. "However, this may be a disadvantage to businesses using lighting for advertising purposes. It may not be profitable for them to keep the lights on at 2 a.m. when few people will see their sign." What businesses can do to eliminate wasted lighting is use a combination of a timer and a photocell control. To do this, wire the sensor in series with a timer. "In this arrangement, the photocell prevents the light from coming on until it's dark," he said. "Then the timer can shut off the light at the time you specify." Meyer recommended using a timer with either a battery or spring backup to avoid having to reset the timer after every power outage. If your lights are used for security purposes, photocells or the more expensive timers are both suitable alternatives. | Back to Top | Home | |
Ask Energenie is produced by the Kansas Energy Extension Service through Kansas State University. This material was prepared with the support of the U.S. Department of Energy (DOE) Grant No. DE-FG48-97R802102. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily reflect the view of DOE.Mike DorceyEditor Extension Engineering Kansas State University 133 Ward Hall Manhattan, KS 66506-2508 785-532-6026 |