Chapter 4 Carbon dioxide (CO2) is not a pollutant that would harm our health but it is a proven greenhouse gas. High concentrations of SO2 can result in temporary breathing impairment for asthmatic children and adults who are active outdoors. Short-term exposures of asthmatic individuals to elevated SO2 levels during moderate activity may result in breathing difficulties that can be accompanied by symptoms such as wheezing, chest tightness, or shortness of breath. Carbon in the fuel combines with the oxygen in the air used for burning and forms carbon dioxide. If there is not enough oxygen for complete oxidation, carbon monoxide (CO) may form. The United States continues to be the largest single emitter of fossil fuelrelated CO2 emissions reaching an all-time high of 1,529 million metric tons of carbon in 2000. Methane is a greenhouse gas formed due to decomposition of organic wastes, formed in land fills, and during raising livestock. It is also a major component of natural gas, which is formed as result of decomposition of plants millions of years ago. CO2 is a greenhouse gas which has an ability to absorb infrared radiation that is escaping from the surface of the earth causing the atmosphere to warm up. SO2 is not. The pollutants that are emitted directly from a combustion process are called &quot;primary pollutants.&quot; Ozone is a secondary pollutant. The United States continues to be the largest single emitter of fossil fuelrelated CO2 emissions reaching an all-time high of 1,529 million metric tons of carbon in 2000. Nitrogen oxides can form from both nitrogen in the fuel and nitrogen in the air used for combustion. The highest levels of CO in the outside air typically occur during the colder months of the year when inversion conditions are more frequent. An inversion is an atmospheric condition that occurs when the air pollutants are trapped near the ground beneath a layer of warm air. Most of the emissions from combustion devices (approximately 90%) are in the form of NO. SO2 dissolves in water vapor to form acid, and interacts with other gases and particles in the air to form sulfates and other products that can be harmful to people and their environment. SO2 does not contributes to the formation of ground level ozone. NOx contributes to a wide range of environmental effects directly and when combined with other precursors in acid rain and ozone. SO2 is not involved. Carbon dioxide is formed when all fossil fuels are burned. Chapter 5 (9) A water heater heats 151 gal of water from 54oF to 137oF every day. What is the annual energy requirement of the water heater? Annual energy requirement = 151 * (137 - 54) * 8.3 * 365 = 37968723.5 BTUs. Note: 1 gal of water weighs 8.3 lbs. Natural gas water heaters cost more to install than electric water heater. An old refrigerator consumes 187 W of power. Assuming that the refrigerator operates for 17 hours every day, what is the annual operating cost of the refrigerator, if the cost of electricity is $0.06 per kWh? Annual operating cost = 187 / 1000 * 17 * 0.06 * 365 = $69.6201. Using a low flow non-aerating showerhead can cut water consumption by about 50%. Energy Factor (EF) is used to define the energy efficiency of a dishwasher. Demand water heaters are in-line heaters and don't have a storage tank. You can save up to 1/3 of your dishwasher operating costs by allowing the dishes to air dry rather than go through the dry cycle. Demand water heaters are in-line heaters and don't have a storage tank. An old refrigerator consumes 236 W of power. Assuming that the refrigerator operates for 18 hours every day, what is the annual operating cost of the refrigerator, if the cost of electricity is $0.05 per kWh? Annual operating cost = 236 / 1000 * 18 * 0.05 * 365 = $77.526. A water heater heats 193 gal of water from 55oF to 129oF every day. What is the annual energy requirement of the water heater? Annual energy requirement = 193 * (129 - 55) * 8.3 * 365 = 43267319 BTUs. Note: 1 gal of water weighs 8.3 lbs. An old refrigerator consumes 198 W of power. Assuming that the refrigerator operates for 15 hours every day, what is the annual operating cost of the refrigerator, if the cost of electricity is $0.11 per kWh? Annual operating cost = 198 / 1000 * 15 * 0.11 * 365 = $119.2455. Highly energy efficient appliances have an Energy Star label. Calculate the amount of heat energy required to heat 126 lbs of water from 62oF to 121oF. Amount of heat energy required = 126 * (121 - 62) = 7434 BTUs. Calculate the amount of heat energy required to heat 185 lbs of water from 61oF to 134oF. Amount of heat energy required = 185 * (134 - 61) = 13505 BTUs. For most efficient operation, keep the freezer filled to capacity. Chapter 6 (10) A 120 watt <a href="/keyword/incandescent-light/" >incandescent light</a> bulb is operated for 6 hours, and a 15 watt fluorescent light bulb is operated for the same period of time. At 8 cents per kWh, what is the cost savings of the fluorescent bulb? Energy consumed by <a href="/keyword/incandescent-light/" >incandescent light</a> bulb = 120 / 1000 * 6 = 0.72 kWh Energy cost for <a href="/keyword/incandescent-light/" >incandescent light</a> bulb = 0.72 * 8 / 100 = $ 0.0576 (round up to $0.06) Energy consumed by Fluorescent light bulb = 15 / 1000 * 6 = 0.09 kWh Energy cost for Fluorescent light bulb = 0.09 * 8 / 100 = $ 0.0072 (round up to $0.01) Cost Savings = $ 0.06 - $ 0.01 = $ 0.05 Fluorescent bulb is usually filled with a mixture of inert gases and mercury. A 150-watt light bulb is operated for 37 hours. How much does it cost to operate the light bulb if electricity costs 12 cents per kWh? Energy consumed = 150 / 1000 * 37 = 5.55 kWh Cost to operate = 5.55 * 12 / 100 = $0.67 Compact fluorescent lamps are 2-4 times more efficient than incandescent lamps. To save energy and money, Jackie Smith replaced a 100 Watt <a href="/keyword/incandescent-light/" >incandescent light</a> bulb in her house with a 23 Watt CFL bulb. The expected life of incandescent and CFL bulbs is 1000 and 8000 hours respectively. The purchase price of an incandescent bulb is $0.61 and for the CFL it is $6.09. The cost of electricity is 7 cents per kWh. What is her total savings over the life time of the CFL? CFL energy cost for 8000 hrs = 23 / 1000 * 8000 * 7 /100 = $12.88 Total cost for CFL = 6.09 + 12.88 = $18.97 <a href="/keyword/incandescent-light/" >incandescent light</a> energy cost for 8000 hrs = 100 / 1000 * 8000 * 7 /100 = $56 Number of Incandescent bulbs required = 8000 / 1000 = 8 bulbs Lower wattage bulbs are more efficient than high wattage bulbs. Compared to ordinary incandescent bulbs, tungsten halogen bulbs consume lesser power to produce same amount of light. Fluorescent and High Intensity Discharge light require a ballast to operate. Fluorescent light operates at much lower wattage to produce the same amount of light compared to <a href="/keyword/incandescent-light/" >incandescent light</a> . A 60-watt light bulb produces 4.5 watts of radiant energy and 55.5 watts of heat energy. What is its efficiency? Efficiency = Useful output energy / Total input energy * 100 Efficiency = 4.5 / 60 * 100 = 7.5% A 60-watt light bulb produces 6 watts of radiant energy and 54 watts of heat energy. What is its efficiency? Efficiency = Useful output energy / Total input energy * 100 Efficiency = 6 / 60 * 100 = 10% A 16 watt compact fluorescent lamp produces 1112 lumens of light. What is the efficacy of the CFL (in lumens/watt)? Efficacy = 1112 / 16 = 69.5 lumens/watt Mercury vapor filled bulbs are energy efficient. To save energy and money, Jackie Smith replaced a 100 Watt <a href="/keyword/incandescent-light/" >incandescent light</a> bulb in her house with a 23 Watt CFL bulb. The expected life of incandescent and CFL bulbs is 1000 and 8000 hours respectively. The purchase price of an incandescent bulb is $0.65 and for the CFL it is $5.60. The cost of electricity is 7 cents per kWh. What is her total savings over the life time of the CFL? CFL energy cost for 8000 hrs = 23 / 1000 * 8000 * 7 /100 = $12.88 Total cost for CFL = 5.6 + 12.88 = $18.48 <a href="/keyword/incandescent-light/" >incandescent light</a> energy cost for 8000 hrs = 100 / 1000 * 8000 * 7 /100 = $56 Number of Incandescent bulbs required = 8000 / 1000 = 8 bulbs Total cost for <a href="/keyword/incandescent-light/" >incandescent light</a> = (0.65 * 8) + 56 = $61.2 Total Savings = 61.2 - 18.48 = $42.72 To save energy and money, Jackie Smith replaced a 150 Watt <a href="/keyword/incandescent-light/" >incandescent light</a> bulb in her house with a 32 Watt CFL bulb. The expected life of incandescent and CFL bulbs is 1000 and 8000 hours respectively. The purchase price of an incandescent bulb is $0.63 and for the CFL it is $5.70. The cost of electricity is 7 cents per kWh. What is her total savings over the life time of the CFL? CFL energy cost for 8000 hrs = 32 / 1000 * 8000 * 7 /100 = $17.92 Total cost for CFL = 5.7 + 17.92 = $23.62 <a href="/keyword/incandescent-light/" >incandescent light</a> energy cost for 8000 hrs = 150 / 1000 * 8000 * 7 /100 = $84 Number of Incandescent bulbs required = 8000 / 1000 = 8 bulbs Total cost for <a href="/keyword/incandescent-light/" >incandescent light</a> = (0.63 * 8) + 84 = $89.04 Total Savings = 89.04 - 23.62 = $65.42