EAAC0423 Environmental Science & Engineering Lecture Notes PDF

BA TA A N P ENINSULA STA TE UNIVERSITY C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE D e par tm e nt o f Me c hani c al Eng i ne e r i ng EAAC0423 Environmental Science and Engineering BSME...

BA TA A N P ENINSULA STA TE UNIVERSITY C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE D e par tm e nt o f Me c hani c al Eng i ne e r i ng EAAC0423 Environmental Science and Engineering BSME (3A, 3B, 3C) Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY The capacity to do work. They can exist in numerous forms and their sum constitutes the total energy of a system. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Main Types of Energy 1. Kinetic Energy ⚬ The energy that a system possesses as a result of its motion relative to some reference frame 2.Potential Energy ⚬ The energy that a system possesses as a result of its elevation in a gravitational field Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY Interactions 1. Heat ⚬ form of energy that is transferred between two systems (or a system and its surroundings) by virtue of a temperature difference. ⚬ An energy interaction is heat only if it takes place because of a temperature difference. ⚬ The direction of energy transfer is always from the higher temperature body to the lower temperature one. Once the temperature equality is established, energy transfer stops. There cannot be any heat transfer between two systems that are at the same temperature. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY Interactions Adiabatic Process ⚬ A process during which there is no heat transfer. ⚬ There are two ways for this process: i. Either the system is well insulated so that only a negligible amount of heat can pass through the boundary, or ii. Both the system and the surroundings are at the same temperature and therefore there is no driving force (temperature difference) for heat transfer. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY Interactions 2. Work ⚬ an energy interaction between a system and its surroundings. ⚬ If the energy crossing the boundary of a closed system is not heat, it must be work. Heat is easy to recognize because its driving force is a temperature difference. ⚬ Then an energy interaction that is not caused by a temperature difference is work. ⚬ More specifically, work is the energy transfer associated with a force acting through a distance. ⚬ A rising piston, a rotating shaft, and an electric wire crossing the system boundaries are all associated with work interactions. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing The first law of thermodynamics or the conservation of energy principle: “Energy can be neither created nor destroyed during a process; it can only change forms.” Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENTHALPY ⚬ the sum of the internal energy and the product of the pressure and volume of a thermodynamic system. ⚬ According to the law of energy conservation, the change in internal energy is equal to the heat transferred to, less the work done by the system. If the only work done is a change of volume at constant pressure, the enthalpy change is exactly equal to the heat transferred to the system. ￭ When energy needs to be added to a material to change its phase from a liquid to a gas, that amount of energy is called the enthalpy (or latent heat) of vaporization and the enthalpy (or latent heat) of fusion for changes from a solid to a liquid. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing SPECIFIC HEAT ⚬ energy required to raise the temperature of a unit mass of a substance by one degree. ￭ Specific heat at constant volume cv: the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is maintained constant. ￭ Specific heat at constant pressure cp: The energy required to do the same as the pressure is maintained constant. ⚬ The specific heat at constant pressure cp is always greater than cv because at constant pressure the system is allowed to expand and the energy for this expansion work must also be supplied to the system. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing Energy System ENERGY DEMAND ENVIRONMENTAL FACTORS ENERGY RESOURCES ENERGY CONVERSION Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY SOURCES Considering the conventional energy sources, the increasing environmental problems and all energy sources alternatives, there can be predicted five essential developments: 1)the conventional energy sources will build also in the future the hard core of energy activities, substituting nevertheless as much as possible petroleum by other energies to strengthen the availability of petroleum into a longer future 2)the new energy sources—alternatives as weak energies will substitute partly the short-term demand on conventional energy sources and take over in the long-term future an increasing but not substantial portion of the total energy demand 3)the transportation and traffic systems of the world, which make a major contribution to environmental degradation, will be converted to new, or alternative energy sources, thus fundamentally changing their nature 4)the protection of environment necessitates for both, the conventional and the new energy technologies, high investment costs which will increase the cost of final energy for the consumer 5)to find out the best combination of conventional energies and energy sources—alternatives of old and new energy technologies and necessities as well as economic possibilities to protect the environment, the countries—and it can be only a national way of solution—must elaborate a long-term planning system like masterplan or energy strategies with computerized instrumentation, a typical task for the national energy commissions. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 1. Land Use 2. Employment and Safety 3. Air Pollutants 4. Water Quality 5. Thermal Effects 6. Radiation 7. Solid Wastes 8. Noise Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 1. Land Use ⚬ Physical space means the tangible dimensions of geography (landforms, climate zones, ecosystems, natural resources, and other physical characteristics) Engr. Andrea Shane M. Torres  BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 2. Employment and Safety ⚬ Workplace safety is key to reducing human and financial losses in the energy sector of the utilities industry. ⚬ Making sure your employees utilize the right tools and equipment is important to improving your workplace. ￭ Renewable Energy Safety and Health Rules and Regulations (RESHERR) Code of Practices (COPs) is primarily intended to guide RE Developers in ensuring safety in the workplace to protect workers from occupational safety and health hazards, thereby ensuring the continuous supply of electricity in the country. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 2. Employment and Safety ⚬ Safety requirements and strategies - adhere to the OSHA guidelines ￭ Safety Orientation: Comprehensive introduction to workplace safety specific to the renewable energy industry. ￭ Emergency Response Training: Procedures for handling emergencies. ￭ Hazard Recognition and Mitigation: Training in identifying, assessing, and mitigating job-specific hazards. ￭ Equipment Operation Certification: For workers operating heavy machinery or specialized equipment. ￭ Fall Protection Training: Particularly essential for workers in the wind and solar sectors who work at heights. ￭ Electrical Safety Training: For all employees handling or exposed to electrical systems. ￭ Lockout/Tagout Procedures: To ensure machinery is safely shut off and unable to start up unexpectedly during maintenance. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ⚬ The Office of Air Programs in the Environmental Protection Agency (EPA), formerly the NAPCA (National Air Pollution Control Administration), provided a compilation of air pollutant emission factors which give the average quantity of pollutants released in the operation of various fuel- energy conversion system combinations. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ￭ Carbon Monoxide This poisonous gas is produced by the incomplete combustion of carbon in fuels. When combustion conditions are well controlled and excess air can be provided, combustion is generally complete, and CO2 is produced with only trace amounts of CO. Proper design of the combustion chamber to prevent regions of insufficient air and by providing residence time and temperature conditions that will allow conversion of all of the CO to CO2. In cases where combustion conditions cannot be adequately controlled to permit complete conversion, the exhaust gases may be reacted with air either thermally or catalytically to complete the reaction to CO2. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ￭ Particulates Any matter, solid or liquid, in which individual particles are larger than molecular size but smaller than 500 microns. ⚬ Dust, pollen, soot, smoke, and liquid droplets ⚬ In coal power plants, fly ash is type of particulate release and consists of carbon, silica, alumina, and iron oxide Particulate matter in the atmosphere has adverse effects on materials and health and will have long-term effects on the thermal energy balance of the earth. It provides condensation nuclei which can increase cloud cover and thereby reflect more of the solar energy input to the earth back into space. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ￭ Sulfur Dioxides SO2 is produced in the combustion of sulfur-bearing fuels such as coal and residual oil and is released to the atmosphere in the flue gases from power plants using these fuels. ⚬ Sulfur dioxide emissions may be controlled by fuel selection using either low sulfur fuels or by removing the sulfur from the fuel before burning it ⚬ A catalytic oxidation process, based on the technology of sulfuric acid production, that captures sulfur emissions as SO3 in a weak acid solution is also quite promising. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ￭ Oxides of Nitrogen, Hydrocarbons, and photochemical oxidants NO and reactive organic substances such as hydrocarbons (HC), when exposed in the atmosphere to solar ultraviolet radiation, form photochemical smog. ⚬ Photochemical smog - It contains anthropogenic air pollutants, mainly ozone, nitric acid, and organic compounds, which are trapped near the ground by temperature inversion. These pollutants and also some others can affect human health and cause damage to plants. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 3. Air Pollutants ￭ Carbon Dioxide It is a strong absorber in the infrared region of the electromagnetic spectrum, a region where much of the energy that the earth loses by radiation to space is concentrated. The CO2 absorbs this energy, reradiating it in turn to space at a lower source temperature. This mechanism effectively reduces the heat loss from the earth and causes its temperature to increase. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 4. Water Quality ￭ Discharges of waste heat can be controlled by improving the thermal efficiency of power plants, and the severity of local effects may be reduced by distributing the waste energy in large quantities of air or water 5. Radiation ￭ In the nuclear industry radiation problems begin with the mining of uranium-bearing ores. The alpha particle emitters, particularly radon gas, in the uranium-238 decay chain that ends with stable lead-206 pose the major health problem. Radon is chemically inert and diffuses from rock surfaces into the mine atmosphere where it and its daughter products can be inhaled by workers. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 7. Solid Wastes ￭ Large amounts of solid wastes are generated in coal mining, uranium mining, and shale oil recovery. The residual wastes from the processing of coal are put in culm banks and coal waste piles. Over 30 million tons of fly ash were recovered from power plants burning coal and lignite. About 20% of this is used commercially as a soil conditioner and as an additive to concrete and asphalt mixes. Bottom ash, which accounts for about one-fifth of the ash produced in coal-fired plants, is used in the manufacture of cinder blocks, as road ballast, and on highways in icy weather. Unused portions of these materials represent a solid waste disposal problem and are dumped in spoil areas which occupy land are unsightly. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENVIRONMENTAL FACTORS 8. Noise ￭ Energy conversion devices, particularly those used for mobile applications, are noisy in operation. Noise can impair hearing and has physiological and psychological effects on people. The average level of sound at normal conversation amounts to 55 db (A) in a distance of 3 feet. ￭ For the noise in a living room a level of 35–40 db (A) is acceptable, the critical level of noise begins with 40 db (A), above 40 db the noise can reduce the attention and concentration of working people. ￭ For working places they are required by law to limit the noise level to: ⚬ 1) mainly intellectual work 55 db (A). ⚬ 2) simple or mainly mechanical office work 70 db (A). ⚬ 3) all other work in office or workshop 85 db (A). From 90 db (A) on it is required to wear ear protection. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES 1. Hydropower 2. Geothermal Sources 3. Sun 4. Biomass 5. Natural gas and liquids 6. Refuse Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES 1. Hydropower ￭ Hydropower is the most important of the regeneratable energy sources because of its highest efficiency at the energy conversion. There are two types of hydroelectric power plants: ⚬ 1) Run-of-river power plants for the use of affluent water; ⚬ 2) Storage power plants (power stations with reservoir) where the influx can be regulated with the help of a reservoir. ￭ Working Principle: It utilizes the potential energy of water stored in a dam built across the river. The potential energy of the stored water is converted into kinetic energy by first passing it through the penstock pipe. The kinetic energy of the water is then converted into mechanical energy in a water turbine. The turbine is coupled to the electric generator. The mechanical energy available at the shaft of the turbine is converted into electrical energy by means of the generator. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES 2. Geothermal Sources ￭ The temperature of earth increases with depth at the rate of about 2°F every 100 feet in rock and at about 3 times the rate near natural steam sources. The thermal energy in deep underground zones can be recovered either by tapping natural steam or hot water sources, or by fracturing dry hot rock formations and flooding them with water to generate steam for use in a conventional steam-electric power plant. ￭ Working Principle: The process of capturing geothermal energy involves using geothermal power plants or geothermal heat pumps to extract high-pressure water from the underground. After reaching the surface, the pressure is lowered and the water converts to steam. The steam rotates turbines that are connected to a power generator, thereby creating electricity. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES 3. Sun (Solar) ￭ The rate at which solar energy intercepts the diametral plane of the earth is about 17.7 x 10^10 MW. ￭ Solar panels, also known as photovoltaics, capture energy from sunlight, while solar thermal systems use the heat from solar radiation for heating, cooling, and large-scale electrical generation. 4. Biomass ￭ In ecology, it means living organisms, and in bioenergy, it means matter from recently living organisms. In the latter context, there are variations in how biomass is defined, e.g. only from plants, from plants and algae, from plants and animals. ￭ It contains stored chemical energy from the sun that is produced by plants through photosynthesis. Biomass can be burned directly for heat or converted to liquid and gaseous fuels through various processes. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY RESOURCES 5. Natural Gas and Liquids ￭ Natural gas resources are classified into non-associated, associated, and dissolved categories depending on whether the gas exists alone, in a gas cap with oil beneath it, or dissolved in oil. Methane is the principal component of natural gas delivered to the consumer. ￭ Natural gas liquids (NGL) are recoverable from the gas and supplement other liquid fuel resources 6. Refuse ￭ This type of energy source is derived from solid waste (paper, rags, cardboard, and plastics). ￭ Combustible wastes may be used as a fuel for electric power production and process heat and have a heating value of about 5000 Btu/lb. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY CONVERSION 1. Centralized and Decentralized Power Plants 2. Fuel Cells 3. Magnetohydrodynamics Energy Strategies Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY CONVERSION 1. Centralized and Decentralized Power Plants ￭ Electrical energy is generated in large-centralized facilities for distribution to consuming activities. The demand for electrical energy varies on a daily, weekly, and seasonal cycle. The installed generating capacity must match the peak demand and some of this capacity must be idle during periods of low demand. Electric generating plants with an output of over 1000 MW. ￭ Energy conversion systems currently utilized in DPP involve mainly combustion devices for space heat and industrial process heat applications. Decentralized electric power generating facilities of up to 5 MW output (installed in shopping centers and housing complexes) Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY CONVERSION 2. Fuel Cells ￭ This direct conversion device can convert chemical energy directly into electrical energy without the intermediate conversion to thermal and kinetic energy. ￭ With hydrogen and oxygen fuel fed to electrodes submerged in a suitable electrolyte, this device produces 0.7 to 0.85 volts (dc)/cell and many cells must be connected in series to produce useful voltages for transmission. ￭ Development work is in progress on cells that could operate on gasified coal or other gaseous fuels with air as the oxidizer and a conceptual design has been completed for such a plant. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY CONVERSION 3. Magnetohydrodynamics ￭ MHD generators can utilize either a fossil or nuclear thermal energy source. In a fossil fueled system, hot combustion gases, seeded with potassium or cesium to make the gas conductive, are expanded at high velocity through a magnetic field. The dc current produced in the moving conductive gas is picked up at electrodes embedded in the walls of the gas channel in various geometries depending upon the particular type of generator. ￭ The advantage of this system is its high thermal efficiency of 50 to 60% when operated at a gas temperature in the 4000° to 5000°F range. Engr. Andrea Shane M. Torres BA T A A N P EN I N S U L A S T A T E U N I V ERS I T Y EAAC0423 C O L LE GE O F E N G I N E E RI N G A N D A RC H I T E C T U RE Environmental Science and Engineering De p a r tm en t o f M e c h a ni cal E n g i n e e r ing ENERGY STRATEGIES 1. A long-range development plan for the energy system in terms of exploitation and extraction capacities, energy conversion and production capacities, total demand in relation to capital investment and population growth. 2. Annual consumption of primary energy and its structure. 3. An energy flow diagram. 4. Annual costs for each operation in the energy system. 5. Equipment requirements for each process and the additional capacity investment. 6. Ratio of indigenous to imported energy. 7. Sites for new plants. 8. Effects of new technologies on the energy system. Engr. Andrea Shane M. Torres BA TA A N P EN I N SUL A STA TE UN I VERSI TY EAAC0423 C OL L EG E OF EN G I N EERI N G A N D A RC H I TEC TURE Environmental Science and Engineering D epar tment of Mec hani c al Eng i neer i ng