RENEWABLE ENERGY RESOURCES Prepared by Engr. JP Timola Reference: Renewable Energy Resources by J Twidell
History of Energy Usage 1700 s - almost all our energy came from wind, water, firewood, or muscle power. Wind powered the windmills and sailing ships. Water powered water wheels. Firewood did cooking and heated homes. Muscle power (human or animal) for everything else. 1800 s ground 1900 s began. - energy from coal dug out of the - drilling for oil and natural gas
History of Energy Usage 1950 s - fossil fuels had mainly displaced the older energy sources except for water power. Fossil fuels come from the decayed remains of prehistoric plants and animals After 1950 s - use of atomic energy from uranium dug from the ground. Present - use of older renewable energy sources has increased and have begun to use new renewable energy sources as well.
What are renewable resources? natural resources that can be replenished in a short period of time True renewable energy sources are energy supplies that are refilled by natural processes at least as fast as we use them. Renewable energy supplies can become exhausted if we use them faster than they become replenished
What are renewable resources? also be called Green Energy or Sustainable Energy If used wisely, however, renewable energy supplies can last forever.
Can you give examples of renewable energy
What are non-renewable resources? Sometimes know as alternative energy Energy obtained from static stores of energy that remain underground unless released by human interaction Examples are nuclear fuels and fossil fuels of coal, oil and natural gas.
What are non-renewable resources? energy that is initially an isolated energy potential, and external action is required to initiate the supply of energy for practical purposes. such energy supplies are called finite supplies or Brown Energy.
Can you give examples of nonrenewable energy?
Renewable and Non-renewable Energy
ENERGY SOURCES Five ultimate primary sources of useful energy 1 The Sun. 2 The motion and gravitational potential of the Sun, Moon and Earth. 3 Geothermal energy from cooling, chemical reactions and radioactive decay in the Earth. 4 Human-induced nuclear reactions. 5 Chemical reactions from mineral sources.
Natural energy currents on earth
Three broad divisions of Renewable energy supply systems 1 Mechanical supplies, such as hydro, wind, wave and tidal power. The mechanical source of power is usually transformed into electricity at high efficiency. The proportion of power in the environment extracted by the devices is determined by the mechanics of the process, linked to the variability of the source. The proportions are, commonly, wind 35%, hydro 70 90%, wave 50% and tidal 75%.
Three broad divisions of Renewable energy supply systems 2 Heat supplies, such as biomass combustion and solar collectors. These sources provide heat at high efficiency. However, the maximum proportion of heat energy extractable as mechanical work, and hence electricity, is given by the second law of thermodynamics and the Carnot Theorem, which assumes reversible, infinitely long transformations. In practice, maximum mechanical power produced in a dynamic process is about half that predicted by the Carnot criteria. For thermal boiler heat engines, maximum realisable quality is about 35%.
Three broad divisions of Renewable energy supply systems 3 Photon processes, such as photosynthesis and photochemistry and photovoltaic conversion. For example, solar photons of a single frequency may be transformed into mechanical work via electricity with high efficiency using a matched solar cell. In practice, the broad band of frequencies in the solar spectrum makes matching difficult and photon conversion efficiencies of 20 30% are considered good.
Pollution and environmental impact As results of using brown fuels, fossil and nuclear, harmful emissions can be classified as chemical (as from fossil fuel and nuclear power plant) physical (including acoustic noise and radioactivity) biological (including pathogens); such pollution from energy generation is overwhelmingly a In contrast, renewable energy is always extracted from flows of energy already compatible with the environment. energy is then returned to the environment, so no thermal pollution can occur on anything but a small scale. material and chemical pollution in air, water and refuse tend to be minimal. exception is air pollution from incomplete combustion of biomass or refuses.
Pollution and environmental impact Environmental pollution does occur if brown energy is used for the materials and manufacture of renewable energy devices, but this is small over the lifetime of the equipment. The environmental impact of renewables depends on the particular technology and circumstances.