F.Sc./ICS Part 1 Physics Notes by Luqman Saleem BS Hons Physics - email: luqmansaleem99@gmail.com Non-conventional energy sources: Energy sources which are not very common these days are called non-conventional energy source. For example: Energy from tides Energy from waves Energy form biomass Geothermal energyEnergy from tides:Moon produces tides on earth twice a days, these tides can be used to produce electricity by building a basin in the ocean. As shown in figure at page 32.Energy from waves:Wind produces waves in ocean. These waves can be used to produce electricity using salters duck, salters duck consist of two parts, Duck float and Balance float. Balance float balance the device and duck float move to produce electricity.Solar energy:Sun give almost 1.4 kW/m^2 energy to earth. This is called solar constant. This energy reduces to 1 kW/m^2 when it reaches at surface of earth due to loss with dust & gas particles. Solar energy can be used to produce electricity using solar cells; solar cells are made from Semi-conductor materials that convert solar energy into electricity. Solar cells are also called Voltaic cells.Solar energy can be used to heat the water directly, as device showed at page 93. It has a blacked surface which absorbs energy from sun, cold water passes on the surface and heat up to 70 CUses of solar energy:Solar cells use in satellites, solar calculators, solar watches, weather stations.Energy from biomass:Getting energy from waste materials like animal dung, crop residue, trees is called biomass energy.It has two methods:Direct combustion: in this process material is burnt to get heat energy directly.Fermentation: in this process waste material is rotted in closed tanks called digester that produces biogas.Energy from waste products: in this process material is burnt to get heat energyGeo thermal energy:Heat energy in earth is called geo thermal energy. Energy in earth is due to following process: Radioactive decay: energy is constantly being released by the decay of radioactive materials Residual heat of the earth: within 10km of earths surface there are partly molten rocks with temperature 200C or more. This is a heat energy. Compression of material: compression of materials deep inside earth also generate heat energyThis heat produce steam that is used to run turbines and that turbines produce electricity.Geyser:A spring which discharges hot water and steam is called geyser. The geysers releases an explosive column into the air. Most geysers erupt at irregular intervals. They usually fount in volcanic regions.

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