Pharos University جامعه فاروس Faculty of Engineering كلية الهندسة Petrochemical Department قسم البتروكيماويات PE 330 ENERGY CONSERVATION LECTURE (10) Renewable Energy Sources Renewable energy sources also called non-conventional energy, are sources that replenish themselves, and are continuously present. A renewable energy system converts the energy found in sunlight, wind, falling-water, sea- waves, geothermal heat, or biomass into a form, we can use such as heat or electricity.

However, most of the world's energy sources are derived from conventional sources-fossil fuels such as coal, oil, and natural gases. These fuels are often termed non-renewable energy sources. Although, the available quantity of these fuels are extremely large, they are nevertheless finite and so will in principle ‘run out’ at some time in the future Renewable energy sources are essentially flows of energy, whereas the fossil and nuclear fuels are, in essence, stocks of energy. They supply about 3% of worlds energy, on the other hand, fossil fuels supply 90%, and nuclear 7%.

2-Various forms of renewable energy Solar energy Wind energy Biomass energy Hydroelectric energy Geothermal energy Tidal/Oceanic energy Waste to energy

2.1 Solar energy Sunlight is the most abundant energy source on the earth On average, the earth's surface receives about 1.2 x W of solar power. Solar energy is utilized in three ways: Passive heating Active heating Solar generated electricity

2.1.1 Solar passive heating  Suns energy is converted directly to heat energy when it is absorbed by a surface based on design, construction materials, energy is captured and used on site.  No moving parts  No energy is used to transfer heat within system.  No operating costs.  Practical only in new constructions.

2.1.2 Solar Active Heating:  Suns energy is converted into heat, but transported elsewhere to be used.  It requires the following: Solar collector Pump System of pipes  Operation and maintenance costs are high.

 Solar collectors transfers suns energy to liquid filled tubes.  Tubes carry warm liquid to area to be heated.  Heat from liquid filled tubes is transferred to areas to be heated or transferred to water that needs to be heated.  Heat developed liquid in liquid-filled tubes is re- circulated to solar collectors.

2.1.3 Solar generated electricity:  Process of converting solar energy directly into electrical energy by use of photovoltaic (PV) cell.  Sunlight energizes electrons, in a transparent wafer containing a semi conductor material, causing the electrons to flow, creating electrical current that produces tiny amount of energy.  To produce significant amount of electricity, many semi conductors must be wired together in modular panels.

2.2 Hydro-electric Energy Using flowing water to generate electricity. It is used widely nowadays. It was used before to power some machines as: Grain mills Saw mills Machines for textile industry

2.3 Tidal and Ocean Energy: Tidal energy: The head of water is then used to drive turbines to generate electricity from the elevated water in the basin as in hydroelectric dams. Ocean Energy : Oceans cover more than 70% of Earth’s surface, making them the world’s largest solar collectors. Ocean energy draws on the energy of ocean waves, tides, or on the thermal energy (heat) stored in the ocean. The sun warms the surface water a lot more than the deep ocean water, and this temperature difference stores thermal energy. The ocean contains two types of energy: thermal energy from the sun’s heat, and mechanical energy from the tides and waves. Ocean thermal energy is used for many applications, including electricity generation.

2.4 Wind Energy: Wind contains kinetic energy The higher the wind speed,the higher the kinetic energy Kinetic energy of the wind → rotor( blades with an aerodynamic profile) → transmits the rotational motion via a gear set to the generator → power

2.5 Geothermal energy Earths core temperature is about 4400 ºC Natural heat extracted from the earth's crust,which originates deep in the earth's molten interior, responsible for volcanoes and earthquakes in some areas is close to the surface. This heat could heat underground water and form steam used to generate electricity.

2.6 Biomass Energy: Biomass is any accumulation of organic material produced by living organisms. Utilization of organic waste to produce energy Chemical energy stored in plants and animals or in the animal waste is called bio-energy Burning of the biomass will release the energy which can be used as: Source of heat Produce electricity Converted to alcohol Used to produce methane.

2.7 waste to energy: It is defined as the use of municipal waste as a source of energy. Waste energy concerns with: Air pollution Formation of toxic compounds such as toxins.