T 1

• The word ‘energy’ itself is derived from the Greek word ‘en-ergon’, which means ‘in-work’ or ‘work content’. The work output depends on the energy input.
• Energy can be classified into several types based on the following criteria:

  • Primary and Secondary energy

  • Commercial and Noncommercial energy

  • Renewable and Non-Renewable energy

  • Conventional and Non-conventional energy
• Primary energy sources are those that are either found or stored in nature. Common primary energy sources are coal, oil, natural gas, and biomass (such as wood).
• Other primary energy sources available include nuclear energy from radioactive substances, thermal energy stored in earth's interior, and potential energy due to earth's gravity.
• Primary energy sources are costly converted in industrial utilities into secondary energy sources; for example coal, oil or gas converted into steam and electricity.
• Primary energy can also be used directly. Some energy sources have non energy uses, for example coal or natural gas can be used as a feedstock in fertilizer plants.
• 
  

  The energy sources that are available in the market for a definite price are known as commercial energy. By far the most important forms of commercial energy are electricity, coal and refined petroleum products.
• Commercial energy forms the basis of industrial, agricultural, transport and commercial development in the modern world. In the industrialized countries, commercialized fuels are predominant source not only for economic production, but also for many household tasks of general population.
• Commercial Energy

  Electricity, lignite, coal, oil, natural gas etc.
• 
  

  The energy sources that are not available in the commercial market for a price are classified as non-commercial energy.
• Non-commercial energy sources include fuels such as firewood, cattle dung and agricultural wastes, which are traditionally gathered, and not bought at a price used especially in rural households. These are also called traditional fuels. Non-commercial energy is often ignored in energy accounting.
• Non-Commercial Energy

  Examples: Firewood, agro waste in rural areas; solar energy for water heating, electricity generation, for drying grain, fish and fruits; animal power for transport, threshing, lifting water for irrigation, crushing sugarcane; wind energy for lifting water and electricity generation.
• Renewable Energy

  Energy sources, which are continuously and freely produced in the nature and are not exhaustible are known as the renewable sources of energ
• Under Philippine Presidential Decree 1068 enacted in 1977, it is broadly defined as energy resources in which the conversion or utilization technology for largescale applications are not well developed and/or widely used ex. solar, wind, micro hydro (5 up to 100 kw), biomass (manure, rice hull, farm waste, etc.), ocean thermal, tidal, etc.
• Renewable energy sources derive their energy from existing flows of energy from on-going natural processes, such as sunshine, wind, flowing water, biological processes, and geothermal heat flows.
• Renewable energy is captured from an energy resource that is replaced rapidly by a natural process such as power generated from the sun or from the wind
• Renewable Energy

  That type of energy is passing through the environment irrespective of there being a man made device to intercept and harness the power. This is also referred as non-conventional sources of energy.”
• Non-renewable energy is the conventional fossil fuels such as coal, oil, gas, which are likely to deplete with time.
• Non-renewable Energy

  That type of energy is initially in an isolated energy potential and external action is required to initiate the supply of energy for practical purposes. This type of energy is also sometimes called finite energy or conventional sources of energy.
• Renewable and Nonrenewable

  
• Conventional Energy

  all other energy resources, renewable or not, which are not classified as non-conventional ex. gasoline, kerosene, coal, natural gas, mini and big hydros (>100 kw), nuclear, etc
• 
  

  Under recent Philippine non-conventional energy program, non-conventional energy system is limited in scope and is specifically defined as energy system that can be characterized as using renewable resource, indigenous or resource used is locally available, small-scale, decentralized and modular or easily sized to meet energy demand
• Major non-conventional energy systems

  1. Biogas plant
  2. Wind pump
  3. Solar home systems (SHS)
  4. Solar battery charging stations (BCS)
  5. Micro hydro power plants (100 kw and below)
• Fossil fuels

  Advantages

  • Provide a large amount of thermal energy per unit of mass

  • Easy to get and easy to transport

  • Can be used to generate electrical energy and make products, such as plastic

  Disadvantage

  • Nonrenewable

  • Burning produces smog

  • Burning coal releases substances that can cause acid precipitation

  • Risk of oil spills
• Nuclear

  Advantages

  • Very concentrated form of energy

  • Power plants do not produce smog

  Disadvantages

  • Produces radioactive waste

  • Radioactive elements are nonrenewable
• Solar

  Advantages

  • Almost limitless source of energy

  • Does not produce air pollution

  Disadvantages

  • Expensive to use for large-scale energy production

  • Only practical in sunny areas
• Water

  Advantages

  • Renewable

  • Does not produce air pollution

  Disadvantages

  • Dams disrupt a river’s ecosystem available only in areas that have rivers
• Wind

  Advantages

  • Renewable

  • Relatively inexpensive to generate

  • Does not produce air pollution

  Disadvantages

  • Only practical in windy areas
• Geothermal

  Advantages

  • Almost limitless source of energy

  • Power plant require little land

  Disadvantages

  • Only practical areas near hot spots

  • Waste water can damage soil
• Biomass

  Advantages

  • Renewable

  Disadvantages

  • Requires large area of farmland

  • Produces smoke
• Solar Energy Modern residential solar power systems use photovoltaic (PV) to collect the sun’s energy
• “Photo” means “produced by light,” and “voltaic” is “electricity produced by a chemical reaction.”
• PV cells use solar energy to generate a chemical reaction that produces electricity.
• Solar Energy

  
• Wind Energy

  a form of solar energy and is caused by the uneven heating of the atmosphere by the Sun, the irregularities of the Earth’s surface, and rotation of the Earth. The amount and speed of wind depends on the Earth’s terrain and other factors.
• Wind energy is a clean and renewable source of power. The use of windmills to generate energy has been utilized as early as 5000 B.C., but the development of wind energy to produce electricity was sparked by the industrialization
• The wind turbines use the kinetic energy of the wind and convert that energy into mechanical energy, which in turn can be converted into electricity by means of a generator.
• Wind Energy

  
• The earliest reference to the use of the energy of falling water is found in the work of the Greek poet Antipater in the 4th century BC.
• The word “hydro” comes from the Greek language meaning “water.” Several centuries later, the Romans were the first to utilize the waterwheel