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RENEWABLE RESOURCES

Ammar Salleh English

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RENEWABLE RESOURCES

CHAPTER 1 PRINCIPLES OF RENEWABLE ENERGY
- ENERGY AND SUSTAINABLE DEVELOPEMENT
  - Definition= living, producing and consuming in a manner that meets the needs of the present without compromising the ability of future generations to meet their own needs.
  - Development = improvement in quality of life, and, especially, standard of living in the less developed countries
  - Reliable energy supply = lighting, heating, communications, computers, industrial equipment and transportation
  - Renewable energy supplies are much more compatible with sustainable development than are fossil and nuclear fuels, in regard to both resource limitations and environmental impacts.
  - Numerical Model
    - R=EN
      - R - is the total yearly energy requirement for a population of N people.
      - E - is the per capita energy-use averaged over one year, related closely to provision of food and manufactured goods.
        The unit of E is energy per unit time, i.e. power.
  - Global Resources
    - Appropriate energy use in festyle is E = 2 kW per person.
- FUNDAMENTALS
  - Renewable energy
    - Energy obtained from natural and persistent flows of energy occurring in the immediate environment (Green/Sustainable Energy)
    - Sources = Sun, Earth & Planetary Motion
      - Solar Radiation= Solar energy, Ocean thermal, Hydro, Wind, Wave, Biomass and Biofuels Photovoltaic
      - Geothermal from earth= Geothermal heat & power
      - Gravitation and orbital motion = Tidal range & current power
  - Non-renewable energy
- SCIENTIFIC PRICIPLES
  - Energy Currents
  - Dynamic Characteristics
  - Quality of Supply
    - Photon Processes
    - Heat Supplies
    - Mechanical Supplies
  - Dispersed versus Centralized Energy
  - Complex Systmes
  - Situation Dependence
- TECHNICAL IMPLICATIONS
  - Porspecting the environment
  - End-use requirements and efficiency
  - Matching supply and demand
  - Control options
    - Spill excess energy
    - Incorporate storage
    - Load management control
- SOCIAL IMPLICATIONS
  - Dispersed Living
  - Pollutions and environmental impact
  - Future Generations
CHAPTER 2 SOLAR ENERGY
- Solar Water Heating
  - Active system
  - Passive system
  - Improved solar water heaters
    - Sheltered black container
    - Metal plate collectors with moving fluid
    - Flat plate collector
- Solar Radiation
  - Reach earth's surface at maximum flux density of 1.0 kWm-2 in a wavelength band between 0.3 and 2.5µm (Short Wave Radiation)
  - Sun's surface temperature= 6000K Earth surface 260-300k Atmosphere= 230K
  - Earth energy flux= 1 kWm-2 Infrared Wavelenght= 5-25µm Long wave radiation= 10µm
  - Sun inner temperature= 10^7K Internal radiation 5800K
  - Solar Spectrum
    - Ultraviolet region (  < 0.4µm ) ~ 5% of the irradiance
    - Visible region ( 0.4m <  < 0.7µm ) ~ 43% of the irradiance
    - Infrared region (  > 0.7µm ) ~ 52% of the irradiance
  - Components of radiation
    - Extraterrestrial beam radiation. Earth's surface= Observable. 10% diffuse irradiance in atmosphere
    - Irradiance= amount of solar power/unit area earth suface. Angle and weather is important for direct and diffuse
      - Gbh = G*bcos  z Gt = Gb + Gd
  - Atmospheric absorption and related processes
    - Absorption Scattering Reflections
  - Measurements of solar radiation
- Building and other solar thermal applications
  - Air Heater
  - Energy-efficient buildings
    - Solar passive techniques
      - Direct System Gain
      - Indirect Gain Systems (Thermal Storage Wall)
    - Crop driers
    - Water desalination
    - Solar ponds
    - Solar thermal electric power systems
      - Distributed collectors
      - Power tower
- Photovoltaic Generation
  - Types of material structure
    - -amorphous -polycrystalline -single (or mono) crystalline
  - P–N Junction
  - PV Cell applications
    - Space Systems
    - Solar powered products
CHAPTER 3 HYDRO-POWER
- Principle
  - P0 = ρQgH
  - Assessing the resource for small installations
  - Measurement of head H
    - H a = H t - H f
  - Measurement of flow rate Q
    - Flow rate Q = (volume passing in time ∆t ) / ∆t = (mean speed ū ) × (cross-sectional area A ) =∫ u dA
    - Basic method, Refined method I, Refined method II, Sophisticated method, Using a weir
- Power regulation and control
  - Important that the voltage and frequency of the output match that of the rest of the grid
  - Although the primary generation is always at a relatively low voltage, the AC voltage can easily be increased by transformers, both to match the grid voltage and to minimise I2R losses in transmission
- Hydroelectric systems
  - A complete hydroelectric system, must include the water source, the pipe (penstock), flow control, the turbine, the electric generator, fine control of the generator and wiring for electricity distribution (reticulation)
- Type
  - Reaction turbine
    - the turbine is totally embedded in the fluid and powered from the pressure drop across the device.
      - have a larger flow through the turbine
      - Type
        Francis
        Kaplan
      - the wheel, called the runner, must be adapted so that the fluid enters radially perpendicular to the turbine axis, but leaves parallel to this axis
      - very sensitive to changes in flow rate. The efficiency drops off rapidly if the flow diminishes, because the slower flow no longer strikes the blade at the correct angle
  - Impulse turbine
    - the flow hits the turbine as a jet in an open environment, with the power deriving from the kinetic energy of the flow
      - Potential energy of the water in the reservoir is changed into kinetic energy of one or more jets
        the output power equals the input power, and this ideal turbine has 100% efficiency
        Jet velocity and nozzle size= A=na
        Angular velocity and turbine size
        The latter is determined by geometric constraints, and also by the required rotational speed. For electrical generation, the output variables, e.g. voltage, frequency and efficiency, depend on the angular speed of the generator. Most electric generators have greatest efficiency at large rotational frequency, commonly ~1500 rpm
      - Deflection of the fluid constitutes a change in momentum of the fluid
      - Pelton Wheel
- System efficiency
  - The hydraulic ram pump
    - well established for domestic and farm water pumping at remote sites, where there is a steady flow of water at a low level.
    - The kinetic energy is obtained by a mass of water M falling through a head H, and out through the impulse valve V 1
    - The potential energy MgH of the supply water is first converted into kinetic energy and subsequently into potential energy, mgh.
  - Social and Environmental Aspects
    - Mature Technology
    - It produces about 20% of the world’s electric power.
    - long-lasting with relatively low maintenance requirements
    - the flow can be controlled to produce either base-load or rapidly peaking power as demanded
    - mitigates emissions of the greenhouse gas CO2
CHAPTER 4 WIND ENERGY
- Power extraction by a turbine
  - The fraction of power extracted from the wind by a turbine is by the power coefficient Cp. At any instant, Cp is most dependent on the tip-speed ratio , unless the machine is controlled for other reasons
- Characteristic of the wind.
  - Wind Speed Patterns
  - Wind Shear Profile
  - Micro-meteorological Range: Turbulence
  - Wind Speed Distribution: The Macrometeorological Range
  - Long-term Fluctuations
  - Distribution of Wind Direction
- Type and terms
  - Concentrators
    - Turbines draw power from the intercepted wind, and it may be advantageous to funnel or concentrate wind into the turbine from outside the rotor section
  - Vertical-axis Machine
    - Evans rotor
    - Musgrove rotor
    - Cup anemometer
    - Savonius rotor (turbo machine).
    - Darrieus rotor
  - Horizontal-axis Machine
    - Upwind and downwind machines of rotor diameter more than about 10 m use electric motors to control yaw
    - The three-bladed rotors operate more ’ smoothly’ and, generally, more quietly
    - Single-bladed rotors produced too many difficulties for commercial prospects
    - Multi-blade rotors, having large starting torque in light winds, are used for water pumping and other low frequency mechanical power
- Linear momentum and basic theory
  - A complete physical representation of this actuator disk
- Wind Power
- Electric Generation
  - Class A: wind turbine capacity dominant, PT >> PG
  - Class B: wind turbine capacity  other generator capacity, PT  PG
  - Class C: grid linked, wind turbine embedded in a large system, PT  0.2 PG
- Mechanical Power
  - Heat production
  - Water pumping
  - Grain milling
  - Sea transport