04. Renewable Energy 1

• Energy sources that are naturally replenished and can be used without the risk of depletion

• OR: Energy derived from natural resources that generate over short periods and do not deplete with use

• Because of minimal environmental impact —> Synonyms: Clean Energy, Sustainable Energy or Green Energy

• Environmental - Emission reduction

• Sustainability - Naturally replenished

• Energy independence - Less dependency on international energy market and price fluctuation

• Jobs and economy - Increment in jobs for manufacturing, installing, maintenance

• Health - Declining usage of fossil fuels

• … and more

• Silicon-based PV first technology enered the market

• There are four generations of PV cells

• Working:

• Cell types

  • Organic materials OSC PV cells

  • Perovskites PSC

  • Quantum dots (QD)

  • …

• Poor market penetration

• Nano PV or hybrid inorganic cells (low costs and flexility)

• Organic PV (OPV) (less harmfull to the environment)

• Solar Absorber Materials (could lead to higher efficiencies)

PV System include: Solar Array, Inverter, Battery, Cabling,…

• Stand-alone PV system (with/without battery)

• Hybrid PV system (with wind tubine, hydro turbine, diesel generator, fuel cell, …)

• Grid-connected PV system (bimodal system with battery or directly connected to utility without battery)

• On- or off-grid

• Road-integrated

• Agri-PV

• Vehicle- or building-integrated

• Floating

• ….

• Tilt angle (PV energy output)

• Orientation (maximizing absoption of sunlight and energy production)

• Solar radiation (output current of PV cell)

• Temperature (increasing, decreasing efficiency PV)

• Humidity (efficiency of the solar cells, thin layer of water)

• Wind speed (improve operational efficiency of modules by decreasing temp. of the cells)

• Shading (consumes energy, don’t produce)

• Dust (blocks radiation)

• Uses mirrors to focus direct solar radiation on a fluid-filled receiver

• Heat transfer fluid (HTF) conducts heat —> use for steam turbine to produce electricity

• Types: Linear focus and point focus (higher temp.)

• Linear focus: Parabolic trough, Linear fresnel reflector

• Point focus: Parabolic dish, central receiver

• Unglazed Solar Collectors (heating)

• Transpired Solar Air Collectors (heating)

• Flate-Plate Solar Collectors (cooling)

• Evacuated Tube Solar Collectors (cooling)

1. Horizontal axis

   • Lift rotors: Propeller rotors

   • Drag rotors: Windmills, mulit-wing rotor

2. Vertical axis —> Fixed pitch rotor blade, gear box, generator

   • Lift rotors: Darrieurs rotors

   • Drag rotors: Savonius rotor, wind cup

Towers

• Mostly turbular

• Out of steel, painted light grey

Blades

• Out of glass-fibre-reinforced polyester or wood-epoxy

• Matt finishing —> reduce reflected light

• Simple words: Reverse action of a fan

  • Fan’s electricity is used to turn rotor and blades —> produces wind

  • Energy from the wind by making use of the force the wind exerts on exposed planar surfaces

• Turbine blades designed for moving, in response to the wind —> extracting energy and power available

• Rotor faces into the wind —> achieved by steering by the yaw motor

• Wind passes over the rotor blades causing the rotor to turn

• Gear box to increase roto’s revolutions per minute (RPM) —> otherwise no generated electricity for slow wind speeds

• RPM increases —> generator sends and electric current to the control box

• Current is used as DC or converted into AC

Tower

• Must carry the nacelle and rotor blades, absorbing huge static loads —> cause: varying power of wind

• Made of concrete or steel

Foundation

• Foundation for stability

Rotor

• With help of rotor blades converts energy into rotary mechanical movement

Blades

• Made of glass-fibre or carbon-fibre reinforced plastics

• Blade profile similar to an airoplan wing, same principle of lift

• These forces cause rotation of the rotor

Nacell

• Holds all turbine machinery

• Connected to the tower via bearing for follow the wind direction

Gearbox

• Converts rotor motion which is required from the generator

• Task: Matching rotation speed (slow) of rotor and generator (fast), several steps to cover for various wind conditions

Yaw Drive

• Ensure maximal amount of electric energy —> keep rotor facing into varying wind direction