Sustainable Power Systems Flashcards
What is greenhouse effect
Process where heat leaving the earth is partially reflected back onto the earth surface by atmospheric gases
Global warming
excessive concentrations of greenhouse gases cause changes in climate, as more heat is reflected back by the atmosphere
Hierarchy of gases that cause global warming
Water vapour and clouds
CO2
Methane CH4
Nitrous Oxide N2O
Ozone O3
Chlorofluorocarbons CFC
Sources of Energy Supply in Australia ( Highest to lowest)
Petroleum
Coal
Natural gas
Renewable Energy
Nuclear
What is sustainable Energy ?
Energy that can be used without having an overall detrimental effect on the environment
What is MEPs ( Minimum Energy Performance Standards )
MEPS specify the minimum level of energy performance required for various appliances and equipment sold in Australia.
Renewable Energy are sourced from ?
Natural resource that do not become depleted
What happens when batteries are connected in series and parallel
Series = increased voltage
Parallel = increased current
What is the Ah capacity of a battery ?
It is the quantity and duration of current battery can supply.
What is an inverter ?
Is an electronic device that converts a DC current input into an AC current
What is the basic operation of an inverter?
It rapidly switches the dc input in different directions for varying amounts of time. (By using a bridge)
What is Pulse Width Modulation (PWM)?
Is a technique of rapidly switching the current in series of pulses with same magnitude but different duration.
What is the use of a charge controller (battery charger) ?
It enables safe and functional charging, discharging and interconnection with installations.
What is irradiance (G)
The quantity of solar power available at the surface at any instant in time. ( W/m^2)
What is Irradiation (H) ?
The quantity of solar energy available at the surface over a given time period. ( kWh/m^2)
What is extraterrestrial irradiation ?
The quantity of solar energy available at the top of the earth’s atmosphere
What is sunshine hours ?
The average hours of sunshine received at a location over a given period of time.
What is Declination angle ?
angle is the angle between the horizontal plane of the earth (known as the equator) and the horizontal plane of the sun.
What is Equinox ?
- is an astronomical event that occurs twice a year ( March 21 and September 23)
- when the tilt of Earth’s axis is such that the Sun is directly above the equator.
- Day/Night length equal
What is Solstice ?
Is when the declination angle is at its maximum value, occurring twice a year:
The winter solstice is the day of the year with the least hours of sunlight.
The summer solstice is the day of the year with the most hours of sunlight.
What is Radiance ?
Radiance is the quantity of energy emitted from a source :
Direct radiation is solar radiation that comes straight from the sun, casting shadows on a clear day.
Diffuse radiation is indirect sunlight that is scattered from air molecules, dust and water vapour.
What is Reflectance ?
Reflectance is the ratio of reflected radiation to incident radiation arriving at a surface.
What is solar window ?
The area of the sky through which the sun moves throughout each yearly cycle.
What is Latitude
Is a coordinate indicating the north-south position of a point on the earth.
What is Longitude ?
Is a coordinate indicating the east-west position of a point on the earth.
What is Zenith ?
Is a point directly above a location/ an observer.
What is Azimuth angle ?
The angle between the sun and true north in a clockwise direction. Applied to a PV array, a 180 degree azimuth angle indicates that the array faces due south.
What is altitude angle ?
The angle between the horizon and the sun.
What is Tilt angle ?
Is the angle btw the horizontal plane and the plane of a photovoltaic module.
Describe photovoltaic cell.
A cell is a single PV unit, typically producing a nominal output voltage of 0.5 V.
Describe a photovoltaic module
What is a PV string ?
What is a PV array ?
What is the purpose of Bypass diodes in PV array ?
Function of PV blocking diode ?
Allows current to leave shaded strings but prevent current from back feeding into it.
Connected in series with string.
What is are contour maps ?
What is potential energy (E) in MHS
The stored energy that exists due to gravity acting on the water that is held in the forebay/dam.
What is Gross / Static Head (H) ?
List the 5 basic arrangement of a Micro-Hydro System (MHS).
What is flow rate Q ?
The volume of water passing through a point or pipe at a given time, measured in litres per second (L/s) or cubic metres per second (m3/s).
What is Hydraulic Losses ?
Losses caused by turbulence in the water and friction between the water and the walls of the pipework/fittings.
A water velocity of 1 m/s is generally maintained to minimise turbulence. Friction losses are directly proportional to pipe length, so hydraulic losses are expressed in metres (m).
What is equivalent Pipe Length ?
Is the length of straight pipe (of the same size as the fitting) that would cause the same hydraulic loss as the fitting.
Measured in “m”
What is Net/ Dynamic Head (h) ?
The ‘effective’ head, taking the total hydraulic losses into account, measured in metres (m).
Net Head = Gross Head – Hydraulic Losses
What are the 3 primary method of measuring flow rate ?
- Volume and time method
- Area and velocity method
- Notched weir method
What is the volume and time method of calculating flow rate ?
Compare low head and high head system characteristics.
What are impulse turbines ?
Name the following impulse turbines.
What are reaction turbines ?
Name the following reaction turbines.
How does wind move ?
The natural phenomenon we know as ‘wind’ is simply the movement of air. The reason air moves from one place to another is due to a difference in pressure between the two locations – the air moves from the higher pressure location to the lower pressure location until equilibrium is reached.
What is vertical wind speed profile ?
A profile indicating the variation in wind speeds at different heights above the ground.
What is Temperature Inversion Layer ?
A layer of cold dense air in the atmosphere that resists the transfer of wind energy from above to below.
What is the basic arrangement of a wind turbine ?
What is Specific Wind Power (P0)
The available wind power per unit of wind capture area, measured in watts per square metre (W/m2).
What is Cut-in Wind Speed (Vc)
The minimum wind speed required for the WECS to produce useable electrical energy.
What is Rated Wind Speed (vR)
The wind speed required for optimal WECS operation, i.e. to achieve maximum power output.
What is Furling Wind Speed (vF)
The wind speed which causes the turbine to furl or feather (i.e. shut down) to prevent damage.
What is Rated Power (PR) (WECS)
The maximum power output of the WECS. The rated power is achieved at the rated wind speed.
What is Power Co-efficient (cP)
A factor of how efficiently the wind turbine converts the kinetic wind energy into mechanical energy.
What is Output Co-efficient (cO) (WECS)
A factor of how efficiently the WECS converts wind energy into an electrical output.
What is Tip Speed Ratio (λ)
A ratio of the wind speed to the resulting speed of the tip of the turbine blade.
What does Isobar mean on this weather map ?
The isobars indicate levels of atmospheric pressure in hectopascals (hPa), in a similar way that contour lines indicate height above sea level on topographic maps. Winds tend to blow from higher pressure regions to lower pressure regions.
At what positions should WECS be placed uphill and downhill an obstacle ?
What instrument is used for measuring wind speed ?
Anemometer
What are the 2 main types of wind turbines ?
Vertical Axis Wind Turbine (VAWT)
· Horizontal Axis Wind Turbine (HAWT)
What are the names of these vertical wind turbines ?
What are the 2 types of Horizontal Axis Wind Turbines (HAWT)
