Renewable Energy: Wind, Wave and Tide Flashcards
What is Scotland ambition for renewable energy?
How is it going?
A target of 100% renewable electricity generation by 2020.
At present 2015 data says that this will not be met and ‘only’ 87% will be met by renewables. However, there are a number of plants in planning that if built would allow the target to be met. It can be seen that the majority of renewable generation will need to come from Wind Power (onshore and offshore) and Biomass. Hydro plays a rather modest contribution with the old well established hydro plant.
What are the potential renewables?
Solar
- Heating
- Thermal Power
- PV
- Updraft Tower
Tidal
Hydro
Wind
- Offshore
- Onshore
Wave
Geo Thermal
Bio Mass
Why is wind power attractive in the UK?
Because it’s so fucking windy!
The average wind speeds in the hills at 11 m/s with energy densities of 1800 W/m2 and that higher velocities exit at the coast and open sea.
Capacity factor for wind power?
The capacity factor is the annual energy output as a fraction of the maximum possible. In the UK it is about 30%. In European countries it is generally much less.
The typical rated capacity of onshore/offshore in the UK is about?
2 MW onshore
3-4 MW offshore
Windturbine design?
Horizontal
Your average country side wind turbine sold in a store near yooou!
Can’t we just keep on increasing like the windspan?
No?
As the turbine power increase the loadings increase which means that the nacelles get larger and heavier and at some point, different design concepts will need to be considered.
Downside with windpower?
You don’t get that much energy from it which means you need many to produce country size power levels
It’s dependent on the wind which is intermittent -> back up power needs to be available
What is the issue with wave energy?
How to create energy conversion system that can convert that to a useful form.
Significant power levels are believed to be exploitable but would lead to very sizeable devices, eg 5MW would be a 5km device at 50% efficiency.
There have been many devices under development but not many have been developed for commercial use.
How much power can waves generate?
In the UK the northsea has waves of power 70kW/m length of wave front.
Explain some of the forms a wave conversion devices can take
- Passive design
Guide the waves to spill over into elevated reservoirs, which then drain through conventional low-head hydraulic turbines into the sea - Wave motion devices
Induce relative motion between parts of a structure. This motion can then be employed to transfer a working fluid around a circuit, driving a rotary machine in the process - Oscillating water column
The sea water is admitted to a chamber which is vented to the atmosphere. The free surface in the chamber oscillates in response to the waves and induces an oscillating airflow through a turbine and generator.
Which two main methods to harvest tidal energy are there?
- Using a barrage scheme at an estuary to take advantage of the tidal range. Water level changes produce potential energy
- Through fast-flowing streams and conversion of the kinetic energy
Where in the UK is the most obvious place to build a barrage scheme?
Severn estuary, south wales near Bristol 14 m tidal range
What are hindering the tidal energy?
The initial cost. Even though the technology exists but for the amount of GW produce the initial cost is too high compared to other options
Are one in France (60MW) and in South Korea
