Wind, wave and tidal power - lecture 8 Flashcards
Wind and marine energy in the UK (DECC, 2011) UK renewable energy road map- renewable energy review
- onshore wind- capacity in 2010 (GW)= 4 , projected capacity in 2020 (GW) = 13
- offshore wind- capacity in 2010 (GW)= 1.3, projected capacity in 2020 (GW) =18
- wave capacity in 2010 (GW)= 0.002 projected capacity in 2020 (GW) =0.15
- tidal capacity in 2010 (GW)=0 projected capacity in 2020 (GW) =0
- tidal stream capacity in 2010 (GW)=0.002 projected capacity in 2020 (GW) = 0.15
technical resource = amount we think we could technically exploit using current technology. For example, offshore wind has a high potential with 400 TWh/yr
- big difference between wind and how solar will be exploited.
- what actually happened, 2016 data onshore has currently just under 10GW & offshore grown just over 5GW and if you add wave (tidal range capacity) + tidal stream together its capacity is less than 0.01 GW so seen a decline in sector.
- UK 50% of tidal range capacity across Europe but not exploited eg. due to cost
Projected levelised cost ranges for electricity technologies in 2020
- off shore wind reasonably competitive but once we get to marine technology, they become much more expensive.
- one technology that can compete with combined cycle glass turbine (CCGT) is onshore wind
- look at diagram
Case study: Scottish and Southern Energy’s Clyde windfarm
- South Lankarkshire
- 350 MW windfarm
- Europe’s biggest single contested onshore windfarm will compromise 152 windturbines
- provide enough power for 270,000 homes
- investment of £500 million
- more than 200 construction jobs provided
- 30 running staff are employed
- largest capacity of onshore wind, in 2015 wind turbines generated just under 12% of UK’s electricity, so fastest expanding and renewable technology.
- economics is one reason for this
Why wind power has become so widespread& invested in:
1) economically competitive
2) wind turbines are a scalable technology so can be delivered at different scales so can be used for properties (local levels) or can be connected to the grid.
- so barriers of investment comes down, can fit to particular places and can’t fit inline with investment
- easy to maintain
3) low-carbon - LCA between factor of 40-80 scaling in terms of carbon that goes into production, saving you, get over lifetime between 40-80
4) know technology been around for a long period of time.
valley and mountain breezes
land heats& cools more rapidly so land is warmer than sea during the day, warming effect, heat rises get circulation, onshore breeze and opposite happens at night time and you get mountain systems whereas air warms up early in day, start to get warm air thermals rising , cold air deposited into the valley bottoms and opposite effect as mountain cool in the evening, then get cold air dropping down into valley bottoms along the sides.
- all systems mean wind energy as a resource looks different in different places
- get much more assurity in a coastal location, hence the drive for offshore rather than lowland onshore locations.
Map for onshore wind ( Boyle, 2004)
- UK is well situated for wind density
- particularly the North is high but there is a variation in wind density - much higher winds at sea coast > out to open sea and on the top of hills and ridges than you would have in sheltered terrain.
- so onshore wind farms have to be in exposed places , so areas of high terrain are best but visibility issues + problems of landscape impacts.
Wind farms
- used for a long time- old technology
- have horizontal access turbine (access horizontal and turbine spinning around it).
- propellers spin, intercept power and convert motion of propellers into electricity.
- 120m on land
- also have vertical access turbines called ‘darrieus’ turbines after the inventor- they are more closed,more turbines you get, more wind you can intercept as its hitting more of the blades of the turbine.
- ‘darrieus’ turbines spin om the vertical access to drive turbine.
- Restricted as cab only go up to certain size, if it can be scaled up = high demand for offshore environments where high windbut potential for stress of propellers
Power of the wind
P= 0.5 . P. A . V3
- look at powerpoint
Power you get from turbines
- look at diagram
- all wind turbines have a ‘cut- in speed’ only start generating at a certain point eg. turbines are idyll on slightly less windy days
- rapid increase in the amount of power you can drive into a turbine as wind speed pics up
- turbines are designed to be less efficient at high wind speeds to prevent damage from storms.
Power you get from turbines
- look at diagram
- all wind turbines have a ‘cut- in speed’ only start generating at a certain point eg. turbines are stagnant on less wind days
- rapid increase in amount of power you can drive into turbine as wind speed picks up
- turbines are designed to be less efficient at high wind speeds to prevent damage from storms.
Environmental impacts of wind turbines
- noise pollution - despite technology improving for a home that is 300m away from turbine, the noise is about 40 decibels (fairly busy road in city you can expect around 60).
- visual impact in urban locations
- birds flying into them
concerns about sensitivity to vibrations - lewis case study - land drainage & ecosystem change set up in peatland areas so many systems drainage impacts ecology
- electro magnetic interference if you have them near a TV or radar can have impacts, reflects off turbines so interfering signals
- radar is a big concern for military
Bird fatalities
- look at tables
- issue around birds focuses on highly protected species so Lewis example, local population of golden eagles
- bird strike ( fairly rare) - study in Denmark, set up turbines offshore within migratory patterns of birds to access bird strike and found it wasn’t a major concern.
- the birds tended to avoid the turbines
- there are some turbines that have systems to detect large flocks of birds so can turn off turbines and protect bird species.
Position on wind power in IEA Wind Member countries 2012
- look at table
- for large systems, wind power is making sizeable contributions
- China & USA have massive energy demands, 5% coming from wind
- In Denmark at extremes its 40%
- Ireland get 24% from wind
- Portugal gets 22% - several countries getting around 20% from wind
- good choice as we try to de-carbonise
La Rance tidal power plant
- In France
- 240 mw
- installed late 60’s early 70’s
- harvesting variability in water heights between low and high tides
- barrage, sites across estuary, water gets trapped, release it and drive turbines.
Spring Tides and Neap Tides- look at diagram
- primarily driven not by sun (does contribute) but by the moon and gravitational pull/ force of moon
- so when moon is sitting next to earth, it will have a gravitational pull that distorts the surface of the water and causes a high tide.
- can look at juxtaposition of sun& moon and identify that when they are acting together as sun also has a gravitational force, when they’re inline with eachother, get a spring tide (particularly high tide).
- when they’re set against eachother at 90oc get a neap tide (low tide) & cycle of tide goes through every 14 days get a spring tide or a neap tide in line of passage of moon.
