Using geography in site analysis
Siting a wind turbine
In this example we are going to look at the scenario of a Utility company looking to place a wind turbine on land that they already own and how desktop geographic analysis can be used to whittle down the number of potential sites and therefore the number of site visits which reduce the cost of finding the right site.
So let's start with a regional overview of the midlands of England and then start to add in a series of constraints that will restrict where a wind turbine can be sited...
The first of these is to look at the locations of areas of land that cannot be considered, in this case Sites of Special Scientific Interest (SSSI), national nature reserves, National Parks and Areas of Outstanding Natural Beauty (AONB).
Next there are aviation restrictions whereby wind farms cannot be within 30km of an airport, in this case the civil aviation airports.
However in this part of Britain there are a number of Military airfields which also need to have a 30km buffer placed around them
When combined these buffers cover a significant part of the region we are looking at.
There is also the need to have a decent amount of wind in the area so that a potential wind turbine will give enough output and this map shows windspeed data across the region.
When combined with the other regional restrictions there are not many places that can be considered for further investigation...
... basically the coastal region of the Essex, Suffolk border highlighted in the blue circle.
Looking at the area of interest in more detail we can see the natural and aviation restrictions and can then consider other factors in our assessment of a potential site.
These include needing to be away from mast sites.
As the planned wind turbine needs to be on existing water company real estate we can then look at where the pumping stations are in the area that could be used for this purpose.
We can then combine these again with the windspeeds in the area...
...to give us a more focused area to look at, highlighted in the red circle
So far the assessment has focused our attention on an area to the north of Ipswich
There are 8 pumping stations in this area for us to consider as a potential site.
However at this level of detail there are further restrictions to consider, most of these revolve around the effect on local residents so it is important to know where people live. Here we have overlaid addresses in the area.
These restrictions include needing to have a 500m noise buffer around a turbine. The addresses within these buffers are highlighted in red.
Most of the pumping stations have several addresses within 500m of them, in particular the ones toward the centre of the image. Two that are possible are highlighted yellow, in the northwest and in the centre of the south of the area shown here.
A further consideration is that of low level flicker from the moving shadows of the rotating blades caused by the sun at low levels around sunrise and sunset. In both cases there are some addresses in this zone however they are towards the edges of these buffers so may be ok.
At a very practical level there is the need to consider how the equipment will be transported to the site. In these cases the northern of the two sites is very close to a B road connecting to a primary dual carriageway road. The southern site is some way from major road infrastructure and is only reached by minor lanes.
It is also worth noting that for the southern site an Electricity Transmission Line running NE-SW passes very close to the site, which pretty much rules this site out.
Taking these restrictions into consideration there is now only one viable site which can be easily reached by the large vehicles that will need to access it bringing the parts from the nearest sea port at Harwich.
Looking in more detail at the most viable site in the area, we can now consider the restrictions which only apply at this level.
Firstly what water is near by that could be contaminated either during building or afterwards? There is a river and ponds, so care would need to be taken during construction
Is the site at risk of flood, in this case the Risk of Flooding from Rivers and Sea data comes close, but do not reach as far as the chosen site so the site should be ok, although flood mitigation measures around the electricity units on the ground might be prudent.
Again at the local level there are also restriction buffers to consider, in this case needing to be 100m from a road...
...100m from railway lines...
...and 100m from public rights of way. In all three cases the potential site is outside these buffers.
We can consider further restrictions and also revisit ones looked at earlier but here in more detail.
This is an elliptical obstruction buffer and, apart from the pumping station itself, there are no features of concern here.
The 500m noise buffer we saw earlier does not contain any addresses so there is no concern here.
The 800m flicker shadow buffer does contain addresses however there is also vegetation and topography to consider which may block these...
...as well as the lay of the land, such as the dual carriageway being on an embankment which would block part of the view from the houses to the north east of the site.
This leads into an assessment of the visibility of the turbine in the area. Zooming out this can be seen as green over the height data for the area and as this shows the visibility is quite restricted, which is good from the perspective of the turbine being considered a 'blot on the landscape'.
Finally a visual of what it might look like can be created. The advantage of all of this is the ability to assess a site or any number of sites without leaving the desk and then only sending staff out in to the field once the choices have been whittled down. The use of geographic intelligence here has enabled better decision making at a lower cost.
Further detail about these can be found on the OS website product pages
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More story map examples like this one can be found on the More Than Maps site.
