The following question was recently posted on Quora:
“Why are wind farms put so close to rural towns and people?”
Energy expert Mike Barnard offered the following response:
In general, it’s easier to put up a wind farm nearer rural communities rather than further for five reasons:
- Grid connectivity
- Access roads
- Workforces
- Finding leaseholders
- Local power consumption
The combination will tend to make it easier, faster and cheaper from many perspectives to construct a wind farm nearer a rural community than further from one. Let’s have a look at them.
Grid Connectivity
Wind farms generate electricity. That electricity has to be put into the grid in order to get to the people and businesses who need it. However, all wires are not the same.
There are usually four levels of most grids. The first are the wires to homes and businesses. These are running at the voltage which consumers need in their wall sockets, 110, 120, 220 or 230 volts most commonly. The second are the local lines which lead to small transformers near homes and businesses. Those wires run at -- usually -- somewhere in the range of 25,000 volts, and the transformers step the voltage down to the consumable range. In turn, there are local major transformer centres where the 25,000 volt lines converge and larger distribution lines running around 100,000 volts feed in. Finally, there are the major transmission lines at 250,000 volts running from major generation plants to the transformers that step the voltage down to the 100,000 volt level. This varies around the world, but it’s a fairly common pattern.
The reason for the variance is that the higher the voltage, the further that the electricity can be transmitted with lower losses. Balancing the various gauges of wire and transformation steps is a fundamental job of grid management requiring planning, infrastructure deployment, maintenance and management.
Utility-scale wind generation typically generates more than the demand of a local network of 25,000 volt lines requires, so wind farms usually plug into either the 100,000 volt or 250,000 volt lines. Wind farms haven’t in the past had the luxury of demanding 250,000 volt transmission lines in the locations with the best wind resources. As a result, a very large number of smaller wind farms around the world have typically been plugged into the 100,000 volt lines.
Those lines and the transformer stations which serve them are typically most accessible near rural population centres. In general, it’s easier and cheaper to put wind farms where they can plug into that level of line than not, and every kilometre additional distance adds costs. This tends to nudge wind farms closer to rural towns and villages.
Access Roads
During construction and major maintenance efforts, large trucks need to easily get to the wind turbines. This requires pavement to close to the wind farm and well built access tracks to the wind turbines themselves.
Just as with electrical distribution, roads and other transportation infrastructure are much denser and more robust near population centres than further from them. If you have to build an entire 10 kilometre road to a distance wind farm, then all of the access tracks, this costs a lot of money. If you build a wind farm around a farming community, most of the road infrastructure is already in place and you just have to build or improve short access tracks to the bases, something farmers usually consider as an improvement to their properties.
The economics of physical access to a site tends to nudge wind farms closer to rural communities.
Workforces
During construction, wind farms have a bunch of expert crews who live locally for a few months or a couple of years who need accommodation, food and entertainment. And they need a bunch of locals for more general skilled trades, site security, road building and the like.
It’s much easier to find accommodations and food as well as additional local resources where people live in communities rather than further away.
Finding Leaseholders
Most wind farms aren’t built on purchased property for the simple reason that wind farms only need 1% to 2% of a given land area for the turbines, access roads, transformers and any other infrastructure. They instead provide lease payments to the land owners based on a variety of factors. When people are prospecting a wind farm site, one of the key activities is to lock up agreements with the people who own the land.
How do you find those people? Well, it’s a lot easier when they are gathered in a community with a county office with land ownership information and places where you can meet the owners. It’s a lot easier in places where you can put up a booth or a tent at a gathering and attract a bunch of interested locals. Those are called rural communities. When your wind farm might spread over 50 properties and 20 square kilometres, having a central hub to meet most of the property owners is much easier than striking out into the wilderness, finding a tract of suitable land, getting its GPS coordinates, then trying to figure out who might own it.
Just getting leaseholders for a turbine or three each is much easier where there are communities, which tends to nudge wind farms closer to rural towns and villages.
Local power consumption
In the first point about the different voltages, the point was made that utility scale wind farms typically generate more electricity than is required by a local 25,000 volt grid. While developed countries average only 7% loss of electricity in the grid between generation and consumer, the closer the generation is to the consumer the lower the losses.
Putting up a wind farm near a community means that a bunch of the electricity it generates will be consumed locally instead of being transmitted greater distances a large part of the time. This lowers overall transmission losses and increases the overall efficiency of the electrical grid. This is worth real money as utilities which sell to consumers are the ones typically liable for the 7% loss in generation, applying a number of fiscal, contractual and technical approaches to minimizing those costs to them. Putting greater grid feed interconnections costs money, but it costs them less money near rural communities and it provides them additional local consumption benefits.
Efficiencies from consuming some of the power from the wind farm in a local community will tend to nudge wind farms closer as well.
Balancing Factors
In the developed world, this economically and environmentally nudging of wind farms closer to people is balanced by reasonable protection from unwanted environmental noise. Most countries have setbacks based on minimum distance, maximum noise standards or both. These are put in place to protect the people the wind farms are near and are strongly evidence based. Typically, the science of acoustics, the medical concerns related to excess environmental noise disturbing sleep and the culture of a region balance out to wind turbines being 400 to 600 meters at closest to people’s bedrooms.
Also, towns themselves have much rougher and taller obstructions -- buildings -- to the wind than the ridge lines and flat farm land near town and are typically built in more rather than less sheltered areas such as the bottom of valleys as opposed to the tops of hills.
These two combine to nudge wind farms a little further from the centre of populations than they would be otherwise. And of course they also explain why no one is building major wind farms in larger cities.
And of course areas with very significant wind resources, Class 1 winds which are strong and constant, are worth putting huge wind farms in, tying them into 250,000 volt long-distance transmission lines and shipping the electricity to the major population centres without going anywhere near the local consumers. Offshore, northern Brazil and US prairies wind farms fit this model, and more long distance transmission is being put in place to accommodate growth of wind farms in those regions. But long distance transmission is expensive to build and has its own detractors and campaigners to overcome.
Summary
Wind energy at utility-scales tends to appear nearer rural towns and villages rather than further from them because of the obvious factors outlined above. Finding the people who will do many of the non-expert roles during construction and provide ongoing maintenance is easier, finding the people who own the land is easier, plugging into the grid is easier, getting to and from the sites is easier and in general it’s more efficient to have local consumers for at least some of the electricity. It’s pretty obvious why wind farms have tended to be nearer rather than further from people.
Updates to this material can be found here: Why are wind turbines put so close to people?