Bryan Leyland: Wind farms not everything they're cranked up to be

Windpower is not necessarily the anti-climate change weapon that many, from politicians to lay people, mistakenly believe it is. Photo / Supplied

Virtually all the main electricity generators in New Zealand have wind farms in operation, under construction or going through the Resource Management Act approvals process.

The primary driver seems to be that we need more renewable energy to "fight climate change" and that wind power is a very good way of doing this. It isn't.

The fundamental problem with wind power is that it is intermittent and unpredictable. This means that the system operator must take a pessimistic view and assume that no wind power will be available over critical periods.

In other words, he has to make sure that there are sufficient conventional power stations available to meet peak demands. It is often claimed that New Zealand has ample hydropower that can easily back up wind. While this tends to be true during a normal rainfall year, it is most definitely not true during a dry year. Dry years, not normal years, dictate the need for new power stations.

The wind blows least during the autumn-early winter period when the lakes are low and at a maximum in the springtime when the snow is melting and, usually, it is raining. So windpower generates most when it isn't needed and least when it is most needed. As a result its contribution is less than it would be if the wind blew hardest in the autumn.

Windpower is expensive. According to my calculations, its true cost is between 11c and 17c/kWh. This is between 50 per cent and 100 per cent more expensive than conventional power. As an expert witness in the wind farm debate, I have put forward my evidence and my calculations on a number of occasions. No one has refuted them.

Windpower is a totally ineffective way of "fighting climate change". Firstly, it is widely accepted that a 20 per cent contribution by wind is about as much as our system can accept without running into excessive costs and serious problems with system operation.

So even if it were a good idea, there is a definite limit to what can be achieved.

This leads us to a paradox: if wind power is so bad, why are generators still pursuing wind farms with great enthusiasm? I believe there are a number of reasons.

First, and in spite of the evidence, the Government and many people believe that wind power can make a substantial contribution to generating capacity and to mitigating "climate change".

So, for a generator there are a lot of "greenie points" to be won by securing rights to wind resources.

Secondly, there is quite a large difference between the wind resources in one place compared with another. Places with high, steady winds will always be better and are in short supply. So get in quick!

Thirdly, having secured a resource, they have created an asset which they can place on their books and make it appear that the money expended in getting a resource consent is a real investment.

All these reasons apply whether or not there is an expectation that the farm will be built in the near - or even the distant - future. So, from the point of view of the generators, there is virtually no downside in securing a resource.

From the point of view of the people who will be affected by the wind farm, the downside is very large. All over New Zealand groups of local residents have spent millions of dollars of opposing wind farms in their area. This imposes a lot of stress on the people involved and represents an enormous waste of time and effort.

Yet, in most cases, there is no real intention of building the wind farm within the next five years - if at all.

From the point of view of the country, the situation is also quite serious. The long list of wind farms with approvals or going through the process leads people to believe that there is no problem with the security of supply. Nothing could be further from the truth.

Bryan Leyland is a power industry consultant.