Wind and solar are definitely part of a long term renewable energy regime.

However some people are skeptical

Currently the combined production of solar and wind, harvest less than 1% of New Zealand’s total energy consumption.

Expectations are often un-realistic. Everybody should read

They are always only part of the mix due to hourly, daily and seasonal variations in output.

Actual output is 10%-30% of nameplate capacity.

Currently the largest solar farm in NZ is being built at Marsden Point.

New Zealand in not called the land of the long white cloud for nothing!! Even during the daytime if cloudy solar panels produce very little power

Wind and solar will fill the power generation gap! (NOT)

Wind and Solar have taken over 20 years to reach nearly 1% of New Zealand's energy needs (900PJ).

At that rate it will take FOREVER to build enough windturbines to replace the fossil Fuels. As windturbines have a expected life span of 20-30 years, then 3-4% of turbines need replaced every year.

If we had enough windturbines to replace 25% of Fossil Fuel Energy how many would that be?

NZ uses about 550PJ of Fossil Fuel per year, let us assume we need 125PJ of wind produced electricity for that 25%.

The new wind farm going in at Waipipi has 31 windturbines with a total nameplate capacity of 133MW, 455GWh or 1.64PJ output. Personally I would expect them to only produce 300GWh or 1PJ , enough for Auckland’s EV busses .

Even using their optimistic numbers we need 2362 similar windturbines to replace 25% of Fossil Fuel energy.

At the cost of Waipipi this generation capacity will cost $35B

3% of 2362 is 70 turbines need replaced every year. (About $1B per year on replacements)

If Waipipi only produces 1PJ then we need 125 similar wind farms to produce that amount of power, and we need to replace 4 Waipipi wind farms every year. This Waipipi wind farm is costing $277M, the value of electricity produced per year is (at $40 per MWh) is about $18M per year thus will take approx 15 years to return the construction cost.

Converting nameplate capacity into actual annualized generation capacity

In order to find out how much energy the wind turbines produce you have to know the distribution of wind speeds for each turbine. In Denmark's case, the average wind turbines will return 2,300 hours of full load operation per year. To get total energy production you multiply the 1000 MW of installed power with 2,300 hours of operation = 2,300,000 MWh = 2.3 TWh of energy. (Or 2,300,000,000 kWh).

In other areas, like Wales, Scotland, or Western Ireland you are likely to have something like 3,000 hours of full load operation or more. In Germany the figure is closer to 2,000 hours of full load operation.


Solar panels? They cost about $1 per Watt nameplate capacity, actual capacity is approx 10% of nameplate capacity.

So $10 per watt actual capacity through the year.

To provide the 125PJ we need 40GW of installed solar panel nameplate capacity. $40B of panel

So if we install $100B of wind and solar we could reduce our Fossil Fuel demand by 50%

But the ongoing replacement costs will lead to poverty. The EROI is not high enough.