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Renewable energy poses problems

There can be little doubt that fossil-fuel based energy sources are something we need to wean ourselves off as soon as possible.

Coal, gas, oil - these energy sources are both dirty, damaging and increasingly expensive. To rely on them for our future energy would be a foolish strategy.

So what do we do instead?

Well there are many forms of renewable energy but unfortunately, they all have their downsides.

One of the biggest problems with most renewable energy is that it can be rather unreliable.

Perhaps the most reliable of all the renewable resources is tidal power - but even that has massive lulls, where tidal turbines will sit virtually motionless as the tidal flows stagnate twice a day.

Then we have hydro-electric. This can be a very reliable source of energy - until it isn't.

All it takes is a period of unexpectedly low rainfall and dam levels can plunge to a point where the turbines can no longer generate the levels of energy required to meet demand. Indeed, this seems to be something that has threatened NZ's power system on an increasingly frequent basis of late.

In some places around the country, wind can be a worthwhile form of "free" energy but with changes in global climate becoming very apparent, predictability becomes just a memory and we're faced with increasing periods of calm or extreme winds. In such extremes, the wind turbines are unable to generate power.

Solar is the other popular energy alternative but it too is unreliable and unfortunately, delivers the maximum levels of energy at the least desirable times. With Kiwis being highly reliant on electricity for heating and cooking, winter evenings represent a period of peak electricity demand but zero solar capacity.

Now you might think that "any renewable energy is good energy" - but I'm not so sure.

The nation's generation and distribution infrastructure has to be designed to cope with the peaks in demand which may be short-lived but are critical. How many would bitch and moan if the lights,heating and TV all went off regularly at 6pm on cold winter's nights because the infrastructure was unable to keep up with demand?

So, regardless of how much "potential" renewable energy we may have hooked up to the grid, we still have to ensure there is sufficient thermal capacity to cope with a situation where the renewables aren't producing.

In a worst-case situation, this could be a cold, calm winter evening after a long dry summer which has sent lake-levels plummeting.

No hydro, no solar, no wind and perhaps tidal flows are at a minimum.

How do we cope then?

The big risk we run with increasing our reliance on intrinsically unreliable renewables is that we greatly increase our exposure to massive shortfalls in generation capacity - when all the renewables are off-line at a time of high demand.

As the price of fossil fuels continues to rise and as we become increasingly reliant on fickle renewable sources, will we also have to learn to live with the fact that power cuts will become increasingly commonplace as supply fails to meet demand?

Or will we all end up paying a huge premium to have many megawatts of fossil-fueled "emergency" generation capacity sitting idle for 99% of the time -- but ready to burst into life when required, to keep the lights burning and the TVs flickering?

Or maybe -- just maybe, we'll all end up with a "power pack" in the garage which contains some kind of chemical (or other) battery capable of storing sufficient energy to make our homes and businesses "self sufficient" during those periods of peak-demand.

Could that energy store be (as has been proposed by others), the EV you use to commute to and from your place of work? Imagine how useful it would be to have half that battery's energy (say 20KW) available to run your house overnight when the tide is out, the lakes are dry and the wind isn't blowing.

Is it time to take a more holistic view of our energy future?

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