Pump hydro vs other renewable options

A109 Light Utility Helicopter flight with mayor Gisborne City from the air in November 2023.

Opinion

At a time when most of the world is in the grip of an energy crisis, we here in New Zealand need to take advantage of our position amongst the few who have more time to transition fully to renewable energy sources.

In the process of making those important decisions, we should be able to avoid the mistakes of other countries that have been panicked into precipitate action, even turning a crisis into a national emergency that some governments will not survive.

So, first of all, let us examine the reasons for this latest energy crisis — not all of which are related to the war in Ukraine and the associated fallout when Russian gas stopped supporting the European economies and domestic demand.

Some, including Australia and the United States, are suffering as much as anything from self-inflicted wounds — ie, decisions to reduce emissions within a time frame that was ideologically driven but has necessitated the premature closure of coal-fired power stations before alternative energy producing plants are either built or commissioned.

It will be a test of the respective voting public’s commitment to these volatile political strategies as to whether the governing parties in those countries remain in power long enough to see the transition completed.

Fortunately, we here in Godzone are in a position where we can remain committed to our emissions reduction targets without having to face the threat of blackouts at a time when any replacement power stations are still in the pipeline.

But we do need to make good use of that precious time in order that the choices we make about our future mix of clean energy supply are the ones most suited to the economy we operate, and not necessarily the ones that would curry favour with our fellow humans on the other side of the word.

Secondly, having established what type of current energy supply needs to be replaced with clean plants, we can identify the alternatives that meet the following criteria:

1) Price of establishing the replacement plant.

Consideration is currently being given to a pump hydro scheme at Lake Onslow in the lower South Island, which is likely to be rejected based on a number of comparative factors.

For one, it is uncompetitive with other options that have a similar capacity to meet baseload energy needs when demand is high and there is a shortfall in other supply. The estimated establishment cost of the Lake Onslow proposal is approx $15 billion, which is almost twice the establishment cost of a medium-sized nuclear plant with the same capacity.

Other factors include:

2) Operational costs of plant.

Pump hydro plants use a huge amount of the energy they produce pumping the water uphill to the lake where it can be reused.

3) Reliability — wind and solar will always have a question mark over them until batteries are large enough to store the energy they produce when the wind blows and the Sun shines.

4) Distance from the end user — particularly important when the bulk of the population resides in the top half of the Nth Island.

5) Environmental considerations related to plant site and disposal of any waste materials.

There is a current environmental lobby which appears opposed to building large new hydro plants anywhere in the country, even though it is debatable whether this would be the best option for provinces like ours where the efficient use of stored water is a critical factor in the choices we should make.

All in all, some interesting choices we have at our disposal.

My concern is and has always been that we look at the choices dispassionately — simply selecting those that are the best fit for a country of our size and philosophical heritage.