Surplus water spilling from the Benmore Dam in the Waitaki Valley. The Lake Onslow scheme would store water to generate power when demand was high instead of relying on fossil fuel. Photo / File
Surplus water spilling from the Benmore Dam in the Waitaki Valley. The Lake Onslow scheme would store water to generate power when demand was high instead of relying on fossil fuel. Photo / File
LIFE AND POLITICS
One of the great things about writing a column is having to get up to speed with a current issue so that you can sound passably knowledgeable.
And so it is with pumped hydro storage, of which I knew next to nothing prior to the Government announcing funding for areport into the viability of Lake Onslow for such a project.
Basically, pumped hydro storage acts like a giant battery. The storage is achieved by pumping water uphill when electricity supply from renewable sources is high and demand low.
At these times - because electricity generation in New Zealand is driven by market forces - the cost of electricity is lower than at peak times (mornings and evenings).
Pump uphill when electricity is comparatively cheap, let it out through the turbines to generate electricity when the demand is high. As far as technology goes, the principle is quite simple.
The scale of what's being considered, however, is massive.
Tussock stretching to the water's edge at Lake Onslow, central Otago. Photo / Fish & Game NZ
It would be by far the biggest pumped hydro storage dam in the world. The surface area of Lake Onslow would be expanded from 8 to 45sq km.
On completion, the lake would be able to store 5000 gigawatt-hours of potential electricity. Equivalent to all the existing hydro dams combined.
Though it wouldn't add much to overall electricity capacity, because it would use so much electricity itself pumping water. The value lies in storing electricity potential and making it available when most needed. Thus helping to overcome one of the limitations of renewable electricity sources, which is that the power generated isn't always available when you want it.
The fossil-fuel-burning Huntly Power Station fills the gap when electricity demand is high. Photo / File
The sun isn't shining from 5 to 8pm in the middle of winter when electricity demand is high.
The other problem that the scheme would help alleviate are the times when our existing hydro lakes run dry due to low rainfall. This has historically meant firing-up the fossil-fuel-burning Huntly Power Station to meet demand.
There are other sites around the country possibly suitable for pumped hydro storage, even in Northland, but not of this size and with the natural geological features that would reduce costs.
Greater energy efficiency would also result from economies of scale. This is one of those instances where going big might be best.
Given how the electricity market works, there's currently no incentive for companies to store electricity. Only a government-owned mega-battery at Lake Onslow would deliver the security of electricity supply to back-up all the solar and wind initiatives being pursued around the country.
The "Onslow battery" would likely lead to downward pressure on electricity prices. Good for household power bills.
Though we have to consider another hefty item of Government expenditure (possibly $4 billion) that will need to be paid for through taxation.
There's much more to find out. Which the report will presumably go some way to helping us understand.
Whatever the merits of the Lake Onslow battery, and it's decades from ever being built, there still needs to be a broader debate about New Zealand's energy use.
In 2050, will we be generating electricity to maintain a two-car per household lifestyle, just that they'll be electric now rather than petrol-powered?
Or are we envisaging a future where electricity is used to run a large national fleet of electric buses and a greatly expanded electric rail network? With the number of private vehicles on the road declining over time?
The latter option will use far less energy than the former.
One of the problems with a lot of thinking about energy within government circles is that it's focused on enabling current lifestyles, especially middle-class and wealthy ones, to continue.
That's not realistic or particularly just to those who don't enjoy such lifestyles and are instead struggling to pay each week's power bill.
The best way to lower our electricity bills is for some of us to use a lot less of it. If my market economics is correct, surplus supply over demand means a lower price.
The worry is that in the future the converse is true, demand is high and supply limited. This will hurt poorest New Zealanders.
If the Lake Onslow scheme is to go ahead, it must be part of a strategy of making energy fairly accessible to all of us for our basic needs.
• Northern Advocate columnist Vaughan Gunson writes about life and politics.
