Towards better long-term energy security

04:13, Aug 31 2012
Carolyn Hughes
SWITCHED ON: Carolyn Hughes advocates greater efficiency of power usage

How secure is the top of the south's power supply? This was the theme of a recent conference organised by Nelson Environment Centre and Meridian Energy.

It can be an emotive question as few of us can imagine life without power. So it is understandable that many think of electricity as an essential good, a human right like water, food and shelter and assume that its continuous supply is guaranteed.

It isn't. Our power supply is not 100 per cent secure for several reasons.

The backbone of the South Island's power supply comes from the Southern Lakes and relies heavily on plentiful rainfall. In a dry year, usually every third to fourth year, the South Island cannot generate enough hydro power to meet demand and so draws thermal power from the North Island. During a wet year the Southern Lakes region supplies cheap power to the North Island.

As the top of the south is generation-poor, we import 120 megawatts, 80 per cent of our power needs, via the single 220kV Southern Lakes transmission line which travels through remote country and across several faultlines - the Wairau, Awatere, Clarence and Hope faults. The biggest threats to security along this line are earthquake, landslide and extreme weather events. The next biggest threat is a single point failure from earthquake, flood or fire at the Stoke Substation.

Affordability also affects the security of our power supply. Demand for power is growing in our region at 1.9 per cent a year, pushing prices up, as does investment by Transpower, the national grid operator, to upgrade the ageing grid.


Growing demand also puts pressure on generators to build new power plants which are becoming more expensive to get off the ground. We have all noticed our electricity bills going up. These increasing prices are hitting households hardest because, unlike big users, we cannot negotiate lower prices by buying electricity in bulk on the wholesale market.

A large portion of New Zealand's housing stock is substandard and poorly insulated so that heating consumes a big chunk of the household budget. Households which spend more than 10 per cent of their income on keeping warm are considered to be in fuel poverty. In 2011 over 30,000 households in New Zealand had their electricity cut off because they couldn't afford to pay the bill.

How can we improve the security of our power supply? We can reduce overall demand for electricity by using less of it and by using it more efficiently. If demand is significantly reduced, investment in large, centralised utilities will not be needed.

We can make our supply more flexible by having a diversity of power sources. No one form of generation is 100 per cent reliable. Hydro needs plenty of rain, wind turbines like a steady breeze, photovoltaic cells rely on the sun shining and thermal depends on limited resources of coal and gas and can go offline through faults or natural disasters.

Overall, diversity of generation improves electricity supply as it creates choices for managing it. When there is a problem with one source of generation then we can switch to another.

Making local contingency plans so the community can respond and adapt to a power outage is also more effective than building centralised utilities.

Civil Defence and local lines companies can work with the community on local distributed generation and "make it through" initiatives for homes and businesses.

We can become more resilient to power outages. Remember that 100 years ago nobody had electricity. Why not learn how they managed without it. Just make sure you have a solar-powered battery for your iPad.

Carolyn Hughes is the manager, clean energy, at Nelson Environment Centre.