Andrew is the Senior Engineer in the Development Division of Transpower. His address was highly topical following the recent electric blackout in NZ, although hardly reassuring. Transpower is responsible for the nation-wide distribution of electricity, from the generators to the retailers. It has three divisions, System Operations, Grid Delivery and Development. His role is to plan twenty years ahead and to be "as little wrong as possible". His personal speciality is in transformers and power cables.
He explained how the consumer's cost of electricity comprises one third basic electricity, one third transport to the retailers and one third retailers' costs and profits. The National Grid is composed of 11,000 km of wire, comprising 80 million metres of wire in the sky. Distribution has to occur in real time as no effective storage system exists as yet. Input has to match delivery at 50 megahertz, and if the gap varied beyond 5 megahertz either way the whole system could collapse and take 36 hours to "re-boot".
He explained how our production is based on 78% renewables, but some of these, such as wind farms and solar panels, are inconsistent in the short term while hydropower can be inconsistent over longer periods, as in a drought. Therefore, there has to be some over-capacity and some ability to access extra power. Currently the coal burning Huntly Power Station copes with the extra loads, but a generator can take 12 hours notice to start up.
The future is uncertain. It can take up to 20 years to design, consent and build a power station, and 12 months for a wind farm. Solar panels are becoming cheaper as are batteries but at present both are expensive. With the future of Tiwai Point (which consumes 13% of our total production but is in an inconvenient location) itself uncertain, no power company is likely to risk major long-term expenditure on a new power station. As the price for electricity paid to the generators is based on an auction system it is in their interest to keep the supply of electricity as "just enough but not too much" to maintain high prices and profits. It is indeed a powerful and electrifying dilemma.
Overall, we now understand much more of how our electricity system works and we are grateful to Andrew for a most interesting and topical address.
If you would like more information consult www.transpower.nz
