John Blakeley: Solution to power needs is blowing in the wind

COMMENT

The Green Party has started a campaign to stop Project Aqua, Meridian Energy's planned $1.2 billion hydro-electric project on the Lower Waitaki River. The Greens say they are not prepared to see one of our major remaining braided rivers turned into a "muddy trickle".

For a number of years, the national electricity demand has increased on average by 2 per cent, which is about an extra 800 gigawatt hours (GWh) a year. Project Aqua will produce 3000 GWh in an average year and 2000 GWh in a very dry year. It will be built over at least six years. Meridian hopes the first power will be produced in 2008, and that the project will completed around 2011.

From the above figures it is clear Project Aqua will provide a little under four years of the country's electricity demand growth in a normal year, so by itself it can only produce about half of the expected increase in demand over the next eight years.

Nevertheless, combined with a number of other smaller electricity generation projects, it should be sufficient to cover our increasing need for power and maintain security of supply. The question that now needs to be addressed is: if as a result of the level of environmental opposition Aqua does not proceed expeditiously, what are the alternatives for maintaining security of supply up to around 2011?

The first and obvious solution is to remove the growth in electricity demand by a combination of more efficient energy use and conservation. It has frequently been said that there is the potential to remove 20 per cent of our consumption in this way but there is little evidence yet to suggest that consumer habits are changing.

Much more encouragement of better insulation of new houses and installing solar water heating in new and existing houses would be a good place to start, as well as much wider use of energy-efficient light bulbs.

There has been some success in encouraging energy efficiency over the past three years, but this has been masked by other factors such as population growth, increasing use of household appliances and industrial growth, to the extent that there is no noticeable difference in the rate of electricity growth compared with previous years.

Furthermore, if the Government's goals for increased economic growth are to be achieved over the next decade, there must be sufficient electricity available.

Hydro power is still the predominant source (65 per cent) of our electricity generation but apart from Project Aqua what other future hydro options are there?

Hydro projects take a number of years to plan, design and gain environmental approvals, so it is unlikely that any other substantial hydro project could even be under construction within the next five years.

For larger hydro projects over 50 megawatts capacity, a great deal of work has been done to investigate potential, but most of these projects have been discounted on technical feasibility, economic or environmental grounds. No larger hydro projects are being considered in the North Island. Further south, the potential seems to be limited to the Upper and Lower Clutha River and Project Aqua, plus perhaps a possibility or two on the West Coast.

The potential for smaller hydro projects is also surprisingly limited at anything like today's electricity price. Possibly the total buildable resource in a considerable number of smaller projects around the country is no more than 500MW, which is less than the capacity of Project Aqua.

There is potential for further geothermal projects to be developed in the North Island, providing environmental approvals can be obtained, but probably only a quite limited amount of increased generation will occur within the next eight years.

As far as new fossil-fuel generation plants are concerned, work is already under way on a new 360MW combined-cycle gas-fired power station at Huntly. This will initially use natural gas previously destined for the much less efficient original Huntly station, which will increasingly have to use coal, with considerably increased greenhouse gas emissions as a result.

With the running down of the Maui gas field, two other new combined-cycle plants at Otahuhu and Stratford, for which environmental approvals were obtained several years ago, have not proceeded because of the uncertainty of future gas supplies. The new Huntly station will use gas from the new Pohokura and then Kupe gas fields once these are developed.

Imported liquefied natural gas has been suggested as another possibility, but is likely to be too expensive to use for electricity generation and would also make the country vulnerable to international price and supply fluctuations.

Further coal-fired power stations could be considered because the country has abundant coal reserves, but proceeding with such projects would be inconsistent with New Zealand's ratification of the Kyoto Protocol because of their high level of greenhouse gas emissions.

We are left with only one other realistic alternative to proceeding with Project Aqua - a very substantial and urgent programme of constructing wind farms. This is already getting under way but continuing strong Government encouragement will be needed.

Because suitable wind conditions for generation can only be relied upon for about 40 per cent of the time, in lieu of the 540MW capacity of Project Aqua there would probably need to be 700 to 800MW of additional wind power capacity constructed.

This could comprise about 10 wind farms around the country, each comparable to the Tararua wind farm currently being expanded near Ashhurst, or the Te Apiti wind farm which is soon to be built near Woodville.

There is an upper limit to wind power capacity beyond which new storage technologies will be needed to keep the electricity grid stable in fluctuating wind conditions. This limit is probably at least 1000MW and could be as high as 1500MW, so is not likely to be a problem for the next decade. In the meantime we can use the storage capacity of our hydro lakes to balance fluctuating wind power generation.

Plan B is, therefore, to construct a number of wind farms over the next eight years, assuming that the required environmental consents can be obtained. Otherwise, if Project Aqua falls over because of mounting environmental opposition and competition for water use, New Zealand's electricity supply is likely to be severely compromised within the next five to seven years by the lack of new generation capacity.

* John Blakeley, the convener of the Sustainable Energy Forum, is a research fellow at Unitec.