Innovation in Action
Innovation is high on the list of TrustPower’s values and you only need to look at TrustPower’s developments in Canterbury to see that innovation in action.
During December 2010 the pumps were turned on at the new Highbank pumping station and water started flowing up the Highbank penstocks, to satisfy the Mid Canterbury farmland’s growing appetite for water.
The development at Highbank is a result of a collaborative partnership between TrustPower, Barrhill Chertsey Irrigation Limited (BCIL) and Electricity Ashburton Limited. The partnership has seen the installation of an intake, fish screening and pumping facilities at the Highbank power station to allow for the delivery of water from the Rakaia River to the Rangitata Diversion Race (RDR), which is on the southern side of the Rakaia River. From the RDR water is then distributed to farmers for irrigation.
Innovative design allowed TrustPower to utilise the existing Highbank penstocks to convey water up to the RDR. This means the penstocks are now used in both directions – to deliver water downhill to the power station for electricity generation and then, in the summer months, to pump water uphill for irrigation.
BCIL chairman John Wright says their shareholders are now reaping the rewards of the infrastructure that has been developed. “TrustPower is an integral part of our success to date and has contributed not only capital but substantial expertise. We simply wouldn’t be where we are today without that.”
This year TrustPower will expand the Highbank pumping station from its current capacity of 4 cubic meters per second (cumecs) to 5 cumecs, and ultimately to 8 cumecs. That will allow the irrigation of 17,800 hectares across 5 linked irrigation schemes, utilising 60km of piped distribution. “There is huge potential to increase the productivity of Mid Canterbury agriculture through irrigation. We expect to continue to work with TrustPower to grow the capacity of our scheme and to improve the reliability of irrigation for our shareholders” says John.
So far TrustPower’s investment has focused on providing the infrastructure to extract Rakaia River water for BCIL. However TrustPower’s ownership of the Lake Coleridge power station provides even more possibilities for innovative development. “Lake Coleridge has a storage capacity of 100 million cubic metres of water. If this storage capacity can be utilised for multi-purpose power generation and irrigation, a further 40 megawatts of generation can be added and up to 80,000 hectares could be provided with reliable irrigation,” says TrustPower's General Manager Commercial Operations Chris O’Hara.
TrustPower has developed a concept which would see a siphon built across the Rakaia River to allow stored water to be released to the river. The water would then be pumped to farmland on both sides of the Rakaia River.
To facilitate the use of the Lake Coleridge storage a modification is required to the Rakaia River Water Conservation Order. TrustPower is currently consulting with key stakeholders under the umbrella of the Canterbury Water Management Strategy with a view to applying for this modification in 2011, while also working closely with Central Plains Water Limited, the primary irrigation body on the northern side of the Rakaia River.
Ultimately the Lake Coleridge concept would also see further electricity generation developed via a canal that would pass through one or more additional power stations and then feed irrigation distribution infrastructure.
Chris says TrustPower’s investment in the project could be around $400 million and benefits to the Canterbury economy are expected to be in the order of $200-$300 million per annum. “It’s a big project that could have widespread benefits for TrustPower, the irrigators and the wider community. But it’s a project that will require innovative designs and clever thinking to make it work. Luckily we’ve got that in bucketloads.”