Nova Energy uses co-generation technology to increase energy efficiency at commercial and industrial sites and is one of the largest owners of co-generation plants in New Zealand.
Co-generation involves the combustion of natural gas to create electricity, with the waste heat from the combustion process utilised to provide process steam or hot water. Co-generation plants have a fuel usage efficiency of up to 80%, which well exceeds the efficiencies of 30–55% achieved by conventional thermal electricity generation plants. Having onsite co-generation provides improved security of supply; reduces loss from transmissions and is energy efficient using technology that equals or exceeds international best practice for minimising greenhouse gas emissions.
The Whareroa co-generation project is an example of Nova Energy's ability to provide a total energy package for New Zealand industry.
Fonterra’s Whareroa site at Hawera collects up to 14 million litres of milk a day from across New Zealand. It produces the largest volume of dairy ingredients, from a single factory anywhere in the world. Aside from milk, the single most important element in the Whareroa operation is a highly efficient and reliable supply of energy.
Fonterra sought a company with the insight to understand its energy requirements and with the expertise and resources to meet them.
What Fonterra needs is steam - a million tonnes of it a year - and enough electricity to power a city the size of Napier. What Nova Energy has is gas. The marriage between the two is a gas-fired co-generation plant that supplies all of its electricity.
A specially constructed 22 kilometre long pipeline transports 5 petajoules of gas a year (2½ times as much as used by the whole of Wellington city) to the plant - as well as supplying other Nova customers with gas along the way. The co-generation plant produces 380 GWh of electricity a year.
Exhaust heat from the turbines is channelled through giant heat exchangers to produce steam - enough to meet the needs of the Whareroa Factory. And in the off-season, when steam demand is lower, the surplus is diverted to a steam turbine to generate further electricity which feeds into the national grid.