Kapuni Cogeneration Station

The Kapuni Cogeneration Station allows local Hawera industries to combine their load and enjoy the benefits of onsite embedded generation.

This 50:50 joint venture between Vector and Bay of Plenty Energy is another example of the commitment to local generation projects.

• Station Location
• Station Purpose
• Station History
• Benefits of Station
• Generating Plant
• Station Statistics

Location

The Kapuni energy center is located at the Vector Kapuni gas treatment station.

Kapuni is approximately 85 kilometres south of the city of New Plymouth.

The site is adjacent to the Kapuni gas and condensate production station owned by Shell/Todd while being close to high energy users such as Lactose New Zealand (a Fonterra company).

Purpose

The plant provides heat and power for local industry. The plant has a rated output of 25 MW. Of this 20 MW is exported to the national grid.

Some 490,000 tonnes of steam a year is also produced for use in the Vector Kapuni Gas Treatment Plant. This steam allows Vector's Benfield plants to strip carbon dioxide from Kapuni gas to maintain pipeline specifications.

Steam excess to Vector's needs is transported via a dedicated 3 km long steam line to Lactose New Zealand's dairy processing plant.

History

The Kapuni Cogeneration Station was first commissioned in 1998. Since that date incremental improvements have been undertaken to the plant.

Todd Energy, in conjunction with Pacific Hydro Ltd. became 50:50 shareholders in Bay of Plenty Energy in 1999.

Benefits

Environmental efficiency can be achieved by using new generation technology. Smaller "embedded" generation units allow savings to be made while more efficiently using input fuel.

By producing heat and electricity onsite, losses due to transportation of the electricity or conversion into heat/cooling or kinetic motion are avoided. These savings not only bring about a lower end energy price for consumers, but mean there are fewer emissions into the environment and consequent fuel savings for future generations.

Cogeneration involves the combustion of fuel to produce two forms of energy output (typically heat or steam for manufacturing use and electricity).

Natural gas is typically used to drive gas turbine generators equipped to with a heat recovery boiler, which captures the thermal energy from the turbine's exhaust and uses it to make steam.

The efficiencies of a cogeneration plant versus a conventional thermal plant (e.g. Huntly Thermal Station) can be gauged by the diagram on the right.

Generating Plant

The Station consists of two 10 MW Solar Mars turbines which are fueled with treated Kapuni gas from the Vector gas treatment plant. The gas turbines, in addition to two steam turbines, produce approximately 25 MW of electricity of which 20 MW is exported to the national grid.

Waste heat steam from the gas turbines is used by Vector in their gas treatment process at Kapuni. This amounts to some 490,000 tonnes per annum. This steam is passed through a 1.5 MW back pressure steam turbine to achieve heat and pressure levels required by the factory and generate further electricity in the process.

Residual steam is transported via a three kilometre insulated steam pipeline to Lactose New Zealand at 34 bar. This steam is used in their dairy factory and final generation is undertaken via a 3 MW back pressure turbine located at the Lactose site.

Electricity is supplied to Lactose via a dedicated underground 11 kV ring main circuit.

Statistics

Ownership	50% Ownership Bay of Plenty Energy (BoPE)
Fuel Supply	Treated Kapuni Gas
Total MW rating	25.3 MW
Gas Turbines Type	2 at 10.3 MW Solar Mars Ltd. Turbines
Steam Turbines	Type 1 at 3.2 MW back pressure turbine 1 at 1.5 MW back pressure turbine
Generator Voltage	11,000 Volts
Peak Steam Output	90 tonnes/hour