Whareroa Co-generation
Fonterra needed an efficient, innovative and highly reliable energy supply to fuel the largest single site dairy factory in the world. They chose Todd Energy to provide it.
Location
The Whareroa Co-generation plant was purpose built onsite at Fonterra's factory in Hawera, Taranaki. Gas is fed directly from the Kapuni production station, 22 kilometres, away via a dedicated pipeline.
Purpose
Aside from milk, the single most important element in the Fonterra operation is a highly efficient and reliable supply of energy to the factory. Fonterra were looking for a power package which was unique and could meet their strong growth.
Fonterra Whareroa needs a reliable supply of steam - over 700,000 tonnes a year. On top of this is a demand for electricity - enough to power the city of Napier.
With a 50% interest in the nearby Kapuni field and innovative approach, Todd Energy was the ideal partner to provide Fonterra with an economic, efficient and highly reliable energy supply.
History
The Whareroa Co-generation Station entered first production in 1996 as a twin 10 MW turbine plant.
By 1997 Whareroa's production and hence energy demand had exceeded expectations and a further two 10.5 MW turbines were installed in conjunction with a 28 MW back pressure steam turbine.
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 delivered energy price for consumers, but mean there are fewer emissions into the environment and consequent fuel savings for future generations.
Co-generation involves the combustion of fuel to produce two forms of energy output (typically electricity and heat or steam for manufacturing use).
Natural gas is used to drive 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 co-generation plant versus a conventional thermal plant (e.g. Huntly Thermal Station).
Diagram.
Fonterra/Todd opted for a four turbine configuration so as to provide generation redundancy and the highest possible up-time for the Fonterra dairy factory. By providing four turbines, the chances of all steam and electricity raising plant being off-line at any one time is significantly lowered.
Generating Plant
Four Solar Mars turbines drive generators to produce electricity, waste heat (exhaust heat) from the turbines is used in two John Thompson and two Innovative Steam Technologies manufactured Heat Recovery Steam Generators (HRSGs) to provide superheated high pressure steam with their electricity generation.
Additional electricity is produced using a back pressure steam turbine and step down process where steam in a high pressure state not required for factory production is converted to a low pressure saturated state for other use in the factory.
During peak dairy periods additional steam is produced by supplementary firing in the HRSGs. Additional gas is fired in the waste heat stream scavenging the remaining oxygen to lift the heat output of the turbine waste heat step and thus allowing increased boiler steam production.
