Polytechnic opts for cleaner heating

The Otago Polytechnic has decided to replace the coal-fired heating system for its Dunedin campus with wood chip and lpg boilers, despite the alternative fuels being almost a third more expensive than coal.

It cost about $300,000 a year to run the coal-fired boilers in 2009 and last year, while wood chips and lpg were expected to cost about $390,000 per annum, chief operating officer Philip Cullen said.

Some of the additional cost would be offset by lower repairs and maintenance costs once the new boilers were installed, he said.

But the main reason for going with wood chips and lpg was because of the polytechnic's pledge to environmental sustainability.

"We are not prepared to continue using the dirtiest of fuels ...

At least with wood chips we are using a renewable resource. You can always grow more trees."

The polytechnic has been investigating replacement boilers since mid 2009 when it learned the existing ones would not receive new air discharge consents from the Otago Regional Council when the present permits expired.

At first, converting the present boilers to run on wood chips was investigated, but Mr Cullen said conversion was not possible because emissions from the boilers would still exceed ORC limits.

The ORC consents ran out in October last year but were extended until March next year to allow time to settle on the best replacement system, he said.

A feasibility study showed two wood-chip burners would heat the campus but the system would work best if heating was boosted by an additional lpg-fuelled boiler. The system met emission requirements and would receive air discharge approval for the next 35 years.

The coal-fired boilers also heat the University of Otago's Forth St College of Education campus, with the university paying the polytechnic an annual contribution towards operating costs.

Mr Cullen said the university had not decided whether that arrangement would continue. If it did, the polytechnic would seek at least a 10-year commitment from the university towards the cost of the new boilers and annual running costs.

Larger boilers, a bigger wood-chip storage bunker and plant room would be required if the university was involved, he said. The cost would also be greater - $1.65 million compared with $1.35 million.

In order for the polytechnic to meet its ORC deadline, the university would have to decide within the next two weeks whether or not it would be involved, he said. It was hoped the new system would be installed and operational by February.