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The Clocktowers clockThursday 8 October 2015 9:04am

Janet Stephenson image
Dr Janet Stephenson, report co-author

A new study commissioned by the Otago Chamber of Commerce has assessed how much energy Dunedin uses as a city, and from which energy sources it is most reliant.

While commissioned by the Chamber, the Dunedin Energy Baseline Study was co-funded by the Dunedin City Council and the Centre for Sustainability at the University of Otago.

Using data from 2014, Dunedin's total energy inputs comes to approximately 10.5 Petajoules – a measure of electrical, mechanical, and thermal energy.

Of this, 58% was petrol and diesel, 31% electricity, 5% coal, 3% LPG, and 3% wood fuels. Fossil fuels (coal, diesel, petrol and LPG) were the dominant source of energy driving the city, accounting for 66% of all energy used, and 86% of energy-related greenhouse gas emissions.

“To help put this in perspective, 10.5 Petajoules is approximately the same amount of energy as contained in 300 million litres of unleaded petrol, which would be the volume of about 120 Olympic swimming pools” says report co-author Prof Gerry Carrington.

“At a rough estimate, the value of energy inputs into the city for 2014 was in the region of $500 million: around 10% of Dunedin's GDP.”

The 50-page report from the study describes the energy inputs to Dunedin (including the rural parts of the city) during 2014, some of the main end-uses of the energy, and the greenhouse gas emissions produced.

“We wanted to know how much we use as a city, where it comes from, and what it is used for,” says Dougal McGowan, CEO of the Chamber.

“We need that information as a city to help plan our future, because energy is such a crucial resource for businesses and households.”

“The information wasn't easy to find, as this kind of project hasn't been done before in New Zealand” says Research Assistant Dr Cle-Anne Gabriel, who carried out most of the research.

“I spent a lot of time interviewing local companies involved in supplying different fuels, digging into national energy data files, and looking through dusty boxes for fuel tax data. There are still a few bits of data missing, like how much firewood people gather themselves, but the big parts of the puzzle are in place,” she says.

“The report really helps us understand the big picture of energy supply into Dunedin city, and invites us to think about what we might need to do to become more resilient”, says Scott Willis, Chair of the Chamber's Energy Committee.

“For example, petrol and diesel make up more than half of the total energy supplied. This suggests that Dunedin has some vulnerability to price volatility in these imported fuels, and that we should seek opportunities to reduce that risk.”

Around 86% of Dunedin's electricity supply was generated from renewable resources. Dunedin's electricity was predominantly sourced from the national grid (68%), but the power supply from the Waipori (hydro) and Mahinerangi (wind) generation schemes enters the grid within the DCC boundaries at Berwick, even though the electricity is generated with Clutha District. This provided nearly 32% of the total electricity used within the city in 2014.

Within the city there are many sites where small amounts of electricity is generated (including the DCC's methane-to-electricity scheme at the Green Island landfill, several other industry-based generation schemes, and household-scale wind and solar installations) but these only contributed 0.2% of electricity supplied to the city. However solar generation capacity increased during 2014 by 280% to a total of 119 solar connections (with combined installed capacity of 0.395 MW). This is the main energy supply where significant change was seen during the year.

Almost all of the energy supplies were sourced from elsewhere in New Zealand or from overseas. Dunedin's liquid fossil fuels (petrol, diesel and LPG) were shipped in; the coal was transported in from various mines in the South Island; and the firewood sold commercially was sourced from forests outside of Dunedin. Less than 0.1% of total energy was sourced from within the city boundaries.

The report also identifies new business opportunities. For example, approximately 1500 tonnes of wood pellets were supplied to Dunedin customers in 2014, and around 150-200 new pellet fires are installed annually. Despite the fact that Dunedin has a number of major forests, there is no local production of pellet fuel; it is all currently imported from manufacturers in Taupo, Nelson, Timaru and Tapanui.

“Having the baseline study means the city can now see where our energy comes from, track how this changes in future, and help identify opportunities to use energy more productively” says Dougal McGowan.

“We've only just scratched the surface with this report” says report co-author Janet Stephenson.

“There's lots more that could be done that were beyond the scope of this project, such as calculating the value of the energy inputs into Dunedin, filling in the 'black holes' where we couldn't find data, and identifying more precisely where the energy is used. Mapping the energy flows in Dunedin would enable us to spot energy that currently goes to waste or could be used more efficiently. An example is identifying waste heat from industrial processes which could potentially be used by other industries.”

The Dunedin City Council's General Manager Services and Development, Simon Pickford says the Energy Baseline Study is an important complement to the draft Energy Plan 1.0, an action under Dunedin's Economic Development Strategy, and the long term aims of Dunedin's draft Environment Strategy. “We're enthusiastic about the report and very pleased about this successful joint project involving the Council, University and Chamber of Commerce.”

View the report

For further information, contact:

Dr Cle-Anne Gabriel
Centre for Sustainability
University of Otago
Tel 64 3 479 5220

Scott Willis
Chair, Energy Committee
Otago Chamber of Commerce
Tel 64 274 888 314

Simon Pickford
General Manager Services and Development
Dunedin City Council
Tel 64 3 477 4000

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