The ferry takes passengers on the 15-minute trip between Lyttelton and Diamond Harbour about 40 times a day, with more than 290 scheduled trips each week.

In 2019 local authorities said they were looking at a battery-electric ferry to replace the diesel one, which was nearly 20 years old.

At the time, Christchurch City Council said it would provide a $45,000 grant towards a battery electric ferry, while EECA would provide $200,000 towards the project.

The short trip time and access to charging at Lyttelton Port were touted as “ideal.” Black Cat Cruises, who operates the ferry, said going electric would reduce engine noise in the harbour, which is a marine mammal sanctuary, as well as vastly reduce greenhouse emissions.

However, last month Environment Canterbury launched a new diesel ferry, the Black Pearl, instead of the electric vessel many community members had been hoping for.

Thomas Kulpe, spokesperson for Lyttelton Energy Transition Society, a local group formed to promote renewable energy, says ECAN’s decision not to make the switch to electric was a missed opportunity, and at odds with the region’s climate targets.

“It’s very disappointing. [The upfront cost of an electric ferry] may have had an impact on the rates, but at the moment our children and grandchildren will be paying for it. And it’s a big cost to bear.”

Environment Canterbury declared a climate emergency in May 2019, and last month launched its first Climate Action Plan.

What went wrong?

ECan had decided not to opt for an electric ferry in 2020, during the uncertain early days of the COVID pandemic.

Sonia Pollard, ECAN Public Transport acting general manager, told Carbon News they had considered an electric ferry. “But initial forecasts predicted annual running costs of about $100,000 per year more than a diesel ferry, plus an additional one-off cost of $550,000 for charging infrastructure.

“Something else that played a part in our decision was that we expect to relocate the ferry operation to a new site further in the inner harbour within the next three years. This would result in more set-up costs if we needed to move charging infrastructure.”

At the time of the purchase, only one electric ferry was in manufacture in New Zealand, and none were in operation.

Pollarad also cited significant budget blowouts for electric ferry projects elsewhere in New Zealand. “We understand that Greater Wellington Regional Council experienced significant cost over-runs with an electric ferry.”

However the ferry in question, Wellington’s Ika Rere (Flying Fish), which has been running since early 2022, has been praised for saving its operator money in fuel, as well as reducing emissions by about 80%.

Pollard said the council was focussing investment “for now” on replacing diesel buses with zero emission buses, “for which the technology is more mature and continues to decrease in cost.”

She said that while the new ferry has double the passenger capacity of the old ferry, initial estimates are that it is far more efficient and will only increase fuel consumption by 10%.

“Our calculations also tell us that by taking the ferry from Diamond Harbour to Lyttelton, followed by a bus to the city, 8.7 kg of CO2 exhaust is saved per trip compared to driving the same route by car.”

Pollard would not say how much the new ferry cost, as it was commercially sensitive, and commissioned and paid for by Black Cat, which operates the ferry. “But our initial review found it would have been up to two times the capital cost to build an electric vehicle.” 

She said that emissions information for the new ferry was not yet available. However, early investigations from 2019 suggested that switching to electric would reduce the ferry’s greenhouse emissions by about 344 tonnes per year.

Kulpe, of Lyttelton Energy Transition Society, notes that the council’s current Regional Public Transport Plan to 2028 says that ECAN’s public transport fleet would be fully transitioned to zero emission vehicles by 2030.

“That is just six years away. Given that the lifespan of a bus or ferry is around 20-25 years the Black Pearl is likely to be with us way beyond 2030 possibly up to 2050.”

“Our own emission reduction efforts put us on a trajectory to a 3ºC+ warmer world. We have to do better.”

The Black Pearl is contracted to Environment Canterbury until 2032.

The council previously used biofuel for its other ferry, Black Diamond, however this stopped as the supply was no longer available.