Energy-efficient hybrid electric vehicles will only become competitive in the New Zealand car market in about seven years, an electrical engineering expert said Thursday.

Electric vehicles were still too expensive for New Zealand, but the country could benefit substantially from them in terms of reduced greenhouse gas emissions and reduced air pollution, University of Canterbury researcher Dr. Allan Miller said at the national energy conference in Wellington.

"The price of an electric vehicle is largely determined by the cost of the battery system. Until this cost is reduced by improved technology and increased manufacturing volumes, they will remain prohibitively expensive," Miller said, according to a statement from the university.

"The key tipping point at which the battery cost per kilowatt- hour drops below an affordable level is expected to occur around 2020. This will result in these vehicles reaching near price- parity with standard vehicles and consequently increasing market volume."

Hybrid vehicles had been on the New Zealand market for about 10 years and offered considerable fuel savings, but the 5,000 to 6, 000 registered hybrids made up just 0.2 percent of the New Zealand fleet last year.

Even if the balance tipped in favor of electric vehicles now, at the current rate, it could take 50 to 100 years to replace the 2.6 million private vehicles currently in New Zealand, he said.

The University of Canterbury was conducting a project that would lead to a national smart grid project, funded by the Ministry of Business Innovation and Employment.

Electric vehicles had the lowest operating cost per kilometer of petrol, diesel and hybrid vehicles, but they still had a limited driving range and recharging time, which could only be addressed by improved technology and infrastructure, Miller said.

"Despite all the interest and excitement around electric vehicles, New Zealand will have to wait. We are simply not able to decrease prices or encourage uptake in an efficient and affordable manner. Instead, we should keep an eye on global developments and take action when it is economically appropriate," he said.