While the government won’t put a figure on EV power demand, a quick estimate shows it could be as much as 8 TWh if all vehicles were electric by 2035.

The government has brushed off questions on how much power Hong Kong’s electric vehicles will consume, failing to put a figure on the energy thirst of potentially millions of electric cars, trucks and buses speeding around the city.

Transit Jam first sought such figures at the launch of the government’s Roadmap on Popularisation of Electric Vehicles in March, asking Environment Secretary Wong Kam-sing how much electricity Hong Kong’s electric vehicles would use by 2030 and 2035. Wong dodged the question and said the power consumption would be relatively small and that government was working with power companies to ensure demand could be met.

Environment Secretary Wong Kam-sing inspects new facilities as part of a HK$2 billion subsidy for electric vehicle parking upgrades at a luxury apartment blocks

On a follow-up email with Environmental Bureau, with a request for specific figures on power consumption, a spokesperson again evaded the question and said the government was in “close contact” with power companies. “Based on our estimation of the power demand in connection with the rise of EVs from now to 2035, its ratio will be small (i.e. around a few per cent) as compared with the power supply capacity in Hong Kong.”

The spokesperson again refused to put a watt-hour number on the estimated electricity consumption of electric vehicles in the city, either for the present time or for 2035 and beyond, or to answer questions on whether the electricity powering such vehicles would be zero carbon in line with Hong Kong’s 2050 carbon neutrality goal.

But other countries popularising electric vehicles have found that an EV fleet can use considerable power, and that while electricity generation can ramp up to avoid shortages, electricity grids may not be able to cope with the shifting patterns of demand.

In Norway, the world leader in terms of electric vehicle adoption, analysts estimate the electricity grid will need a US$1.1 billion (HK$8.6 billion) upgrade to cope with the power surge from EV charging, with consumers set to foot the bill. The Norwegian grid investment estimate isn’t even for additional electricity generation but necessary improvements to low-voltage networks, substations and high-voltage grids.

Norway’s estimated electric car fleet of 1.5 million could suck 5 TWh from the grid by 2030, says engineering consultant Poyry, with other consultants estimating 11 TWh (a quarter of Hong Kong’s 2019 electricity consumption) by 2040. In fact, through its promotion of electric cars, and electricity to heat its buildings, Norway has become the world’s second-highest consumer of electricity, per capita, beaten only by Iceland.

Consultants in Norway say a grid re-build could be avoided by enforcing strict “night charging” for EVs, while allowing only nighttime or afternoon charging on empty batteries could reduce the revamp cost to US$0.5 billion (HK$3.6 billion). But without such strict measures in place, the costly upgrade is inevitable.

A back-of-the-envelope calculation based on Hong Kong’s road miles driven and assuming a typical 160 Wh/km for cars and 1.6 kWh/km for trucks and buses shows Hong Kong would need around 6 TWh – around 14% of its 2019 electricity consumption – to power all its vehicles by electricity today. By 2035 that would have grown to 8 TWh, 18% of the city’s 2019 electricity consumption.

For its part, the Hong Kong government has said it would assume electric vehicle owners would charge their vehicles at night, so as to not overload the grid.

“In addition to the Government’s overarching policy of encouraging owners of electric private cars to charge at home or workplace, charging EVs, in many cases, is using non-peak supply of power and shall not overload the power supply system,” said a spokesperson.

But there is yet to be discussion on whether this home/night charging will be mandatory or how it would be encouraged. Under the government’s subsidy scheme to build charging stations in private residences, there are no limits or rules on charging hours or schedule.