We need to get smart or more EVs could mean more climate-damaging fossil-fuel-fired electricity generation.
They claim that without more accurate electricity-pricing signals, the demand for electricity from EV owners will increase peak-load pressures on the power network, forcing costly upgrades and new generation. And they say it could even have the perverse effect of increasing carbon dioxide emissions.
In a report for three electricity lines companies, Wellington energy analyst Concept Consulting says present electricity supply contracts provide no incentives for EV owners to avoid plugging their cars in to charge in the early evening, when household power demand is already at its peak.
Simon Coates, a director of Concept Consulting, says because a “substantial amount” of the cost of network infrastructure and generation is driven by the need to meet demand peaks, those costs will increase if EV use adds to those peaks. But he says that could be avoided if EV owners had incentives to charge their vehicles overnight, when demand on the electricity system is low.
Although some EV owners do programme their cars to charge in the middle of the night, Coates says most households have power-supply contracts that charge a flat rate regardless of the time of day or night, which means vehicle owners have no incentive to charge off-peak. He says this results in a “passive” approach to charging, with most people plugging in as soon as they get home from work in the evening.
The number of EVs in New Zealand has grown rapidly from 600 in 2015 to 6600 in January this year. To de-carbonise the transport system and help meet the target of net zero carbon emissions by 2050, EVs will have to account for almost all new light vehicles entering the fleet by 2030, according to Concept’s modelling.
This increased demand will “inevitably” lead to a requirement for more generation – and the time of the day or night that EV owners plug in their cars will determine whether that new generation is renewable wind or geothermal power or whether it’s from coal or gas.
If EV charging is mostly done off-peak, then demand can be met by baseload supply and any increase in demand can be generated by new windfarms or geothermal power, says Concept. But if charging adds to or creates new demand peaks, then additional “peaking” supply will be needed – which in New Zealand, as in most other countries, is usually met by climate-damaging fossil-fuel-fired generation.
However, the report argues that if EVs were charged in a “smart” fashion, “there need not be any impact on peak demand”. A “smoothed” pattern of EV charging would also avoid heavy investment in the capacity of the distribution network.
The Concept report argues for a whole new approach to managing electricity demand for EV charging. Instead of the standard flat charge for electricity or even a two-level price structure with on- and off-peak tariffs, it argues for a “managed” system that would stagger the charging of all EVs to ensure the demand on the system is smoothed out as much as possible. This would see EV owners relinquishing control over when their cars were charged to an electricity retailer, aggregator or network company, which would have the ability to interrupt charging when demand was high. This would be similar to the “ripple control” approach to managing household hot water cylinders. Customers could be offered cheaper rates in return for handing over management of their EV charging to a third party, as well as payment for exporting power from the car battery back to the grid during periods of peak demand, suggests Concept.
The authors argue that the present flat-pricing systems reduce the incentive to switch to EVs.
In a separate report, Auckland lines company Vector has also raised the alarm about the effect of increasingly powerful EVs on the electricity system. It’s advocating for “smarter” charging systems that would also allow EV batteries to feed power back into the grid.
EVs are expected to reach price parity with fossil-fuel-powered cars between 2021 and 2025. Because they cost much less to maintain and operate, “EVs have reached a tipping point where they will fully disrupt new car sales and lead to a strong exponential market penetration”, argues Vector in its report, “Creating a new energy future”. It predicts one in 15 Auckland households could have an EV by 2021.
The newer EVs coming onto the market have much larger batteries – up to 100kWh – and can travel 350-500km on a single charge. But these bigger batteries will put a heavier load on the electricity system. They will also test owners’ patience with slow charging rates and lead to more people buying super-fast home chargers that would add the equivalent demand of up to 20 new houses to a local network.
But Steve West, chief executive of ChargeNet, a company rolling out a nationwide network of public fast-charging stations, thinks the electricity companies are raising concerns that will take years to materialise.
“Even if half of car sales are plug-ins by 2023, they still won’t make up even 10% of the fleet for at least eight years, and they won’t make up half the fleet until probably 2040. The make-up of the fleet changes very slowly, because people don’t change their cars very often. So this is not a looming problem; this transition to electric transportation is on a time scale of decades.”
West says the steadily falling price and improving performance of batteries mean it will increasingly make sense for householders to have storage batteries at home, which they can charge from the grid during off-peak periods and then use to power their homes. This development will alleviate peak load pressures, he argues.
Charging technology is also developing rapidly, he says. A joint venture called Ionity – including BMW, Daimler, Ford, Volkswagen, Audi and Porsche – is building hundreds of super-fast charging stations across Europe at which 350kWh “bowsers” can charge even large-battery cars in 15 minutes.
“By definition, if you are stopping at a [public charging station], then you are not at home cooking breakfast or dinner. When people charge in public, it is not at peak load pressure times; it’s in between … And if people are charging at very powerful charging stations, that is a much easier problem to solve, because delivering a lot of power to one location is a lot easier than it is to solve 10,000 very small problems spread all over Auckland or all over the country.”
This article was first published in the March 31, 2018 issue of the New Zealand Listener.