PARIS (Reuters) - A consortium of French companies led by construction firm Bouygues has developed an electric car charging system based on old batteries that helps smooth out power demand when dozens of cars simultaneously recharge.
A typical charging station of the popular Paris Autolib self-service rental cars has four to five charging plugs, which each make no more demand on the power grid than an average home.
But imagine a firm or institution where dozens of employees arrive in the morning and all start recharging their cars at the same time. That would put a huge strain on the building's power network and force it to upgrade its electricity connections.
The Eco2charge group, which also includes car maker Renault, electrical engineering group Alstom and cable maker Nexans, has developed a charging system that assembles old batteries from electric vehicles into a power storage bank that can soak up electricity at night and gradually charge vehicles during the day.
The project, which has a 13 million euro ($16.8 million) budget, has been trialed in two Bouygues and Renault pilot sites and the group aims to sell it to office buildings, parking lots, campuses and other sites where fleets of electric cars can park.
"In about a year we will have a commercial offer," Bouygues Energy and Services director Servan Lacire said, adding that it was to soon to say how much the system would cost.
For storage, Eco2charge will use end-of-life Renault electric vehicle lithium-ion batteries. Renault, which sells electric cars but rents the batteries to their owners, owns and manages some 47,000 batteries from four different models.
Once the batteries have lost 20 to 25 percent of their charging capacity, they are no longer used in cars, but still have enough charging power for stationary power storage.
"It is a very cheap form of storage, as the cost of the batteries has already been written off for use in the vehicle," said Thomas Orsini, head of electric vehicle business development at Renault.
The charging system will work for all brands, not just Renault, he added.
The car maker is also looking at developing utility-scale power storage systems, that would assemble as many as 50 recycled car batteries into one container for use with large solar power stations or wind parks.
The system could likewise be part of a grid-wide demand-response system, and in the future it should also be possible to not only temporarily stop drawing power from the grid, but also to feed back power into it at times of peak demand.
Nexans's Alain Robic said the stations will be modular "like Lego blocks" so that companies can install anything from half a dozen to 100 or more.
Utilities across Europe are very eager to boost usage of electric cars as they see it as a way to boost power demand, which has been flat or falling due to the economic crisis and increased energy efficiency.
IHS Automotive estimates that in 2014, car makers worldwide will produce more than 217,000 battery electric vehicles, or 0.25 percent of a global production forecast of 87.7 million vehicles, rising to nearly a million electric vehicles, or 0.9 percent of a forecast 104 million vehicles, by 2020.
Across Paris, Autolib operates some 2,500 cars and nearly 900 charging stations. It has several competitors, including Wattmobile, which opened a new charging station in the French capital on Thursday.
($1 = 0.7745 euro)
Additional reporting by Laurence Frost; Editing by Crispian Balmer