The boom in supermarket shopping online has led to the creation of the fastest milkfloat yet to hit the streets.

An electric delivery van has been developed (see image 2, right) that has greater acceleration than any diesel-powered equivalent and a top speed of 50mph (80km/h).

A Tyneside company that has made almost all of Britain’s milkfloats since the Second World War is switching its production line to making vans for supermarket home deliveries.

Sainsbury’s has ordered eight electric vans and has pledged to have 200 by September next year and 1,000 by 2010, allowing it to claim that none of its deliveries in urban areas will cause any air pollution. TNT, the parcel delivery company, has ordered 55 and Royal Mail is testing two with a view to converting much of its city fleet to electricity.

The battery-powered vans reduce carbon dioxide emissions by 40 per cent and can be zero-emission if the electricity is purchased from renewable sources such as wind and wave power.

One problem is that the vans are too quiet. The only sound they generate comes from the tyres on the road. With an acceleration of 0-30mph in six seconds, the vehicles could prove dangerous in urban areas.

When The Times took one for a test drive in Central London last week, it was essential to keep a sharp eye out for pedestrians. But the manufacturer, Smith Electric Vehicles, of Washington, Tyne and Wear, believes that it has a solution.

It is working with the University of Durham to produce a broadband device that projects artificially generated engine noise in front of the vehicle to alert people about to step into the road. The noise cannot be heard to the side or rear of the vehicle.

Until recent improvements in battery technology, electric vehicles have had very limited range and been suitable only for low-speed, local journeys. But the suitcase-sized sodium nickel chloride batteries in Smith’s Edison van allow it to travel 100 miles (161km) between charges with a full 1.5tonne payload, though they do take up a quarter of the load space.

It takes 45 minutes to recharge the batteries to half their capacity and they can be plugged into a normal household socket.

At £38,000, the van is almost three times as expensive as a diesel equivalent. But Smith claims that the cost of electricity per mile, at 3.5p, is a fifth of the price of diesel. Maintenance is also cheaper because there are only four moving parts compared with more than 1,000 in a diesel engine.

Like all electric vehicles, the van is also exempt from the London congestion charge and qualifies for free parking.