Who needs oil?

London has another pressing reason to move on from oil. The government's advisory Committee on the Medical Effects of Air Pollutants has reported that levels of the tiny particles that damage health the most are 50 per cent higher in Central London than across England and Wales as a whole. Getting rid of these particles, it estimated, would add nine months to the life expectancy of newborn Londoners. A study by the Institute of Occupational Medicine calculated that particle pollutants may have been responsible for over 4,200 deaths across London in 2008. Getting rid of oil, says Professor Martin Williams of the Environmental Research Group at King's College London, 'would have a massive effect.' He has modelled the effect of reducing London's fossil fuel use by half: 'It halved the levels, which meant half as many deaths.' Ending oil use entirely would clear the air of all the particles emitted by vehicles except those from the tyres and brakes.

The main candidates to replace oil on the roads are batteries and hydrogen; the latter first as a fuel for internal combustion engines and in the longer term for cells powering electric motors. While batteries lack range and aren't yet up to hauling London's bus passengers, an increasing prevalence of hybrid vehicles and charging points could well encourage London drivers to go electric. After all, they are used to journeys that don't go very far or very fast - 90 per cent of London car trips are less than six miles, says Source London. 'Cities are a natural home for electric vehicles given where the technology is at the moment and is likely to be over the next little while,' says Isabel Dedring from the Mayor's office.

Professor Neal Skipper, of the London Centre for Nanotechnology at University College London, agrees that electric vehicles will establish themselves first, but sees hydrogen as part of the post-oil transport mix. He co-founded a company, Cella Energy, which is using nanotechnology to store hydrogen in solid materials: in microscopic pellet form, they could be pumped like petrol.

The decline of oil will doubtless spur a host of innovations like these, many of them based on genetic manipulation or nanoscience. They will be ever smarter, but they may never be cheap. 'I think the level of fuel price that we have at the moment is probably where we can get back to,' Skipper says. A breakthrough such as a leap in the performance of solar panels might do the trick, he suggests, 'but the mechanisms do involve a bit of wishful thinking.'

Whatever it costs, it'll be worth paying. London's population could reach about 8.5 million by the mid-2020s. Defra's UK Climate Projections suggest that by the middle of the century London's mean daily temperatures will be 2.5C to 3C higher in summer than they are now. By the 2080s London summers could be as hot as New York or Naples summers are today. A hotter, denser capital will have to be smart, efficient and clean if it is to be a good place to live and work. The sooner it moves on from oil, the smarter and happier it is likely to end up. ES

London 2050 - A vision of city life

London has moved on from oil, and changed its shape. The capital's watchword now is efficiency, applied both to energy and to space. Homes are more densely packed, both because more people live in London and because party walls help to conserve energy, by reducing the surface area through which heat can pass in and out of buildings. Apartment blocks thrive, though in many districts their height is limited by regulations passed to quell disputes about overshadowing - blocking sunlight cuts off a building's solar power supply. Architects have also rediscovered imposing terraces, whose size allows dense occupation and whose mass helps keep temperatures even: the signature housing form of the mid-21st century is the form that led London's great expansion across the fields of Notting Hill and Islington two centuries before. The scarcity value of a detached house has made the few surviving 1930s villas highly exclusive properties.

Journeys are shorter, saving energy and avoiding congestion. The Victorian capital, feeding into a central core from all directions, has been reorganised into a net, with lots of local centres where people work as well as live. There are no suburbs: the city is a huge cluster of towns that are self-contained but richly interconnected with everywhere else by communications technology. People work at home or, more often, at desks rented by their distant employers in local offices.

They rarely drive. Although many people still travel in cars, they are largely passengers. Automated systems marshal vehicles into co-ordinated platoons, control speeds, and grant access to roads on the basis of need. London's transport is dominated by electricity and electronics together. To enjoy the sensation of controlling a vehicle, people get on their bikes.

Efficiency means integration and co-ordination. London's electric cars are part of its power network, feeding spare electricity back into the grid to help balance supply and demand. Solar-power cells cover most of the city's surfaces that aren't painted white to reflect heat, but the wellspring of London's electricity is the Thames Estuary, with its winds and tides. The whole system, from the great turbines in the Thames to the tiny automatic controllers that open windows or switch off appliances, is a super-smart grid that regulates the capital's metabolism. Energy is closely policed, too. Surveillance drones use infra-red sensors to detect air-conditioning, which is illegal.

The streets are tidy now that the throwaway economy has been replaced by thrift and bioplastic is costly. London's green life is more diverse because the air is clean - though oaks and willows are excluded, as they produce ozone in hot weather. Southern species like sweet chestnut flourish in the warmer climate. Leaves cover glass walls in summer, then fall to let in the winter sun. Green roofs absorb rain, helping to prevent floods. The distinction between the vegetable and the mineral parts of the city has become blurred. And the roses climbing around doors hark back to a mythical village past, defying the fact that most of them are on office blocks.

Although the Victorian structure of the city has been undone, most of the pre-1914 buildings that survived the 20th century are still standing - the large ones, such as Selfridges or the grand terraces of Pimlico, because their mass is suited to a warmer climate, and the smaller houses because they are occupied by their owners, who are not in a position to demolish and rebuild their homes. Fortunately, nanotech insulating materials give Victorian houses 21st-century performance while preserving their 19th-century appearance. But they are a reminder that it hasn't been quick or easy to get here. The railway upgrades and motorway repairs of the early 21st century were like changing lightbulbs by comparison.

And what is it like to live in this clean, computer-co-ordinated capital? Do Londoners play their part in the great network as active, willing citizens, or do they sullenly allow themselves to be adjusted as the system instructs? That is a whole other story - and perhaps as big a challenge as taking the carbon out of the economy.
Marek Kohn's Turned Out Nice: How the British Isles Will Change as the World Heats Up is out now (Faber, £14.99)