6) Chinese Say They're Building 'Impossible' Space Drive

Musk has a track record of successful technological leaps. He co-founded the online money-transfer company PayPal, and made his millions when it was sold to eBay in 2002. He is co-founder of the rocket company Space Exploration Technologies (SpaceX). Then in 2004 he decided to invest part of his new-found fortune in tackling what he considers to be one of the most important challenges of our age: cutting CO₂ emissions from road transport. This sector is responsible for emitting one-fifth of global greenhouse gases. Musk weighed up the options and concluded that the most efficient way of cutting emissions was to build an electric car. He has become an evangelist for the technology. "In 30 years' time, the majority of cars in the US will be electric," he declares.

Time will tell whether Musk is right, but he has already achieved his first goal. A handful of Tesla Roadsters are now on the road, about 1000 have been ordered, and the model has already become a poster child for electric cars. With a top speed of 210 kilometres per hour (130 miles per hour), and an abilty to accelerate from 0 to 100 km/h in about 4 seconds, it has banished the pootling golf-cart image that dogged its predecessors.

What's more, it has maintained impressive green credentials. The Roadster produces no CO₂ exhaust emissions, and even when you factor in the CO₂ released in generating the electricity used to charge its batteries it produces less than half the amount of that emitted by the greenest gasoline cars on the market. Generating electricity from renewable sources would cut the Tesla's CO₂ footprint still further. And it's cheaper to run than a gasoline-powered car - Tesla estimates it costs less than 2 cents per kilometre. One kilometre in a conventional car with a fuel consumption of 9 litres per 100 kilometres (26 miles per US gallon) - with gasoline at $3.60 per gallon - costs more than 8 cents.

However, at $109,000 apiece, Tesla Roadsters are aimed squarely at people with money to burn. It's designed to show that electric cars can be fun and sexy, not to be a practical runabout. Musk doesn't deny this. "I've no interest in the Roadster itself," he says. "It's a means to an end." Or, in other words, a proof of principle. The company's next car, which Musk predicts will be in production within three years, will be a family-sized sedan which he estimates will cost around $60,000. After that comes a compact version of the same car for $30,000.

It's a bold ambition. But are all-electric cars like these the best replacement for the gas guzzlers that dominate our roads? And if they are not, what is the best way to make a cheap low-emissions car without compromising on the comfort and performance consumers have come to demand?

The Tesla Roadster is certainly not the only design vying to knock conventional cars from pole position. With oil prices still far higher than we've been used to - and reducing CO₂ emissions and cutting reliance on foreign oil at the top of the political agenda in the US and elsewhere - kicking the gasoline habit has become a priority for drivers and politicians alike. And with sales of gas guzzlers falling fast (see chart), mainstream car manufacturers are finally waking up to the message that lean, green cars are what people want.

The race is on to build the lowest-emissions vehicle, and car companies are hedging their bets with a spectrum of new technologies, each with its own pros and cons. In the past, the biggest fork in the road lay between all-electric cars on the one hand, and hydrogen-powered cars on the other. It may even be a hydrogen-electric hybrid that ultimately carries the day. But there are plenty of doubters with regard to both technologies.

Musk, for one, is adamant that hydrogen is a waste of time and will never match the capabilities of all-electric battery-powered cars (see "Whatever happened to hydrogen?"). Yet this July, Honda launched its first commercial car powered by hydrogen fuel cells - the Honda FCX Clarity - in Musk's home town of Los Angeles. Honda initially plans to lease 200 cars over three years, at a cost of $600 per month. BMW began a similar scheme last year, leasing 100 dual-fuel cars that can burn either hydrogen or petrol in their customised internal-combustion engines. Hydrogen still has a long way to go though, not least because the refuelling infrastructure is sorely lacking, with just 26 hydrogen refuelling stations across California to date, and only 150 worldwide.

Perhaps the biggest surprise announcement has come from General Motors, the company that brought us the ultimate gas guzzler, the Hummer, and only five years ago voluntarily destroyed its own fleet of low-emissions electric cars, dubbed the EV1 (see "The resurrection"). "We believe the ultimate solution is the electrification of the automobile - as soon as possible," said Jon Lauckner, a GM vice-president, at a green vehicles conference in San Jose, California, in July.

GM clearly has some catching up to do. In April this year, Toyota announced that it had sold its millionth Prius - its flagship low-emissions car. The success of the Prius has spurred GM to rework plans for a new plant in Mississippi. Instead of gas-guzzling SUVs, the plant will make cars that operate on a similar principle to the frugal Prius.

Unlike the Tesla, the Prius has a hybrid propulsion system that combines a gasoline-powered internal combustion engine with a battery-powered electric motor. At up to 25 km/h or so, the Prius runs near silently on its electric motor. Accelerate beyond that and a regular petrol engine kicks in, giving a combined fuel economy of about 5.1 l/100 km. Energy from the engine and energy recovered during braking tops up the battery so there is never any need to plug the car into the mains electricity grid.

The Prius uses nickel-metal hydride (NiMH) batteries - a tried and tested battery technology common in portable radios and other gadgets, and one that GM briefly employed on the second generation of the EV1. A few design changes, such as larger conductors within the cell, allow the batteries to deliver the tens of kilowatts needed to drive a car. They are also about half the weight of the equivalent lead-acid batteries - the type used in the first EV1s. While these accounted for about one-fifth of the mass of the EV1, the Prius batteries can be made much lighter as they only back up the gasoline engine, rather than replacing it completely. NiMH cells also last much longer than lead-acid batteries: some are still running after 10 years of regular recharging, says Ahmad Pesaran, an engineer at the National Renewable Energy Laboratory in Golden, Colorado.

Demand for the Prius in the US is so high that the cars gain in value in their first year, as people pay over the odds to avoid the waiting list for a new one - something almost unheard of with mass-market cars. Together with hybrids from several other manufacturers, these vehicles are making a difference. Toyota calculates that the cars have already saved 4.5 million tonnes of CO₂.

But that's just the start. Over the past decade, engineers have been tinkering with the design of an even more efficient type of battery. This is the lithium-ion (Li-ion) cell, the kind used in laptops and cellphones. The result is lithium-ion batteries that can dramatically outperform NiMH cells, carrying about twice the energy for the same mass (see "Powering the next generation"). Some pre-production units are now in the final stages of testing. Pesaran estimates that the Li-ion cells will withstand 5000 recharge cycles. NiMH cells can take about 3000.

Li-ion batteries are still expensive, but according to analysts at the investment bank Morgan Stanley a new generation of batteries will help reduce their price and thus lead to cheaper hybrids and drive worldwide annual demand for the cars to 3 million by 2020. Last year 347,000 hybrids were sold in the US (see graph).

Plug in, switch on, drive off

While the existing Prius needs to continually recharge its batteries using its engine and regenerative breaking, the next generation of hybrids is likely to have higher battery capacity and be chargeable directly from the electricity grid. These are the so-called "plug-in hybrids". Prius enthusiasts who can't wait for the car's next incarnation are already beefing up their Priuses with off-the-shelf systems (see "Pumped-up Prius"). Plug-ins are likely to be the easiest way to begin cutting transportation-derived greenhouse gas emissions without the need for a new refuelling infrastructure which, for example, hydrogen would require.

A study by the Electric Power Research Institute (EPRI) in Palo Alto, California, concluded that hybrid cars charged with electricity produced in fossil-fuel power stations would still produce less greenhouse gas emissions than conventional cars (see chart). Another study, led by Michael Kintner-Meyer at the Pacific Northwest National Laboratory in Richland, Washington, calculated that the existing US electricity-generating infrastructure has sufficient capacity to supply 70 per cent of all car journeys if they were made in electric vehicles, without adding any new power stations. That's assuming that most cars are driven for less than 42 kilometres per day. On paper, at least, the message seems clear: to save the planet, go electric.

Can it be done without us all driving around in golf carts? That's what Musk wants to demonstrate with his Roadster. Its batteries can deliver 185 kilowatts, or around 250 horsepower - about the same as a Porsche Boxster sports car. And the vehicle is wonderfully quiet: when I got behind the wheel and turned the key I was taken aback by the silence. Slinkiness aside, a single charge will take it 330 kilometres, which is more than most commuters travel in a week.

If Li-ion batteries perform so well, why not ditch petrol engines altogether? "The big question, the number one question, is cost," says Mark Duvall, an expert in electric vehicles at EPRI. A closer look at the Tesla explains why. The vehicle is not expensive by sports car standards, but the overall price conceals the cost of the 7000 or so Li-ion cells that make up the battery. Tesla will not comment on the cost of individual components, but Duvall estimates the battery alone would cost around $20,000 - as much as a conventional mid-range family car. Even so, Tesla's battery is cheap for its size because the company uses off-the-shelf cells already mass-produced for mobile devices. This presents another problem: wiring all these cells together creates a complex system that has multiple potential points of failure. Car manufacturers may baulk at the thought, preferring to keep things as simple as possible. So instead several are working on new designs consisting of about 10 cells. Unfortunately, kilogram-for-kilogram, these cells currently cost more than twice as much as existing off-the-shelf batteries.

Nevertheless, their greater simplicity and increased reliability are valuable factors. Tesla plans to adopt the technology in its next generation of electric cars. Using a smaller pack will also help keep costs down, giving their planned sedan a range of 250 kilometres between charges. But recharging will still be a problem. Recharging Tesla's existing Li-ion battery pack from the domestic supply, for example, takes about 3.5 hours.

Supporters of electric cars argue this shouldn't stop affordable ones finding their way onto the market because most people rarely need to drive long distances. In the US, for example, the average trip in a private car is less than 16 kilometres. Three-quarters of commuters in the UK drive less than 32 kilometres a day. These drivers could save hundreds of dollars a year if they switched to all-electric cars.

That's the thinking behind the Aptera, an electric two-seater car that looks like something out of The Jetsons and is due to go on sale in California later this year. Its radical design minimises air resistance, right down to little touches such as tucking the windscreen wipers below the airflow. As a result, the entire vehicle has a drag coefficient of just 0.15 - making its drag roughly the same as that caused by a single large wing mirror. It weighs only 680 kilograms, about the same as a Smart car. The Aptera's Li-ion battery may only hold 10 kilowatt-hours of electricity, but that's enough to give it a respectable 190-kilometre range and a top speed of 136 kilometres per hour. That is probably good enough for many commuters, especially if drivers are able top up their car batteries while they shop or eat.

On-street electric charging points are already being tested in San Jose and other US cities. In the Netherlands, electric utility company Essent and the start-up Electric Cars Europe, are also developing a plan for installing charge points across the country.

Perhaps the most ambitious recharging scheme comes from the Californian start-up Better Place. Launched in 2007, the company is collaborating with the Renault-Nissan Alliance in a bid to mass-produce Li-ion electric cars and build the recharging infrastructure needed to make the vehicles attractive to drivers. The company plans to launch the service in Israel and Denmark first - both ideal starting points as each country's major population centres are confined to an area around 150 kilometres across. In Israel, for example, Better Place aims to have the cars in showrooms and half a million charging stations installed by 2011. The stations will be in malls, parking lots and other public places. If a car runs out of juice, rather than wait for it to recharge at a charging point, the driver would pull in to a refuelling station where a machine automatically removes the battery and replaces it with a charged one, all in around the time it takes to fill the fuel tank on a conventional car.

If all that sounds like another quagmire where a lack of infrastructure will slam the brakes on development, GM says it has an interim solution. The firm's upcoming electric vehicle, the Chevy Volt, will use a Li-ion battery to propel the car from 0 to 100 km/h in under 9 seconds, and up to a maximum speed of 160 km/h. When the battery is running low, a petrol motor kicks in, but not to drive the wheels; the motor only charges the battery. That means the experience of driving will always be like driving an electric vehicle, but with the added benefit of being able to recharge on the go rather than having to plug in and wait for hours. GM claims this will push the range of the Volt up to a very useful 575 kilometres. When gasoline is being burned to charge the battery, it runs with a fuel efficiency of around 4.8 l/100 km. Because the Volt can be plugged into mains electricity for recharging, most short journeys will run on electricity alone. No wonder some people are hailing it as a "Prius killer".

Whether GM can deliver on its promise remains to be seen. The company wants to launch the car in 2010, but the cost of the Li-ion batteries may bump the price up to around $40,000, hampering its mass-market prospects. The company is not revealing much about its investment in the project, but says it has 700 staff working full-time on it. "This is definitely not a niche product," says Rob Peterson, a GM spokesman. "It's the number one priority for the company."

Back in the Tesla, a few kilometres down the road, a man on the sidewalk turns and stares as we cruise quietly past. Then his face lights up in recognition: "Hey! It's the Tesla!" It seems that, in this corner of California, Musk has already made electric cars sexy. Now it's just the rest of the world that needs to be convinced.

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