Low-tech Magazine

Gas Bag Vehicles

Wood gas cars were not the only answer to the limited supply of gasoline in World War One and Two. An even more cumbersome alternative came in the form of the gas bag vehicle.

The old-timers on these pictures are not moving furniture or an oversized load. What can be seen on the roof is the fuel tank of the vehicle - a balloon filled with uncompressed gas.

Wood gas vehicles: firewood in the fuel tank

During the Second World War, almost every motorised vehicle in continental Europe was converted to use firewood.

Wood gas cars (also known as producer gas cars) are a not-so-elegant but surprisingly efficient and ecological alternative to their petrol (gasoline) cousins, whilst their range is comparable to that of electric cars.

Rising fuel prices and global warming have caused renewed interest in this almost-forgotten technology: worldwide, dozens of handymen drive around in their home-made woodmobiles.

Cars: out of the way

Some readers have observed that we haven't paid any attention to one of the most low-tech innovations ever - the humble bicycle. We noted the sex-appeal of pedal power (and this concerns both men and women), but that's about it. So, since you asked for it, here is our concise but clear point of view on these human powered two-wheelers.

Who killed the electric grid? Fast-charging electric cars

Charging electric cars with off-peak power is a fantasy.

Fast recharging times generate lots of excitement, but what seems to be forgotten is that they can lead to a fabulous amount of peak demand.

If you charge an electric car with a battery capacity of 25 kWh during 8 hours, it needs a power output of 3,125 watts. If you charge the same car in just 10 minutes, it needs a power output of 155,000 watts.

The age of speed: how to reduce global fuel consumption by 75 percent

If we cut the average speed of all vehicles by half, fuel consumption would decrease by a whopping 75 percent.

Breaking speed records was an almost daily occurence throughout the 20th century. Cars, ships, planes and trains became faster and faster, year after year. Because the power needed to push an object through air increases with the cube of velocity, this race to ever higher speeds raises energy consumption exponentially.

Engineers treat velocity as a non-variable, while in fact it is the most powerful factor to save a really huge amount of energy - with just one stroke, at minimal cost, and without the need for new technology. Lower speeds combined with more energy efficient engines, better aerodynamics and lighter materials could make fuel savings even larger.                                                                     Picture : Mando Maniac

The Citroen 2CV: cleantech from the 1940s

If you sometimes wonder why more energy efficient technology does not bring about more energy efficient cars, you should take a look at this collection of Citroën brochures (most of them in foreign languages) from the fifties, the sixties, the seventies and the eighties (more here, here, here and  here).

These are all original, scanned leaflets of the legendary French hippie car "2CV" or "Deux Chevaux" (known as the "duck" or the "goat" in several European countries). In spite of all the high-tech that has been squeezed into cars since then, the 2CV from 1949 is still more energy efficient than the smallest model of the French car designer today. Why?

Why the electric car has no (wireless) future

The electric car is not a technology of the future, but from the past.

The electric car is 170 years old. This may sound surprising, but e-cars predate automobiles with a combustion engine. They were driven out of the market in the beginning of the 20th century because petrol engines had significantly better mileage. One century later, the electric car still faces the same – fundamental – problems. Furthermore, the need for batteries makes them eco-unfriendly by nature. The only possible green future for electric cars is a wired future: hooked up to the overhead lines, like trolleybuses and bumper cars.

Cars on hot air

Following the hype on hydrogen - meet the car on compressed air.

A small car that runs on compressed air is making headlines around the world. The design is a concept from the French engineer Guy Negre, and the Indian car manufacturer Tata Motors is the first to start production of the new vehicle.

If we can believe the news, the zero-emission car has finally arrived. No more pollution, no more CO2. “Amazingly this car is powered by air”, said the BBC in a commentary: “It sounds too good to be true”. In fact, it is too good to be true.

Solar powered cars

If racing cars can drive on solar energy, then why do normal cars still need fossil fuels?

Around 30 cars race 3,000 kilometres across the Australian continent in the “World Solar Challenge”. Solar cars are electric vehicles that generate their own electricity, by means of around 6 m² of solar panels installed on their bodywork, and a series of linked up batteries that serve as a fuel tank. If we want the car to survive in the longer term, it should become slower and lighter again, trimmed to the efficiency of solar panels and batteries. (Picture: Venturi Astrolab)