According to reports, you may not have a hydrogen gas filling station near your home anytime soon since there are less than 300 of them worldwide, most of which are in the US and Europe. However, that’s no reason why one should not celebrate the development of India’s first hydrogen-powered automobile bus by Tata Motors Ltd. and the Indian Space Research Organisation (Isro) after several years of research.
The hydrogen-fueled bus was demonstrated at the Liquid Propulsion Systems Centre, an Isro facility in Mahendragiri in Tamil Nadu on 30 July, according to a 28 July Press Trust of India (PTI) report. Hydrogen, bottled at high pressure, is stored on the top of the bus, the report said, adding the hydrogen cells were a spin-off of the cryogenic technology that Isro had been developing for the last few years.
Cryogenics relates to the study of very low temperatures. To store hydrogen in liquid form, it must be cooled to -423 °F. The concept of having hydrogen-powered cars is not new. What is heartening, though, is that the idea is coming close to becoming a production reality.
On 28 January, Ford, Renault-Nissan, and Daimler said they will jointly develop technology to make “affordable, mass-market” fuel cell vehicles by 2017, investing equal amounts into the effort. A week before this announcement, BMW and Toyota announced a similar joint development deal. Toyota says it will unveil a hydrogen fuel-cell-powered sedan later this year that will go on sale in 2015. In 2012, Hyundai (the ix35) and Honda said they were committed to fuel cell-driven vehicles.
Besides the obvious reason of the world running out of fossil fuels, the move to develop fuel cell-driven vehicles are also the result of a push from governments. For instance, in 2003, President George Bush announced the Hydrogen Fuel Initiative (HFI) to develop hydrogen, fuel cell and infrastructure technologies to make fuel-cell vehicles practical and cost-effective by 2020. The US has committed more than $1 billion to fuel cell research and development so far. And fuel cell technology is part of China’s 12th Five-Year plan.
For decades, NASA has relied upon hydrogen gas as rocket fuel to deliver crew and cargo to space. With the Centaur, Apollo and space shuttle vehicles, NASA has developed extensive experience in the safe and effective handling of hydrogen. Hydrogen is the lightest element, yet it has the highest energy content per unit weight of all fuels. Its energy density (at 52,000 Btu/lb) is three times greater than that of petrol.
Hydrogen is seldom found on its own in nature. It typically combines with oxygen and carbon. Hydrogen can be extracted from virtually any hydrogen-containing compound, including both renewable and non-renewable resources. Regardless of the fuel source, fuel cells utilize hydrogen with little to no polluting emissions, making hydrogen the ultimate clean energy carrier.
A fuel cell is an electrochemical device that combines hydrogen and oxygen to produce electricity. Fuel cell vehicles use a completely different propulsion system than conventional vehicles that can be two to three times more efficient. The vast majority of today’s hydrogen is produced via steam reformation of natural gas (95% in the US, roughly 48% globally), but alternative sources such as biogas are growing in popularity.
Hydrocarbon fuels–methanol, ethanol, natural gas, petroleum distillates, liquid propane, and gasified coal–can yield hydrogen in a process called reforming. Water electrolysis is another method. When an electric current is introduced into water, hydrogen and oxygen are separated, with hydrogen forming at the cathode and oxygen forming at the anode. Electricity can be provided from any source, but using solar and wind energy to electrolyze water provides the cleanest pathway to produce hydrogen. This model is being used in some hydrogen refueling stations and in renewable energy storage systems that utilize hydrogen.
Like all-electric vehicles, fuel cell vehicles use electricity to power motors located near the vehicle’s wheels. In contrast to electric vehicles, fuel cell vehicles produce their primary electricity using a fuel cell powered by hydrogen.
The most common type of fuel cell for vehicle applications is the polymer electrolyte membrane (PEM). Other fuel cells include the solid oxide fuel cell (SOFC), the alkaline fuel cell (AFC), the molten-carbonate fuel cell (MCFC), the phosphoric-acid fuel cell (PAFC) and the direct-methanol fuel cell (DMFC)–not all of which are suitable for cars.
Fuel cell vehicles fueled with pure hydrogen emit no pollutants, only water and heat. Vehicles that use secondary fuels and a reformer produce only small amounts of air pollutants. However, creating an infrastructure for hydrogen distribution and delivery to thousands of individual fueling stations presents many challenges.
Because hydrogen contains less energy per unit volume than petrol/diesel, transporting, storing, and delivering it to the point of end-use is more expensive. Hydrogen can be stored as either a liquid or a gas. To store hydrogen in liquid form, hydrogen must be cooled to -423 °F, requiring a tremendous amount of energy. Therefore, hydrogen produced in large quantities is usually pressurized as a gas then stored in caverns, gas fields, or mines before being piped to the consumer as natural gas is today, although storage technologies too are improving with time.