Fossil fuel used in transportation causes over 2000 million tonnes of CO2 emissions each year. Some 75 million new cars are produced each year, adding to these emissions. Hydrogen is the attractive alternative fuel for cars, producing no CO2. So far, the hydrogen gas needed to be either liquefied to cryogenic temperatures or compressed to high pressures. Both are energy intensive processes and need a completely new type of vehicle to be designed. A new development announced by Cella Energy of UK promises a technology to deliver hydrogen from a kerb-side pump into a regular fuel tank. If this new technology pans out, it could be the transformation needed for rapid acceptance of hydrogen powered cars.
The Cella Energy technology
Cella Energy is a technology company, that has spun out from the UK Science & Technology Facilities Council’s Rutherford Appleton Labs. They have developed a process to trap amonia-borane hydride inside tiny porous polymer beads. The beads, made with nano-technology, are 30 times smaller than the human hair.This structure protects the hydrides from contact with air and overcomes the issue of spontaneous combustion, which has been one of the problems with the use of hydrides.
Since the beads are so small, they can be poured or pumped like a fluid. This makes it possible to handle the Hydrogen-Petrol fuel with the same tanks, pumps and pipelines, that are today used for petroleum based fuels. Since hydrogen has 3 times the energy content of petrol (for the same weight), a full tank of the synthetic fuel will run the car for 300 to 400 miles.This does away with the range-anxiety issue that has plagued electric cars.
The spent beads can be recharged with hydrogen and reused, making the process additionally attractive. This recycling will, of course, need a modification to the cars to be able to be able to discharge the spent beads from the fuel tank. The cost of this synthetic fuel is estimated to be only some one-fourth to one-fifth of gasoline. In the UK, the researchers say the cost would be 19 pence a liter. This should be the added attraction in quick acceptance of this new fuel.
The benefits of this new technology are obvious. The Hydrogen-Petrol is pumped like the conventional fuel, cost a lot less and the car engine needs no modifications. One of the concerns with alternative fuels technology has always been the cost of converting existing vehicles. This synthetic fuel could be readily used in existing cars. Cella Energy has also said that even a 20% addition of this synthetic fuel as a blend with petrol, reduces CO2 emissions. As with ethanol blends, this could be an intermediate step in the transition to this fuel.
Hydrogen is only an energy carrier, like electricity. It is not an energy source as petroleum fuels are. In other words, hydrogen gas has to be produced separately, to be charged into the ammonia-boron-hydride beads. The hydrogen production process is very energy intensive. The most common method is hydrolysis of water, which is especially energy intensive.The alternatives are to use hydrogen that is produced as a by-product, for example in the steam reforming of natural gas or from landfills or biomass plants. Until new technologies emerge for hydrogen production with lower energy usage, wide spread application of hydrogen as fuel could be delayed.
The recharging of spent beads with hydrogen is another problem that needs further work. The polymer bead that protects the hydride also acts as a barrier to hydrogen recharge. Cella Energy already acknowledges this problem and is working on alternative materials. Some skeptics also think that the synthetic fuel costs would go up, once governments begin to tax this fuel, as they do, the other forms of energy.
The storage of hydrogen in a form which can be handled like the conventional fuel is the major impact of this technology. The additional attraction is that the car engines need no modifications. The low cost is additional icing on the cake. The use of hydrogen in transport vehicles would make a significant impact not just on greenhouse gas emissions, but also on the sulfurous oxides and particulates that pollute city atmospheres.