SCIENCE & TECHNOLOGY Thursday, September 4, 2003, Chandigarh, India
 

Developing hydrogen as an energy source
Radhakrishna Rao
F
OR many years now, energy experts have been driving home the point that hydrogen, the most common and abundantly found element in the atmosphere, could very well serve as a clean energy sources for the vehicles currently running on pollution causing fossil fuel. But then the logic of transition to hydrogen, considered the simplest and cleanest fuel, has been argued in length for more than a century now.

PROF YASH PALUNDERSTANDING THE UNIVERSE
 WITH PROF YASH PAL
W
HAT are the factors that can cause a change in the mass of the earth and how can we measure this change? 
There must have been several phases in the life our planet when its mass changed. The earth was probably formed through accretion of lot of dust and gas, and accumulation of lot of asteroid seized objects.

NEW PRODUCTS & DISCOVERIES

Top









 

Developing hydrogen as an energy source
Radhakrishna Rao

Toyota Hybrid highlander
Toyota Hybrid highlander

FOR many years now, energy experts have been driving home the point that hydrogen, the most common and abundantly found element in the atmosphere, could very well serve as a clean energy sources for the vehicles currently running on pollution causing fossil fuel. But then the logic of transition to hydrogen, considered the simplest and cleanest fuel, has been argued in length for more than a century now.

In fact, as early as in 1870, Jules Verne had written that hydrogen would be a good substitute for coal.

At the moment, researchers around the world are busy devising ways and means to make hydrogen fuel available to motorists from the familiar petrol pumps. All said and done, serious development of hydrogen based energy system awaits the development of fuel cells that are economically viable. As envisaged now, the hydrogen for those initial fuel cells would probably be derived from natural gas since splitting water through electrolysis is far more expensive at the current level of technological development. This would allow a hydrogen pipeline system to be built up gradually, piggybacking on the natural gas system already in place.

Taiwanese scooter
Taiwanese scooter

Scientists at the Warwick Process Technology Group in the United Kingdom are of view that hydrogen, an ultra pure gas, has the potential to prove far cheaper than the currently used fuels for internal combustion engines. Their new project named ďHydrofuelerĒ focuses on developing equipment that will ensure a ready source of fuel not only for engines of the vehicles but also for the fuel cells of the future.

ďIf the hydrogen is to be a realistic option and a fully practical replacement for present day fuel for road vehicles, it will have to become readily available to everyoneĒ says Dr Ashok Bhattacharya, Director of the Warwick Process Technology Group. As things stand now, the big hurdle in scaling down industrial hydrogen plant, says Dr Bhattacharya, is the relative inefficiency of their production process. Building a conventional plant small enough to blend into the neighbourhood would send the cost of hydrogen sky high and fuel could never be produced at the rates demanded.

Against this backdrop the Warwick team is developing and blending existing and new technologies to create a hydrogen producing reactor small enough to fit into the filling stations and big enough to supply large amounts of high quality hydrogen and safe enough to meet the most stringent regulatory and environmental standards. ďWe are aiming to produce a couple of systems about the size of three office decks that can be used in available space in filling stations to produce hydrogen cost effectively and without any emissionĒ.
Thunderpower bus
Thunderpower bus

The process is based on highly active catalysts that can be coated on to the plates of the reactor with ultra high levels of mechanical and thermal stability. The Warwick Process Technology Group has developed such catalysts and also the technology to produce them. The Warwick team and its partners are also forging ahead with the development of a compact hydrogen separation unit that can deal with very high rates of gas production. Meanwhile, a study by Laboratory for Energy and Environment of the Massachussets Institute of Technology (MIT) says that hydrogen fuel driven vehicles need not be better than fossil fuel driven vehicles. Adoption of the hydrogen based vehicles will require major infrastructural changes to make compressed hydrogen available.

In fact, energy experts have been telling that hydrogen can be mixed with natural gas and carried in the same pipeline, shifting alter to new pipelines that are designed to carry pure hydrogen. This would allow a relatively seamless transition. In the future, large amounts of hydrogen could be produced in remote wind farms, solar stations and ocean power plants and stored underground. Homes could produce some of their own hydrogen using rooftop solar cells, storing it in basements.

A new project funded by Americaís National Aeronautics and Space Administration (NASA) is helping to tackle some of the hurdles in the way of generating hydrogen energy. As it is, astronauts have been using hydrogen for power generation aboard spaceships since 1960s.

Top

UNDERSTANDING THE UNIVERSE
WITH PROF YASH PAL

WHAT are the factors that can cause a change in the mass of the earth and how can we measure this change?

There must have been several phases in the life our planet when its mass changed. The earth was probably formed through accretion of lot of dust and gas, and accumulation of lot of asteroid seized objects. So the mass was built up, not provided at the very beginning. The mass exchange must have included collisions with comments and meteorites, resulting in some gain and some loss. It is believed, for example, that the water on the earth might have come from comet bombardment in the early phase of the solar system. We have another evidence of the mass change ó this lies in the very existence of the moon.

The generally accepted hypothesis for the earth acquiring such a large satellite is that the moon was formed in collision of a planet-like body with the earth. This is supported by the fact that the chemical constitution of the moon is rather similar to the outer part of the earth. The object that collided might also have left its debris. A significant change in mass of the earth in an event like this is very likely.

I might also refer to the escape of several light gases. Most of the hydrogen in the atmosphere has certainly escaped. The thermal velocity of hydrogen molecules even at high altitude is higher than escape velocity from the earth ó the earth is not big enough to restrain this light gas by its gravitational force. Helium also has a similar freedom.

Now we come to the second part of your question: how can we find out if the earth has been losing or gaining mass? Indeed, how do we measure the mass of the earth or any other heavenly body? Do we have an appropriate balance for this purpose? It turns out that we do.

If we launch a satellite and put it in a circular orbit a few hundred kilometres above the earth, it takes about 90 minutes to go around. The distance of this satellite from the centre of the earth is a little more than 6,400 kilometres, the radius of the earth. If the distance of the orbit is about 42,000 kilometres then the satellite would take 24 hours to go around.

At the distance of the moon we know that the time is nearly 27 days. There are not empirically determined separate facts. Their relationship depends on the assumption that the mass of the earth and the force of gravity are the determinant parameters.

If you put these numbers in Newtonís equations, you will get the mass of the earth. Any high school student can measure it to an accuracy that would be satisfactory. Notice that we are making use of the conviction that, in spite of all the hocus pocus about astrology, the earth and all the planets behave as they should, without bias, without anger and without malice.

This is precisely how all the masses of the heavenly bodies are estimated. This applies to all the planets, the sun, and the galaxies, even neutron stars and black holes.

Coming back now to your original query: can we actually measure the change in mass of the earth-say year to year? It would seem that a year, even our lifetime, might be too short a time for getting a significant change. But I may be wrong. For example, recently, using extremely accurate timing, it has been found that the angular velocity of rotation of the earth is modulated on a seasonal basis.

This is believed to be due to the increase and decrease of biomass over the earth ó there is greater biomass during the northern summer because of uneven distribution of landmass between the two hemispheres. What is conserved is the angular momentum; change in the angular velocity is due to the change of moment of inertia, which depends on the change in mass.
Top


Home

NEW PRODUCTS & DISCOVERIES

Record amount of stellar debris

DUST COLLECTOR. Artistís view of the Ulysses spacecraft, which has flown over the sunís poles.
DUST COLLECTOR. Artistís view of the Ulysses spacecraft, which has flown over the sunís poles.

INTRUDER alert! Stardust is sneaking into our solar system at three times the rate that it was just six years ago. Moreover, the influx of dust could triple again by the end of 2010.

These findings are based on the latest measurements by the Ulysses spacecraft, launched in 1990 to become the first observatory to explore the sunís poles. Before Ulyssesí tour, which takes it from Jupiterís neighbourhood to far above the solar poles, most astronomers didnít think much dust from other stars could penetrate the solar system. Sunlight rapidly charges dust attempting to enter the solar system, and, according to conventional theory, the sunís magnetic field then ejects the particles.

But in 1993, the space probe found that some particles barrel through the sunís magnetic shield. During solar maximum, when activity on the sun is most intense, even more stardust penetrates. Thatís because the sunís magnetic field begins flipping polarity, and the disordered field canít efficiently deflect dust particles.

Yet even though solar maximum ended in 2001, the rate at which stardust enters the solar system has remained high, report Markus Landgraf of the European Space Agency in Darmstadt, Germany, and his colleagues in the October Journal of Geophysical Research.

The explanation lies in the gradual way that the magnetic field changes polarity, Landgraf says. The field is now pointing nearly sideways, with its north and south magnetic poles lying along the sunís equator. In this configuration, the direction of the magnetic field rotates along with the sun every 28 days. Because the dust takes several months to react to the magnetic field, it experiences an average magnetic force of nearly zero. As a result, the magnetic field is now ineffective as a gatekeeper.

Plastics in food packaging

The primary concern in food packaging is that the package does not adulterate the food in some way that could be harmful to the consumer. Thus the main concern is migration of constituents from the packaging material to the food in contact with it. But there are also other factors like appearance, chemical compatibility, physical endurance, and shelf life. To guarantee the shelf life of a product, the packaging material must offer good seal integrity, moisture barrier, oxygen barrier, light barrier, and aroma or odour protection.

Unhygienic food processing and improper packaging can create hazards like salmonella, microbes, endotoxins, migration of toxins from packing material, adhesive and inks and can render the food unfit for human consumption. Even after following proper processing practices, one has to ensure that packaging is designed properly for a particular food with the specified shelf life. This is where plastics have proved most useful in packaging. Barrier plastic film enables aseptic packaging of food, preventing a lot of wastage and reducing the need for refrigerators. Flexible plastic packaging for milk and edible oils eliminates the use of tin and glass, as do PET bottles for safe drinking water.

Rigid HDPE barrels for bulk chemical storage replace steel drums. This packaging, being light in weight, saves on transportation costs.

Top