Fuel cells for automobiles
Shirish Joshi

Metallic Power, a fuel cell developer in the USA, has tested the world’s first on-road refuelable zinc air fuel cell (ZAFC) powered car successfully.

In addition to demonstrating the viability of the concept, the company showed that the robust simplicity of its proprietary regenerative ZAFCs could lead to more rapid development of products based on their technology.

The demonstration included more than 160 km of test-driving on highways and streets over various terrains in humid as well as dry, hot areas.

For the demonstration, four ZAFC systems were fitted into an electric car. The test crew drove the vehicle at speeds reaching more than 80 kmph and then quickly refueled it in approximately 30 minutes using simple fuel hoses that can make the process as simple as filling petrol or diesel.

A set of small lead-acid batteries connected in parallel with the fuel cells provided extra power for short bursts of acceleration and hill climbing, while the fuel cells supplied the bulk of the energy for long-range driving.

The technology holds promise of delivering as much as five times the energy of the same weight of lead-acid batteries. Such a vehicle could ultimately provide two to three times the range capability of a typical battery-powered electric vehicle.

This could someday enable zero-emission vehicles, with ranges of about 500 km, which consumers could safely refuel in a few minutes.

In a typical FAZC, there is at least a permeable membrane, a zinc anode separated by electrolyte, and some form of mechanical separators. The permeable membrane allows atmospheric oxygen to pass through.

After the oxygen has converted into hydroxyl (OH) ions and water, the hydroxyl ions will travel through an electrolyte, and reach the zinc anode. Here, they react with the zinc, and form zinc oxide, a common white powder found in skin creams.

This process creates electricity. When a set of ZAFC cells are connected, the combined electricity potential of these cells can be considerable, which could then be used as a source of electricity to drive the motors connected to wheels.

Metallic Power’s ZAFCs are fueled with small zinc pellets. As this fuel is consumed inside the fuel cell, it is combined with oxygen from the air to form zinc oxide.

During refueling, the zinc oxide — which remains dissolved in the liquid electrolyte — is pumped out of the vehicle, while fresh pellets are introduced and electrolyte is pumped back in. The zinc oxide and spent electrolyte can be completely regenerated back into fresh zinc pellets and electrolyte in a separate, stationary device also under development by the company.

It is a completely closed-loop system. There’s nothing added nothing wasted, and nothing to throw away or pollute the environment.

A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into electricity and heat. It is very much like a lead-acid or nickle-cadmium rechargeable battery that can be recharged repeatedly. Instead of recharging using electricity, however, a fuel cell uses hydrogen and oxygen. A ZAFC uses zinc metal instead of hydrogen.

Air pollution changes rainfall

Nearly two decades after one of the world’s most devastating famines in Africa, scientists are pointing a finger at pollution from industrial nations as one of the possible causes.

The starvation brought on by the 1970-85 drought that stretched from Senegal to Ethiopia captured the world’s attention with searing images: skeletal mothers staring vacantly, children with bloated bellies lying in the sand, vultures lurking nearby. Before rains finally returned, 1.2 million people had died.

Now, a group of scientists in Australia and Canada say that drought may have been triggered by tiny particles of sulfur dioxide spewed by factories and power plants thousands of miles away in North America, Europe and Asia.

The short-lived pollution particles, known as aerosols, didn’t have to travel to Africa to do their dirty work. Instead, they were able to alter the physics of cloud formation miles away and reduce rainfall in Africa as much as 50 per cent, say the researchers, who used a computer to simulate the atmospheric conditions.

The process, known as teleconnection, continues in the atmosphere today. Some scientists suspect it might help explain the drought gripping parts of the USA, although that question has not been specifically examined.

And while pollution may affect the behaviour of rain clouds, scientists stopped short of solely blaming industry’s effluent for the famine and starvation that wracked the region of Africa called the Sahel.

“It’s more subtle than that,’’ said scientist Leon Rotstayn, lead author of the study on the subject.

“The Sahelian drought may be due to a combination of natural variability and atmospheric aerosols,’’ said Rotstayn, of the Commonwealth Scientific and Industrial Research Organization, a government research agency in Australia. The CSIRO study will be published in the August Journal of Climate.

Over the years, the disastrous lack of rainfall over the Sahel has been blamed on everything from overgrazing to El Nino. Many scientists still argue those are chief culprits.

One interesting clue: In the 1990s, rain returned to the Sahel. During the same period, emissions laws in the industrialized West reduced aerosol pollution. A coincidence? Scientists don’t think so.

“Cleaner air in the future will mean greater rainfall in the region,’’ Rotstayn said.

Some researchers say the CSIRO study is intriguing, but that the computer simulation is too simple to solve the mystery by itself. AP 

Human gene combats HIV

Scientists in Britain and the USA say they have found a unique gene in humans that defends the body from AIDS virus, a discovery that could open up a new front to fight the disease.

The gene, called CEM15, is able to halt infection by the human immunodeficiency virus, but is usually switched off by a small HIV protein called Vif, they report in a lab study.

When Vif was stripped out of the virus, CEM15 disrupted HIV’s replication, rendering any new virus particles non-infectious, they say.

The study, published online by the British medical journal Nature, was led by Michael Malim, a professor at King’s College London, and Ann Sheehy and others at the University of Pennsylvania School of Medicine.

“These are very significant findings and could open the door to new treatments for HIV/AIDS in the future,” King’s College quoted Malim as saying.

“(...) If we can find a way to block the action of Vif it would allow CEM to work properly and prevent HIV from spreading.”

Around 40 million people around the world have HIV, according to the UN agency UNAIDS. AIDS, the fatal destruction of the immune system caused by HIV, has already claimed 20 million lives in little more than two decades.

Malim cautioned that a lot remained to be learnt about Vif, but it stood a chance of becoming a new treatment to fighting HIV in the next 10 years.

“If we can find a way to block the action of Vif, it would allow CEM15 to work properly and prevent HIV from spreading,” he said. AFP

Light from gas bubbles

A gas bubble excited by ultrasound turns a tiny fraction of the sound energy into light. This phenomenon called sonoluminescence has been observed for decades.

Now, chemists supported by the National Science Foundation have, for the first time, measured the chemical reactions and light emission from a single water bubble excited by sound waves. The researchers, Ken Suslick and Yuri Didenko of the University of Illinois, said in their findings published in the July 25 ‘Nature’.

Ultrasound applied to a liquid causes the formation, growth, compression and collapse of microscopic bubbles in a process called cavitation. These small oscillations can cause intense heat and pressure, similar to the conditions produced on a large scale by explosions or shock waves. This excitation also can cause emission of short flashes of light.

The ability of ultrasound to induce high-energy chemical reactions has been studied for potential industrial and medical applications, such as the breakdown of pollutants and development of medical imaging agents. To harness this process, however, scientists needed to quantify the energy and molecular particles released within a single, isolated bubble.

The Illinois experiment showed that, as pulsating water bubbles collapse, they create temperatures high enough to break water molecules apart.

Less than one millionth of the sound energy is converted into light. A thousand times more energy goes into the formation of atoms, molecular fragments and ions. The largest part of the sonic energy is converted into mechanical energy, causing shock waves and motion in the liquid surrounding the gas bubble.

“Cavitation, which drives the implosive collapse of these bubbles, creates temperatues resembling those at the surface of the sun and pressures like those at the bottom of the ocean,” the scientists said. “This phenomenon offers a means of concentrating the diffuse energy of sound into a chemically useful form”.

Possible applications include making catalysts to clean fuels, removing sulphur from gasoline and enhancing the chemical reactions used to make pharmaceuticals. The process has already been used to make new chemical catalysts for industrial use and biomedical agents for magnetic resonance imaging. PTI

NEW PRODUCTS & DISCOVERIES

Frame connected with internet

Taking its cue from the outrageously overpriced Sony CyberFrame, a start-up by the name of Ceiva Logic in West Hollywood, California, has gone one better with its innovative Internet appliance device named the Ceiva Internet Connected Digital Picture Frame. By simply plugging the picture frame into a standard electrical outlet and a telephone jack, the Ceiva turns into an “online” display device that can receive digital photos which have been uploaded to the Ceiva website.

There is no keyboard, no mouse or a PC connection… just two buttons on the back of the picture frame which adjust display brightness, allow for switching between either displaying a single image or cycling through a collection of multiple images, and control manual photo downloads.

To activate the Ceiva frame, an online account is set up which includes a user name, password and a “Buddy List”, which tells Ceiva from whom it can receive digital images. Authorised senders can then forward and upload their digital photos to the Ceiva website; the frame does the rest of the work by automatically calling a local access telephone number in the middle of the night, typically between the hours of 1:00 a.m. and 5:00 a.m., to retrieve any new pictures which have been posted to your account.

Located within the Ceiva picture frame is a microprocessor which directs the collection and display of the images, along with a one MB flash memory card which holds approximately 10 photo images. When the Ceiva frame dials up the local access number in the middle of the night, it will remove existing images on a one-for-one first-in/first-out basis to download any new photos which have been posted to your account. Purged photos will be stored back on your account at the Ceiva website. There is also a feature which allows you to lock images onto your picture frame and not have them replaced by newer images, if so desired. The download process takes about 4-5 minutes to complete a full 10 photo download and your connected telephone line is obviously unavailable during this short time window.

A manual download, during the middle of the day, can be initiated by pressing and holding the white control button on the back of the picture frame. Because the frame incorporates flash memory, it can be disconnected from an AC electrical outlet and moved to a new location without loss of the last set of images displayed on the unit. Price: $249

Sheep gene chase

Australian scientists have begun work on a $ 8.1 million project to track down the gene that produces the meatiest lamb chops.

The sheep genomics project, which will study what sheep genes do and identify gene markers for desired characteristics, will also have the potential to identify parasite-resistant sheep, better disease tests and controls and deliver meatier lambs.

Funded by A$3 million a year in producer levies and matching federal government money, the five-year project is expected to produce the first full map of the sheep genome.

“The potential return to industry from basic research in this area of functional genomics is enormous,’’ Meat & Livestock Australia’s southern production research manager Hutton Oddy said in a statement. Reuters

SCIENCE & TECHNOLOGY CROSSWORD

Clues

Across :

1. Scientist by whose name the rules to simplify complex circuits are known.

9. Optical counterpart of an object.

10. Curved structure acting as a bridge or lintel over an opening.

11. Abbr. for Spectrometers doing surface composition analysis and depth profiling.

12. An alloy whose melting point is lower than that of any other alloy of same ingredients.

14. Main body or stalk of a plant.

17. Symbol for Tellurium.

18. …..bean, large flat seed of edible bean.

19. Most accurate measurement of time based on a time scale derived from the vibrations of atoms. (abbr.)

20. Sensations produced in eye by rays of light when resolved by prism.

23. SI Unit of solid angle.

Down :

1. Science of rest or motion.

2. Product of a force and the short duration for which it acts.

3. A pattern of scanning lines covering the area of projection in cathode ray tube of TV set.

4. Abbr. for Centre of Gravity.

5. An HP Corporation making electronic gadgets and based in Chambaghat.

6. A fertile spot in desert.

7. An effect that opposes the motion of one surface over the other.

8. A monitor that determines the particle contamination of liquids (Abbr.)

13. Great circle of the earth equidistant from the poles.

15. An Interferometer used to study the fine spectrum lines based on interference effects.

16. A device used for internet connections.

18. Feathered vertebrate.

19. A beer type substance.

21. Short for a famous airline formed by merger of 4 airlines.

22. Abbr. for computer based facility for instant interpretation of speeches and messages.

Solution to last week’s Crossword: