Hydrogen shows promise in vehicle tests
(chinadaily.com.cn)
Updated: 2004-06-01 14:01

Car fleets escorted by police along Chang'an Avenue are not a rare sight for Beijing residents, who are accustomed to the practice when leaders of foreign states visit the capital of China.

Yet when the police motorcycles sped along the avenue to the Great Hall of the People in drizzle last Wednesday, they were not escorting such dignitaries, but two buses.

At first glance, the vehicles that started off from the Kempinski Hotel looked little different from those travelling around the city. The inside of the vehicles, however, had been totally revamped.

The buses had no gasoline engines. They were running on fuel cells powered by hydrogen, rather than gasoline, and emitted no polluting exhaust fumes.

Watched by experts, government officials and the press, the buses carried not only scores of invited passengers, but a dream that Chinese scientists hope will be the answer to the looming energy crisis and ever-increasing air pollution worldwide.

At the destination of the bus tour, the Great Hall of the People, scientists, government officials and business leaders from around the world gathered to discuss the prospects of a future energy resource: hydrogen.

Clean energy source

As an alternative energy source, hydrogen is clean, efficient and largely renewable, compared with fossil fuels such as oil and coal. It's no surprise that people have long dreamed of the day when hydrogen can supplant fossil fuels as the primary power source.

International concern about hydrogen economy mounted recently, when international oil prices hit a 21-year high.

"Everybody is talking about the energy shortage nowadays, not only in China, but internationally," said Bao Deyou, a hydrogen use researcher who attended the second international symposium on hydrogen energy in Beijing.

"When they look to alternative sources, hydrogen is invariably top of the list of candidates because of its unparallelled efficiency, cleanness and renewability."

Of many kinds of feasible applications of hydrogen energy proposed by scientists, the most practical, if not readily available, so far, are fuel cell vehicles, or FCVs.

A fuel cell is an electrochemical energy conversion device that converts hydrogen and oxygen into water, producing electricity and heat in the process.

It is very much like a battery that can be recharged while you are drawing power from it. Instead of recharging using electricity, however, a fuel cell uses hydrogen and oxygen.

The hydrogen-powered bus road show along the Chang'an Avenue serves as a good example.

One of the buses was made by the international automobile giant, Daimler Chrysler, and the other by a Chinese collaboration led by a team from Tsinghua University.

Despite their different technology, both are equipped with fuel cells and both makers are eyeing production for the 2008 Beijing Olympics. The Beijing local government has announced it would like to see the environment-friendly, hydrogen-fueled buses on the road for the great event.

The Daimler Chrysler bus will be trialled in Beijing in September next year at the earliest, for the first time in China. The auto company will provide three prototype model fuel cell buses for commercial runs in Beijing in three to four years. The contract involves international co-operation between the Chinese Government and the United States.The other bus was made by Tsinghua researchers who also participated in the bid and will likely vie for a second bid, according to Loris Yao from the Shen-Li High Tech Corporation in Shanghai. Shen-Li has also participated in the Tsinghua FCV programme.

His company also brought to the Beijing meeting their latest version of hydrogen fuel cells which have been fitted in a prototype. The silvery fuel cell car, named Transcend 2, is the first of its kind in China. The car, once fuelled, can travel 200 kilometres, at a speed of up to 106 kilometres per hour, Yao said.

Worldwide research and development on FCVs is in the fast lane, partly encouraged by technological advances as well as the pressure of energy shortages, he said.

At least 20 companies have developed more than 70 types of model FCVs so far, according to Wang Congwei, a Chinese researcher on FCVs.

He noted in a report that some international automotive giants have already set timetables for commercial production of FCVs. Daimler Chrysler, for instance, has already run fuel cell buses in several European countries on both trial and commercial bases.

"That may partly explain why they won the bid for the Beijing trial service," Yao from Shen-Li said. "They have some operational experience."

Car makers say they expect to release the next generation of FCVs in two or three years and market the vehicles by 2010.

From that time, FCVs will have to compete directly with gasoline-powered cars, in price, speed and comfort. It may be a tough war for FCVs, despite their pronounced advantages over gasoline fueled cars, said Wang, a researcher at the Guangzhou Institute of Energy Research.

At present, there are several different types of fuel cells, each using a different chemistry. Fuel cells are usually classified by the type of electrolyte they use. Some types of fuel cells show promise for use in power generating plants. Others may be useful for small portable applications or for powering cars.

The proton exchange membrane fuel cell (PEMFC) is one of the most promising technologies.

PEMFCs operate at a fairly low temperature, about 80 C, which means they warm up quickly and don't require expensive containment structures.

Constant improvements in the engineering and materials used in these cells have increased the power density to a level where a device about the size of a small piece of luggage can power a car.

Both the model buses on the road show in Beijing and the Transcend 2 car use this type of fuel cell, according to Yao.

Yet the cost of the PEMFCs remains a major hurdle, if not the only one, to its application. For instance, to make PEMFC, platinum has to be used, which would increase its cost tremendously.

"It is necessary to develop approaches that may reduce the use of platinum, hence the cost, by a hundred fold before the FCVs can start to compete with normal cars," Yao said.

Greater challenge

Yet the technological hurdles facing fuel cells are not the whole story. A steady, large-scale supply of hydrogen for FCVs may prove another, even greater challenge, said Yao.

At present, two basic approaches are being tested for supplying FCVs with hydrogen. One is to establish refueling stations, like gas stations.

Accordingly, a big infrastructure to manufacture and transport hydrogen will be necessary, which means huge investment that may turn out to be more than that for making FCVs, Yao said.

Another approach is to equip the FCVs with hydrogen-producing devices to avoid the need for refueling infrastructure.

Technologies have been developed to produce hydrogen through electrolysis or to convert methanol or natural gas into hydrogen through a process known as reforming.

Unfortunately, the reforming process is not perfect. It generates heat and produces other gases besides hydrogen.

Various devices have been used to clean hydrogen, but even so, it is not pure, and this lowers the efficiency of the fuel cell.

"Each approach is not perfect, so the research and development approach has to be drawn up by taking into account the particulars of each country's energy strategy and technological capacity," Wang noted in his report.

Safety is another concern that all types of hydrogen FCVs have to address. Unlike gasoline, hydrogen is volatile and inflammable. Gas leakage or collision may lead to disastrous consequences without reliable security design.

"That's why most of today's FCVs are still running on the test track," Yao said.

That's also part of the reason that the road show last week in Beijing was so carefully escorted by police, Yao said.

Despite pressure from the automobile industry, many researchers attending the Beijing meeting are taking a wait-and-see line, which Yao said is understandable given the complexity of the issue. He said a country's energy strategy may prove pivotal in pushing the research and development of FCVs ahead. "This technology is not for now or the next few years, it is for the next few decades and beyond," he said.