Using Solar Energy for Cooling

German and Bengali students and young professionals are doing research work in a special course of the Technical University's Energy Institute, before they will do field work in a rural health center in Bangladesh from August on. By Steffen Marquardt

"Solar heating and cooling in rural Bangladesh" is a project of a student exchange programme between Germany and Bangladesh. Its cooperation partners are the Renewable Energy Research Center of the University in Dhaka, the Bengali Center for Mass Education in Science and the Technical University of Berlin.

The Energieseminar at Berlin's Technical University has existed for more than 20 years now. It started as a reform project and it still represents the idea of an alternative way of studying in contrast to the usual procedure of professor-held lectures, says Dino Laufer of the institute:

"We very much focus on teamwork; that means we really work in teams. The team is scheduling the semester plan and is also taking over the moderation process, for example. They students are involved in the whole process. It's not only us, the teachers and professors, who give classical lectures. We emphasize that students as well should have the knowledge to teach each other."

Technology combined with social thinking

By working in interdisciplinary groups, the Energieseminar concentrates on combining technical projects concerning renewable energies with social thinking as it is required for social development in the global context, Dino Laufer explains.

"We think that very often the implementation of technology, also the renewable technology concerning renewable energy, is also a social process. It should be taken into consideration more frequently that not only the technology is a problem. Very often, the implementation of technology is a sensitive and sometimes difficult process, too."

For Wolfgang Lanser, the social aspect was a major reason to apply for the course. Renewable energies and micro-financing are the ideal combination for his further studies:

"I was a bit frustrated while studying business engineering. They always tell you about rationalizing and automation and at the same time you read in the newspapers about new highs in unemployment. So I thought solar cooling would be a possibility to work on in other countries later on and in combination with micro credits, to cover the economic part of my studies."

A poor country, but rich in solar energy

The Renewable Energy Research Center of the University of Dhaka and the Center for Mass Education and Science were very interested in research work for solar cooling and, therefore, asked Berlin's Technical University for cooperation. Bangladesh is a poor country, says Sheik Abdu Salim, who came from the CMES in Dhaka to Berlin, but that it has a lot of sun which should be used much more.

"Most of the people in the rural area do not have access to electricity. The THANA-Health complexes have connection, but most of the time they do not receive electricity for several reasons. So it would be convenient for the people to get technologies like solar thermal collectors or solar thermal photo-voltaics that preserve medicine."

Medical for remote areas

The students of the "Solar Cooling" project focus on two urgent topics in the health sector in Bangladesh's rural areas: on cooling boxes for medicine and vaccines and on air-conditioning in hospitals and small health centers with solar energy. The boxes are needed in order to bring, for example, vaccines to small villages that are far away from cities and difficult to reach.

However, vaccines have to be stored at a certain temperature ranging between 0 and 8 °C. Thus, a good and safe regulation of the cooling volume is needed, which a normal fridge can not guarantee. The second challenge is the solar equipment, because energy is also needed when the sun isn't shining.

That's why you need a good storage system, explains Wolfgang Wasserthal of another institute of Berlin's Technical University. He has already produced some cooling box prototypes.

"One can achieve this with a very good isolation. So we luckily found out a kind of vacuum isolation that is seven times as good a normal foam isolation. That means we need less energy to cool the same volume and the passive cooling time of the refrigerator is much longer than that of a normal fridge, which is important when you have no sun."

The disadvantage is that such systems are also much more expensive than normal fridges. The prototypes are still being tested, but now money and a partner are needed to convert them for mass production. Although cooling medicine and vaccines has priority, air-conditioning in health centers is more than a luxury as well, says Khalif Abdu Salim.

"The World Health Organisation has recommended 18 to 22 °C and humidity of 40 to 60 percent for air-conditioning. This is needed, when doctors work in surgery rooms and patients in the room also need some comfort."

Working in rural health centers in Bangladesh

In the first phase of the "solar cooling" project, its participants analyse different systems of solar heating and cooling. In the second phase, they will analyse the implementation of the solar thermal applications in rural health centers in Bangladesh from August on and create a feasibility study and a market survey.

Whichever solar system they favour in the end, the bi-national project has already produced other, very personal side-effects, says Wolfgang Lanser.

"At the beginning of our project I was a bit anxious, because I never before had such a close contact to people of different cultures. So I was afraid to make mistakes, to say something wrong etc., but after a while you get to know each other, you talk and behave yourself like to a friend you know since years – a very close friend. And you forget that he comes from a totally different culture. And this is really a very nice experience."

Steffen Marquardt