Florianus josopandojo has done a lot for the future. "I would like to work as a biogas engineer later on, and most preferably in the international arena especially in Germany and Indonesia," says the young aspiring engineer. But also Asia, America or Africa would be right for the Indonesian. Josopandojo came to Germany in year 2012 straight with just 20 years old to study the course of renewable energies. After a three-month language course in Heidelberg and a year of study preparation program in Nordhausen (Thuringia), he joined the Rottenburg University of Forestry, which offers the course of studies on renewable energies.

Flora, Fauna and Fishermen are suffering

As a part of his Bachelor's thesis, Josopandojo turned as of August 2016 to a problem known in Indonesia: a water plant called Water Hyacinth, which is located mainly in tropical countries in freshwater lakes. This fast-growing plant can cover the entire surface of a lake in the shortest possible time. This shields the flora and fauna in the lake from sunlight and prevents the formation of oxygen below the water level. This causes the fish to die and the local fishermen to suffer financial losses.

With his project, Josopandojo wanted to “kill two birds with one stone”: to free the lakes from water hyacinths and generate green energy. Although, the idea of transforming the annoying plants into biogas was not new - the Indonesian organization "Rumah Energi" had already built biogas plants at Rawa Pening Lake on the island of Java. But before Josopandojo's work they had no ideas about the energy potential of the water hyacinths. It was missing simply a measuring device for it, said the 25-years-old student.

Josopandojo worked as a project manager with his Professor Jens Poetsch (project supervisor) and with his fellow student Johannes Unger under the project name "realization of the water- hyacinth-micro-biogas-plant in Central Java, Indonesia" to promote research. Unger heads the regional group of "Technology without Borders" in Rottenburg; the organization supported Josopandojo's project, among other things, with financial resources. The Indonesian co-operation partner "Rumah Energi" set up the workers who built the micro-biogas-facilities in Indonesia.

Cooking with gas from aquatic plants

During the laboratory phase from November 2016 to March 2017, Josopandojo investigated the biogas potential of the water hyacinths as well as optimization possibilities for the micro-biogas-plants. One of his results: 11.3 liters of biogas can be obtained from a kilogram of freshly ground water hyacinths. Another result: To make one liter of water to boil, 387 liters of biogas are necessary, which corresponds to 30 kilo of fresh plant.

In April and May 2017 two micro-biogas-plants with a capacity of eight and ten cubic meters were built, which corresponds to 8000 and 10,000 liters respectively. "So far", said Josopandojo, three families have profited from it. They are now cooking with biogas, cost-free and emission-free. "Further gas pipelines could be installed, so that two more families could soon be connected to biogas.

In the future the plants could also be used for electricity generation, said the young Indonesian. But at the moment it is mainly about being able to operate gas stove environmentally friendly and low cost.

Florianus josopandojo wants to expand his project even after his bachelor and build further plants. In addition, he would like to continue his studies and his master's degree in Germany. Together with the organization "Rumah Energi", which has already been in contact with the Indonesian energy ministry, he wanted to inform the Indonesian government about this new energy generation method and at the same time to win over future projects. In the future, he hopes to receive a solid financing.

First chopping, and then fermentation - the rest can be used as a fertilizer

First, the water hyacinths are chopped in two to three centimeter size pieces. Afterwards, they are fermented for 40 to 50 days at 28 degrees Celsius with cow dung in a digester. This creates biogas. The substrate remaining after this process can be used as a fertilizer.

The cost of biogas plants depends on the size. An eight-cubic meter plant costs around 900 euros; a ten-cubic meter plant costs about 1,100 euros.

For those, who couldn’t afford this in one time, the investment can be paid out in installments. In addition, the Indonesian Ministry of Energy is sometime paying a state subsidy. Whoever sells the fermentation residue as a fertilizer can thus cover its costs in the long term.

**Artikel dipublikasikan dalam Bahasa Jerman