Producing drinking water from seawater with waste energy

German firm Taprogge and ESACO (Vietnam) are jointly investing in seawater desalination technology in the country. The Saigon Times Daily had a talk with Detlef Taprogge, CEO of Taprogge, about the Taprogge Terrawater Technology during a recent demonstration of a system using this tech in HCMC’s Can Gio District. Excerpts:

The Saigon Times Daily: What is the specific of this system?

- Detlef Taprogge: It’s a system based on the use of waste energy. We’ve engineered the solution that allows us to use energy levels between 80 and 100 degrees Celsius that can be found in many industrial plants. It’s waste energy. We were inspired by the nature’s water cycle. We do nothing but what nature does: In nature we need the sun to heat up the water on earth which finally condensates as clouds and precipitates as rain drops back to earth.

In principle, we heat up a stream of seawater or wastewater to a level of 80-100 degrees Celsius, and then let it drop down. Simultaneously a counter-current air stream lifts the water drops up. While rising up, the air takes up more and more humidity as its temperature increases, and we then bring the air – highly loaded with humidity - in contact with a colder surface so that the humidity in the air condensates into pure water of distillate quality.

Does this system use chemicals like other desalination systems do?

- Well, a very important point is that our system is different from any other desalination system. It does not use chemicals. Traditionally, if you separate seawater into a good stream and a concentrate stream, the chemicals you add will also end up at the concentrate, in the so-called “brine”, which may be discharged to the sea, again. We don’t want that. Our desalination process does not pollute the source water.

Can one use solar energy to run the system?

- Solar panels are ideal. The ideal full process would be to couple solar panels with our system. And that is a “green” plant because it is CO2 free. We do need, though, a tiny portion of electricity, but much, much lower than anything before. Another application may be the following: imagine, you have a generator set, a diesel engine, for instance, to produce energy - electricity. But you waste in this diesel engine may be 60% of the energy. It all goes out through the chimney or is destroyed in the cooling water circuit. This is wasted energy. For our technology, however, the temperature of the cooling water circuit is valuable.

How about combining a diesel engine that produces electricity with a Taprogge Terrawater System, then you produce electricity plus water. In this case, you increase the efficiency of the diesel engine, by helping produce drinkable water. And when you are on an island, you need electricity and water. Then life starts.

According to you, how can Vietnam benefit from this system?

- What I know is that there are lots of studies on water issues of the Mekong Delta, where people live in small communities. It is very expensive for the Government to put here a good deal of piping for water distribution. Then, how do the people get safe drinkable water? Well, that is one opportunity, for villages and small towns, to make water available from a seawater source. The second problem that is known in Vietnam is arsenic water, especially in the Hanoi area. We could take the water there and convert it to drinkable water with our system. The third application field is industry. That is probably true for many countries, particularly when you have a wastewater stream that today is emitted to the environment, to a river, for instance. Our system can help convert this wastewater to drinkable water. With this system, you can even convert wastewater of an industrial plant to an extremely high level of water quality, to distillate level. 

Where does the idea come from?

- The new desalination technology was born at the engineering school of the Bochum University, and its fathers were Dr. Thomas Brendel and Mr. Till Schlickum. But, in fact, the technology was initiated by Dr. Brendel in 2003; Mr Schlickum, an engineer, has perfected the concept further. We took over their idea, and our target was to commercialize it in the environment for human beings and for industrial applications as well.

And when did everything start?

- The idea of commercializing such a new way of producing drinkable water from seawater started in 2007. We deal here with a thermodynamic process. A lot of research activities, tests and laboratory sets were required in which the principles of this technology were tested. Once a lab was finished, we concentrated on industrializing the system that we called “Taprogge Terrawater”, to make it rough and sturdy enough for everyday use.

How much does the system cost, let’s say when you install it on an island, without any source of electricity?

- You probably have on an island a diesel generator set. The minimum of electricity that you need, you can take from the Genset. Also you take the heat generated by the diesel engine so far wasted as a heat source. That’s all in terms of energy, so there is no investment at all in any energy generators, because you get it directly from the machine free of charge.

The price of a Taprogge Terrawater System has to be project-specific. There is no fixed price for it, because it depends on what energy levels are available. The initial investment in our new system would be higher than in the traditional systems, but our running cost is essentially zero. There’s zero energy cost, zero chemical cost, and almost no operation and maintenance cost. You don’t need an engineer to run this system, just anybody with a basic training about the system.

So this system only works on a small scale?

- The basic system is a 5 cubic meters per day unit. However, you can add more units to it. If you want 100 or 500 cubic meters, you just add more units. The system is modular.

Source: english.thesaigontimes.vn

Collect by Nhu Ai SAPUWA