Essentially, the idea is to have a mini turbine inside a water pipe that would generate electricity through hydropower. Attached are specialized lightbulbs with internal batteries that charge up with the generated electricity. They can then be unscrewed from the pipes, flipped over onto a built-in stand and used to light up a room.
The concept is intriguing, and we like the creativity -- even if it is entirely impractical. See, according to Yanko Design, "The intended area of use is a country like Africa where there is severe power shortage."
The problem with that (besides the fact that Africa is a continent and not a country...) is that places without electricity to run lights most likely don't have pipes with running water. These would probably be areas where people have a communal well where water is pumped, or, more likely, women and girls have to travel long distances to collect water. Even if an area does have water infrastructure, the pipes need water flowing through at a steady enough rate to fully charge a battery, which further decreases the practicality of the design. So the locations where this can be applied are severely limited, unless it is considered more of a novelty product for off-grid lighting in developed areas than a needed tool in developing areas.
Further, how fixable is this device? If it is to be placed in developing areas then it needs to be easy to repair. Something like this probably isn't so simple to fix if it breaks... and if a bulb breaks then the whole thing is rendered pointless. Considering factors like repairability and cheap, replaceable parts are a key part of designing for developing areas.
Even with these problems, we like the thinking behind the concept -- creating light by adding a small component to existing infrastructure is compelling. Maybe this will spark ideas for a more practical design.