“Sofiyska Voda” is the company which administers water and sanitation for the Bulgarian capital – Sofia. Now, the company has announced that it wants to join in on a project for producing renewable energy from its existent infrastructure. Placing electricity generators inside the pipes which deliver water to the homes of Sofia’s 1.7 million inhabitants is an innovation with broad consequences.
The idea of producing electricity from the pipes that deliver water to our homes is not a new one. In Sofia, it was first pioneered in 1998, when the project was not accepted by the capital city’s municipality because of the costs. Yet, in 2003, the plan was re-born, and the search for investors was initiated through public procurement contracts. Since then, numerous ecological and land-ownership investigations have been completed, and plans to construct six such installations are now well underway. It only seems logical that the company administering the water pipelines be included.
The technology behind the idea is rather simple. Small hydro-power stations are placed in strategic places where pressure in the pipes is reduced artificially because it is too high (e.g. due to gravity). These stations would not only regulate the pressure, but also produce renewable energy. It sounds like a win-for-all situation, and even the biggest skeptics have noted that only in very extreme situations the negative side would be to stop the delivery of water to the most distant suburbs. Taking the big picture into account, it is a risk worth taking.
Nevertheless, the citizens of Bulgaria’s capital should not expect hydro-power stations sprouting in the middle of their city. These installations will be constructed in the suburban areas, especially in the foot of the mountain above the city – Vitosha.
In a city where electricity consumption peaks at 2,000 MW per hour, the question of how much could these hydro installations contribute to the share of renewable energy in the city comes up. In total, the six electricity-generating stations are expected to contribute 6 MW per hour. Some would say that this is a small share, but the significance of the project is still quite large.
The final cost of all these plants is projected to be 15 million Euro (initially, it was 9 million Euro, but due to delays, it has increased). It seems a small price to pay for diversifying the capital’s energy mix through renewable energy stations that can be constructed in a short amount of time.
The link of these hydro-power stations to the grid of the city depends on the local energy distribution company – CEZ Electro. So far, the company has commented that there have been no negotiations with them about including these installations into the grid, but this is expected to happen soon since construction will be commenced as soon as the public procurement procedure in completed. Furthermore, Sofia’s municipality has estimated that 1.5 million Euro per annum is a realistic estimate of CEZ Electro’s profit from these installations. This is certainly an incentive which will draw in investors.
Such small-scale renewable energy projects, using innovative technology and natural resources are the type of ideas needed in a city with high electricity consumption. Yet, it is only possible due to the unique circumstances, such as Sofia’s location. Whether this idea can be used by other cities depends on a range of conditions and requires thorough investigation.