Prototype of PRs turbine presented at the H2O 2016 exhibition in Bologna (Italy). The electronic parts, along with the pressure sensors and the control panel, are missing.
Island (Region, Province, Country): Sicily, Italy
Population: About 5,000,000 inhabitants
Budget / cost of the project: About 10,000 K€
Project objectives: Large-scale application of PRs devise in agriculture for simultaneous energy generation and discharge control; dissemination of energy saving culture among farmers.
Project description of activities and specific interventions:
A new device, named Pressure Recovery system (PRs), has been recently developed by Hydropower net company network (Fig.1). PRs is based on a Banki type microturbine with pressurized outflow, which can be installed along pipes like any other pressure and/or discharge controlling valve. PRs provides two services: a reduction of the pressure and a corresponding production of electric energy. It is suitable for a large range of powers (from 10 to 1000 KW) and has an hydraulic efficiency larger than 75%.
PRs could provide important benefits specially for reclamation consortium organizations (RCOs) and for their farmers. RCOs are the water managers delivering water to the single farmers and, for farmers in arid areas, the cost of water in their sheet balance is among the major ones. The pipe transportation and distribution networks managed by RCOs are usually very old and they often include several open water tanks, as well as pressure reducing valves (PRVs) followed by pumping systems, with a huge useless consumption of energy.
The project includes, along with a partial pipe renovation, the substitution of the PRVs and of the open water tanks, not serving for storage, with the new PRs. In the island of Sicily about 11 RCOs have been serving the farmers up to the end of this year, but their number should drop to 1-2 along the next one. A first monitoring and design activity should provide the executive project of the possible specific actions, followed by the license request for hydroelectric power production. This license, in Italy, usually requires long times, but special short-cuts are available for RCOs. Finally, PRs installation and connection to the electric grid could follow. For maximum power smaller than 100 KW connection with the low voltage grid is possible. For higher powers, connection with the medium voltage grid is required.
The Capital Return Time, for any PRs providing a medium power larger than 25-30 KW is smaller than 2 years, if significant civil works are not required for their installation. Gross powers of the order of several MWs are dissipated at present in each single consortium and they could be reconverted in electrical energy by means of the proposed system.
Public outreach, education and awareness efforts and results:
Diffusion of energy saving culture is fundamental for the future of agriculture in Sicily and in all the islands where acquisition of water can be associated to significant energy costs. Important examples are given by groundwater, which often requires drilling deep wells associated to significant pumping costs, or desalinization. On the other hand, medium and large size islands with significant rivers are often equipped with large public hydraulic infrastructures, like dams, weirs, springs or large wells that allow a strong reduction of water catchment costs.
Most of these infrastructures catch the water at high topographic levels and the water is delivered to farmers through gravity. Farmers are usually not aware of the energy value of water, which is usually not fully exploited before its agricultural or domestic consumption at much lower topographic (and energy) level. Renovation of water distribution network and inclusion of PRs instead of traditional PRV would provide also additional environmental benefits like: a) reduction of water losses along pipes and their junctions, b) demolition of existing open water tanks not required for storage, which have a significant maintenance costs and can also have a bad impact on the landscape skyline.
PRs can also be used by the single farmer to get the energy required for long distance valve operation and monitoring, where the electric grid is too far and its connection would require a large investment cost. For this reason, dissemination activity could be an important part of the project.
Economic value added and how calculated:The economic benefit of the installation of a single PRs connected to the electric grid, in Italy, can be calculated starting from the subsidized value of hydroelectric energy, which is, in 2017, 0.21 €/KWh per 20 years. A pipe carrying an average flow rate of 0.5 mc/s, where a dissipation of 3 bars is available, can produce a gross power equal to 150 KW, corresponding to a net power of about 100 KW. The corresponding income is, in one year, equal to 184,00 euros. The cost of microturbine, with electric generator and control panel, is just a fraction of this yearly income (100-150 K€), and becomes a bit more including also all the components and the work required for the electric connection to the grid. All the other costs, if existing, are related to the civil works needed to install the turbine. These costs are missing if the PRS replaces a previous PRV, also because the last-generation of PRVs are usually all equipped with electronic controls, if the grid connection is available.
Many hydraulic infrastructures, among them also treatment plants, have a large energy consumption, that can be balanced by the hydropower production of a new PRs. In this case the benefit of the new device for the water manager is independent from the public financial support and has not temporal limit.
Benefit evaluation in the case of PRs disconnected from the grid is more difficult and case-dependent. In this case the sought after energy is usually required by long-distance monitoring and control of water distribution network and its amount per day is quite small, along with the cost of the turbine. The benefit given by the long-distance control is mainly in terms of reduction of maintenance and operating costs, as well as in the improved control of the overall distribution network.
The energy expenses of a single CRO per year is, in Sicily, about 500 K€. Assuming a total cost of 5,000 K€ for the 10 CRO, a total investment of even 10,000K€ also including small civil works and dissemination activities would be financially justified.
Ecological and social project outcomes:
The most important ecological benefits provided by the PRs installation are, along with the reduction of produced CO2, the reduction of water costs for farmers mainly in high altitude agricultural areas, where the water has to be pumped by the RCO with high energy costs. In these last years, in Sicily, the increment of the energy costs has forced many farmers to either abandon the land or to drill very deep well, leading to still high energy costs for pumping. The loss of cultivated land, as well as the aquifer perforation have both long term negative effects on the environment.
PRs is produced by Hydropower net, a network of companies that has transformed the research ideas of a young Spin-Off company, located in Sicily and named Wecons, in industrial production. Wecons exports the research experience capitalized in the hydraulic Department of the University of Palermo (Figs. 2 and 3); it is part of Hydropower net and the success of this project could help the integration of the strong industrial production well established in many European regions with the emerging ideas coming also from the less developed regions located in the south of the world.
Experimental device for the efficiency testing in the Palermo University lab. The turbine is put in a pipe loop about 18 meters long, where discharge and pressure before and after the turbine are measured and recorded. Output mechanical power is measured through a torque meter set between the turbine axis and the electric generator.
Banki turbine with free outflow designed by Wecons installed at the S.Anna disconnection tank of Caltaqua water manager company (Caltanissetta, Italy).