Combining sustainability & economic efficiency: pumps used as turbines
The construction of small hydropower stations to be used by farmers in far-flung locations or remote communities is possible, but often too expensive to be practical. A far more cost-effective solution is the use of a conventional and comparatively low-cost pump which is used as a turbine.
A team from the university of Itajubá conducted the PAT/IG project, which involved a pump used as turbine (PAT) and an electric motor as induction generator (IG) to generate electricity at the hotel premises of a Brazilian Fazenda used for ecological and nature tourism.
KSB Meganorm proves highly suitable
KSB’s Meganorm 200-250 was selected as the most suitable pump; it is designed for a nominal flow rate of 0.21 m3/s and a head of 15 m, achieving an efficiency level of 84 %.
A three-phase motor from WEG with a rated voltage of 220 V and a mains frequency of 60 Hz designed to provide a rated output of 45 kW was chosen as an induction generator.
The PAT’s speed control is performed via a butterfly valve upstream of the generator unit which is controlled by an electronic unit.
Objective: Sustainability and environmental protection
The Fazenda’s premises are located at the Boa Vista river, 60% of whose water is used to protect the rapids and fish farm ponds. The remaining 40 % of the water is harnessed for power generation.
In order to calculate the premises’ actual energy requirements, an inventory list of the Fazenda’s existing electric devices and components together with their respective power requirements was compiled. To estimate peak demand, the power requirements were also calculated for times when the Fazenda is leased for events.
Taking a planned extension into account, the maximum total demand was determined to be 38.2 kW with a theoretical peak demand of 43 kW.
Efficient: pump used as turbine
The field test results revealed that the operation of a pump used as a turbine can be extremely efficient. “We are enthusiastic about this kind of energy generation,” says Luiz Carlos B. Reis, the owner of Fazenda Boa Esperança of the overall experience. “In order to keep meeting our electricity demands in an ecological manner in the future, we are currently planning the installation of another PAT/IG set.”