Energy system of Alella Green Tech center. General architecture
At Alella Green Tech we are trying to create an almost completely autonomous energy network that combines the energy produced from renewable sources to accumulate energy, necessary to increase the flexibility of the network. And here’s how we implement it:
Most of the energy for this network can be generated by photovoltaic panels that can take advantage of the solar radiation of the area of Alella. For the solar system we estimated a peak power around 50 kWp, which should be able to fulfill the energy demand of possible future upgrades in the farm, such as charging station for electric cars and many more.
The photovoltaic panels can also be flanked by small wind turbines.
So far we estimated a power of 6 kW for the wind energy production.
HYDRO POWER (LAKES)
An energy storage system, already partially implemented, will consist of a water system that will exploit the potential energy contained in a reservoir. The lake can be filled using the energy produced in surplus from renewable sources and can be used to produce electricity, using a turbine, when the internal energy grid will require it.
Speaking now about the hydroelectric energy storage system, it is possible to say that it consists of four different lakes/reservoirs: two already existing and two that are likely to be built in the future.
Water flowing from pond 1, which is the higher lake (see the figure below), to the others will produce electricity.
It is important though, to get an idea of how much electricity can be produced not only based on the energy demand but also on the amount of working hours for each lake. In fact, every lake can contain a maximum amount of water which, every time it is reached, will determine the inability of the system to produce more electricity until the lake is empty again.
The aim of the calculations was therefore to estimate the quantity of energy that can be produced through each different path (from lake 1 to 2, from lake 1 to 3, from lake 1 to 4) and the running time of each system, keeping in mind that the system should generate electricity all night long, in other words when there is no sun.
Different variables have to be taken into account such as the pipe ́s diameter, the different head through the lakes, coefficient of friction of the pipes and many more. It was calculated that it is possible to keep the water running between the lakes for around 10 hours using a tube diameter of 75 mm: this configuration will allow us to gain an instant power almost equal to half a kilowatt and a total energy of 5 kWh throughout all night. This amount of electricity* produced can fulfill the energy demand of the gate, the entrance road, the field and the laboratory.
* It’s important to note that the results just shown only take into account the electricity that can be produced between pond 1 and pond 2 because they are the only existing lakes so far. This means that there is the possibility to produce more.
HYDRO POWER (WELL)
Another possible accumulation can be realized using an abandoned well; in this well can be realized a system that allows to accumulate and to release potential energy thanks to a mass that is raised or lowered according to the necessities.
At Alella Green Tech, the energy grid project is fascinating and ambitious; in particular, the sizing of production and storage facilities and the implementation of the network control system are extremely important challenges, not only in the local context but also in the context of the energy transition that is being sought at a global level.