Laboratory Energy Hub
Our laboratory is part of the Montilivi Campus of the University of Girona, located in Girona. The lab surface is of 72m2 and is part of the research facility with total surface of 4,071m2.
The energy system that feeds the lab, in terms of both electricity and thermal energy has been designed as an energy hub for experimentation on energy efficiency management. The overall system is being managed with storage capabilities (batteries and thermal tank) to improve flexibility in the management and increase energy efficiency.
Environment monitoring
There are 16 workstations in the lab and the energy used by each workstation is monitored individually with a wireless sensor network. Moreover, the lab is equipped with the following sensors to measure the air quality and environmental conditions:
- 3 interior temperature sensors
- 1 exterior temperature sensor
- Athmosferic pressure
- Humidity
- Noise sensor
- CO2
- 2 Light sensors
- Vibration sensor
- 2 motion sensors
- occupancy detection
- door and windows open/closed sensors
These sensors are combined with the app allowing users for expressing their comfort sensation at the workplace. The information provided is being collected with the objective to adjust the conditions and improve the users’ comfort on the one hand and find out the relation between the comfort and energy consumption, on the other.
Moreover, the energy hub can also benefit from a weather station located in the Campus with the following parameters:
- Temperature
- Humidity
- Solar irradiance
- Atmospheric pressure
- Precipitation
- Wind speed
- Wind direction
Components of the energy hub
Electricity supply
Power from the grid is complemented with a photovoltaic installation: A total of 14 solar panels (3.8 kWp) connected to a 4 kWh battery. Thus, PV panels supply electricity to the lab allowing also to charge the battery. The photovoltaic solar plant connected to the Low Voltage Network has the following characteristics:
- 14 modules (Canadian Solar CS6K-280P)
- Dimensions of the module: 1650 x 992 x 40 mm
- Rated power of the module: 280 W
- Efficiency: 17.11%
- Estimated energy produced: 5,970 kWh/year
- Installed power: 3,92 kWp
And the battery installed:
- Sonnen Batterie eco 8.0
- Usable battery capacity: 4.0 kWh
- Nominal power (charging/discharging): 2,500 W
Thermal supply
Space heating and cooling is guaranteed by a ground sourced water-to-water heat-pump that incorporates an inertial water tank to store thermal energy that is used for space heating and cooling by means of the fancoil.
The geothermal system has the following features:
- Geothermal well depth: 100m
- Heat pump model: Clausius Classic
- Heat pump electric consumption power: 0,8-3.3 kW
- Heat pump thermal supply power: 3-15 kW 0-35ºC
- COP (nominal): 4.61
- Inertia water tank: 100 lts
- water-air heat-exchange: Fancoil
The water tank can be used to provide flexibility to the energy lab. When generation of PV panels is available, the heat pump can produce the thermal energy needed and store it within the water tank.
The heat pump consumption is monitored by a power sensor that sends data to our database every 5 minutes. In that way, it can be observed the cycles of consumption according to the temperature losses of the water tank, the configurated tank temperature setpoint and the office temperature setpoint. In the example of 10th March shown below, it’s visible that during midday the heat pump did not consume, coinciding with the hours with higher temperature.
Moreover, we made a shield to communicate via Modbus with the heat pump’s controller board. This shield consists of a microcontroller that reads the information stored in the heat pump’s memory and sends the environmental variables to our database. These variables are:
- The temperature of water from heat pump to water tank (and opposite direction)
- The temperature of water from heat pump to well (and opposite direction)
- The temperature of water tank (temperature prove in the middle-heigh of the tank)
- The outside air temperature
- Configuration mode: Buffer (1), Buffer+Cooling (2), 1 Zone (3), 1 Zone – 2 Systems (4), 1 Zone – Multiemitter (5), 2 Zones (6), 2 Zones – 2 Systems (7)
- Operation mode: Wintern (0), Summer (1) or Automatic (2)
- Alarm: yes (0), no (1)
- Working state: ON (0), OFF (1).
Additionally to this heat pump’s Modbus shield, other temperature sensors are also sending to the database the following variables:
- The laboratory’s air temperature
- The temperature of a 50m depth temperature probe in the well
Finally, we developed a web app to visualize these variables from all the different sensors in a single tool. You can visit the app by clicking the link below:
https://app.exit.udg.edu/geotermia/
Further steps consider improving the Modbus shield in order to both read and write to memory registers, adding the possibility to control the heat pump’s electrical consumption to maximize the use of our own PV production.
Goals of the energy hub
On one hand, this installation will allow the eXiT lab to reduce its dependency of the power grid and the use of fossil fuels from the building’s heating system. On the other hand, eXiT research group will take profit of this installation developing and testing software tools for an optimal scheduling of the generation and storage resources, minimizing the dependence of the lab on the grid or minimizing the costs taking into account energy tariffs.
The main capacities of the infrastructure are:
- Charge and discharge testing
- Environmental and air quality evaluation
- Users comfort monitoring and evaluation based on objective sensor data and users’ subjective data
- Energy usage monitoring
- Evaluation of relations between energy usage and environmental conditions
- Evaluation of relations between energy usage and users’ comfort
- Forecasting of PV generation and energy demand
- Modelling thermal demand according inside/outside temperature
- Modelling heat-pump thermal production and efficiency according to water tank and office temperature setpoints
- Optimal scheduling of storage assets
- Energy Hub modelling and optimisation
- Optimal control of HVAC assets
- Non-intrusive load monitoring studies
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