Hi guys,
I recently passed 100 views and, considering 50 views
from family and friends, it means that the other half are people who have read
my blog!!! Thanks for that!
Today I’m going to introduce more in detail my
project, but before I’d like to give you more info about the energy harvesting
applied to the roads.
Basically, the exploitable energy sources are the
solar radiation and the vibration due to the passage of the vehicles. Starting
from this simple classification, the following energy harvesting systems can be
listed (clicking on the name you will be redirected to the website of the
manufacturing companies or to some interesting paper):
- Photovoltaic roads: they
aim to convert the sunlight in electricity. A photovoltaic road consists
of three principal layers: a semi-transparent top layer able to support
the traffic load, guarantee the adequate adherence and, at the same time,
allow the passage of the sunlights to the bottom layers; an electrical
layer where the solar cells are located and finally a base layer for the
transmission of the loads to the subgrade.
Figure 1. Solar
road by Wattway
- Asphalt solar collectors:
during the summer the solar radiation increases the temperature of the
asphalt pavement up to 70°C. The idea is to exploit the temperature
gradient and to transfer the heat energy in a fluid pumped inside some
pipes, which are imbedded into the pavement.
Figure
2. Example
of asphalt solar collectors
- Air-poweredenergy harvesting pavement: the
system is based on the same concept of the asphalt solar collectors, but
the pipes are replaced with conduits where the heat-transfer fluid is the
air. The result is a continuous airflow, which can cool the pavement down
during the summer or heat it up during the winter.
- Heat pipes: it is a system able to transfer thermal energy
quickly. Each pipe is sealed at both ends and it is lined with a wicking
material. The system works for a given temperature and pressure, allowing
an equilibrium between liquid and vapor state of the fluid enclosed in the
pipe. In particular, the internal liquid (into the wicking material)
absorbs thermal energy from the pipe surface and evaporates. Pressure
forces moves the vapor to the cooler part of the pipe, where it releases
heat, condensing back into liquid. Finally, the capillary action from the
wicking structure transports the liquid back and the cycle starts again.
Heat pipes are used for example as de-icing systems.
Figure
3.
Principle of heat pipes
- Piezoelectric materials: when
a mechanical strain is applied to the piezo-electric materials, an
electrical charge occurs on the surface of the crystal. The piezo-electric
materials can be imbedded into the asphalt in order to use the energy
generated by the vehicle motion or the pedestrian passage.
Figure
4. Example
of piezo-electric road
Regarding my project RA2ROAD, it fits into
the category of systems able to exploit the solar radiation. The idea is to
realize a hybrid system able to generate electricity and store energy from the
sunlight. The prototype is composed by 4 layers: i) a semi-transparent top
layer made of glass aggregates bonded together through a polyurethane glue; ii)
an electrical layer containing the solar cells; a porous layer for the
circulation of a heat-transfer fluid; iv) a waterproof base layer.
Figure 5. RA2ROAD prototype scheme
The top surface plays a fundamental rule because it
has to guarantee friction, support traffic load, protect the solar cells and,
at the same time, allow the passage of sunlight and maximize the heat transfer
to the lower layers.
The porous layer allows to collect energy thanks to a
heat-transfer fluid, as for example the water. Water can be stored and reused
as de-icing system for the road or to heat the near buildings. Finally, the
waterproof base layer prevents the loss of the heat-transfer fluid because of
the infiltration into the grown.
If you were
brave enough to read all the post and you have some suggestions, questions or
advices, or you just want know more in detail my project, feel free to contact
me at any time.
See you soon
Domenico
“The research presented in this
report/paper/deliverable was carried out as part of the H2020-MSCA-ETN-2016.
This project has received funding from the European Union’s H2020 Programme for
research, technological development and demonstration under grant agreement
number 721493”