The transportation industry is taking big steps towards zero-emission vehicles, seeking to reduce the environmental impact of heavy trucks. Europe-wide data highlights the crucial role that the heavy transport sector plays in terms of Greenhouse Gas (GHG) emissions, being responsible for more than 6% of total GHG emissions and 28% of road transport emissions.
The good news is that innovative solutions are emerging in response to the need for more sustainable mobility. Battery Electric Vehicles (BEVs) and Fuel Cell Electric Vehicles (FCEVs), together with hydrogen-combustion trucks, are just some of the focal points in achieving the objective of zero emissions.
With the adoption of cutting-edge technologies and the implementation of clean energy sources such as photovoltaics, heavy transport can transform from a major contributor of GHGs to a pillar of sustainability.
Zero-emissions vehicles: where do we stand on heavy vehicles?
Trucks and buses will need to be fully decarbonized to achieve climate neutrality by 2050. The European Commission’s proposal to revise CO2 emission standards for new Heavy-Duty Vehicles (HDVs) is the most significant legislative initiative for regulating climate emissions from trucks and buses in Europe, with the aims of lowering CO2 emissions by 45% for HDVs in 2030, 65% in 2035 and 90% in 2040. While the EU as a bloc is beginning to navigate the direction the regulation should take, 10 EU countries have already committed to shifting to 100% zero-emission HDV sales by 2040 (namely AT, BE, HR, DK, FI, IE, LT, LU, NL, and PT). They did so under a global Memorandum of Understanding, which was also signed by the United Kingdom, Norway, Switzerland, and Turkey, together with Canada and the United States. California, whose emission standards are commonly followed by other U.S. states, has recently proposed legislation that includes an objective of 100% zero-emission trucks and buses being sold as early as 2036 (1).
Zero-Emission Vehicles (ZEVs) include Battery Electric Vehicles (BEVs), Fuel Cell Electric Vehicles (FCEVs) and hydrogen-combustion trucks. These are among the available technologies that can rapidly reduce emissions from new sales, fully decarbonize the heavy vehicle sector in the long run and eradicate harmful air pollution.
These are complemented by additional solutions to expand the range by producing energy directly on board. We are talking about the electric axle and photovoltaics, for example, which can be used to charge a battery pack that can power auxiliary and other important services such as refrigeration units on chilled trailers. Indeed, the latter are major contributors to pollution, relying on refrigeration systems whose units predominantly run on dated and highly polluting diesel engines. This is demonstrated by certain data provided by the California Air Resources Board in its 2022 Technology Assessment: Non-truck Transport Refrigeration Units (TRUs). For the approximately 33,000 refrigeration units installed on trailers circulating in the state of California (2), The PM2.5 emissions produced for the year 2021 are 171 tons, NOx emissions are 4880 tons, and CO2 emissions are 757,913 tons (3). Such extraordinarily high numbers make us realize how important it is to also address this aspect of heavy transport as soon as possible, in order to truly achieve zero-emission vehicles.
Technologies applied to refrigerated trucks
Integrating solar power on refrigerated trailers is one solution making its mark on the path towards decarbonizing heavy-duty trucks. The large areas available on trailers are perfect for installing solar power systems capable of producing considerable amounts of energy, especially with technological advances in the field that have led to increasingly efficient photovoltaic cells.
In this type of application, the maximum heights imposed by law in order to respect the aerodynamics of the vehicles and so as not to impact the weight of the vehicle, the technology of reference is the flexible solar power panel, just a few millimeters thick and weighing about 2.5 kg/m2 compared to the 12-plus of traditional glass panels. This lightweight product is perfectly adaptable to a variety of surfaces and resistant to the intense vibrations of road driving.
But how does a photovoltaic system for refrigerated trucks actually work?
1 - Flexible panels capture sunlight
After a thorough analysis of the available space and the energy needs of the vehicle, flexible solar power panels are installed on the roof (but potentially also on the sides) of the trailer in order to convert sunlight into electricity. The panels produced by Solbian specifically are made with cells capable of converting over 25% of sunlight into electricity, allowing high powers to be achieved even with small spaces.
2 - Energy conversion
The energy from the panels is regulated by the MPPT (Maximum Power Point Tracking) charge controller, the actual “intelligence” of the photovoltaic system, which takes care of charging the battery properly, but also exploiting the solar power module in the best way, without losing a drop of energy.
3 - Storage and distribution
The battery stores all the energy collected then distributes it to the trailer’s refrigeration unit to ensure proper operation.
How much can be saved with photovoltaics fitted to refrigerated trucks?
A study conducted in 2017 showed six 40-ton refrigerated semi-trailers equipped with irradiation sensors collected enough data to estimate annual savings of up to 1,900 liters of diesel fuel per individual vehicle (4). This figure cannot be considered as absolute, since it depends on the routes taken, the type of vehicles and the extent of the solar power system, but it does help to better understand the impact that on-board PVs can have.
Reduced diesel fuel consumption is bolstered by extended battery life, with solar helping prevent power surges and deep discharges. In this way, batteries require less maintenance and replacement costs are spread over a longer period.
The reduced fuel consumption and maintenance costs gradually offset the initial investment, which can mean a significant financial benefit in the long run and encourage adoption of this technology within corporate fleets.
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Flexible photovoltaic panels: Examples of application
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Bibliography
- European Federation for Transport and Environment (April 2023), Truck CO2: Europe’s Chance to Lead, Position Paper on the CO2 Standards for Heavy-Duty Vehicles (https://www.transportenvironment.org/wp-content/uploads/2023/04/202304_HDV_CO2_position_paper_final.pdf)
- California Environmental Protection Agency Air Resources Board (August 2015). Technology Assessment: Transport Refrigerators (https://ww2.arb.ca.gov/sites/default/files/2020-06/TRU%20Tech%20Assessment%20Report%20ada.pdf)
- California Air Resources Board (October 2022). 2022 Technology Assessment: Non-Truck Transport Refrigeration Units (TRU). Trailer TRUs, Domestic Shipping Container TRUs, Railcar TRUs, and TRU Generator Sets (https://ww2.arb.ca.gov/sites/default/files/2022-10/CARB%202022%20TRU%20Technology%20Assessment%2010-14-22.pdf)
- Fraunhofer Institute for Solar Energy Systems ISE (2017). Research at Fraunhofer ISE Investigates Integrated Photovoltaic Modules for Commercial Vehicles (https://www.ise.fraunhofer.de/en/press-media/press-releases/2017/research-at-fraunhofer-ise-investigates-integrated-photovoltaic-modules-for-commercial-vehicles.html)
