La Poste reduces the carbon footprint of its electric vehicles

Background

For more than 15 years, the La Poste group has been pursuing an ambitious policy of reducing its environmental footprint. As current transport technologies make zero emissions unachievable, La Poste compensates 100% of its unavoidable emissions by supporting high quality environmental and community projects in France and worldwide. As a result, La Poste became the first fully carbon-neutral postal operator in 2012, and is committed to reducing its CO2 emissions in line with the Paris Agreement by 2025. In addition to the measures taken to offset its carbon emissions, La Poste is developing projects in-house based on proposals submitted by its employees. The BSCC's carbon fund, launched in 2017 by its Social and Environmental Responsibility Directorate, was set up to fund initiatives that reduce CO₂ emissions.

As part of the 2017 Carbon Fund Challenge, the GEPY (Gestion Electricité Postale Yvelines) project was selected and provided with funding for its innovative and experimental approach. A call for projects was launched as part of the process and 17 competitors responded, including Engie and Eaton, who were ultimately selected.

The aim of the GEPY demonstrator was to test a PV shade structure in the car park of the mail services platform site at Magny-les-Hameaux in Yvelines. The infrastructure provides cover for vehicles during rainy or hot weather and generates electricity to supply electric vehicles as a priority, but also the building, depending on the time of day and the demand for electricity. The goal was to supply power to the site's two electric vehicles by generating PV electricity on site, in order to minimize the impact of vehicle charging on the public electricity grid and thus make a useful connection between generating PV energy and having electric vehicles on site.

However, there was a difficulty in that PV panels only produce electricity during the day, while there is sunlight. During the day, vehicles are on the move and therefore cannot be charged, or can only be charged partially. We needed to find a way to store the electricity produced by the PV panels during the day to supply it at night when the vehicles were parked up.

Should additional electricity be required, mainly as a result of power only being generated intermittently by the PV panels, the site would be powered by the public electricity grid. For the installation to operate properly, a system based on an intelligent algorithm was required to manage the flow and control the system without the need for human intervention.

The installation occupies an area of two parking spaces, i.e. 25 m². It is composed of a PV generator made up of 15 panels located on the roof of the shade structures, with a production of 4.5 kWc, if delivered under optimum conditions. The energy storage unit, installed in the bicycle room, consists of a hybrid inverter and a second-life battery pack with a nominal capacity of 4.2 kWh.

The unit is controlled by software built into the Eaton xStorage Home system, which automatically manages the distribution of energy flows between PV production, power demand from the vehicles and the building, and the storage or recovery of the surplus. The electricity produced by the solar panels is either stored in the battery as direct current, or transformed by the hybrid inverter into an alternating current to meet the demands of the electric vehicles or the building.

In winter, the system can also make some trade-offs, recharging the battery on the public electricity grid during off-peak hours and recovering stored electricity during peak times, to minimize the impact on the public grid and reduce energy bills. The software, built into the xStorage Home system via an embedded user interface, automatically manages power flows, optimizes system operation and delivers reports. It is hosted on a secure Cloud and can be connected to the La Poste intranet in future in order to better monitor how the installation is operating. The software allows flow to be displayed in real-time on a tablet or smartphone, with the ability to access data on electricity production or self-consumption over a day, and over the previous month. The installation monitoring data also includes a calculation of consumption.

In operation since February 2019, the GEPY project has provided an average of almost 60% of the power supply to the two electric vehicles on site. The electricity demands of the two electric vehicles were covered at a minimum of 50% between February and October, 75% from April, and 80% from June until September.

With an average of 59% of the two electric vehicles' demand covered over the observation year, this represents 4844.1 km traveled by PV electricity over a total of 8760.3 km and a saving of 1.52 tons of CO2 compared to a diesel vehicle. To this should be added the carbon footprint of electricity produced locally versus electricity produced by the grid, which amounts to nearly 30 kg. The 4493.5-kWh PV production of the shade structures was 100% self-consumed on site, 40% being used for vehicles and 60% being used for the building. The electricity fed back to the building partly powers e-bikes and e-scooters at the Magny-Les-Hameaux site. The benefits are paying off for employees too.

In summer, the shade structures that house the vehicles prevent the cars and batteries from overheating. The postal workers are truly proud to drive vehicles powered by solar energy and have found that the impression among the public is positive, highlighting La Poste's exemplary role in fostering solutions for energy transition and responsible transport.