Konvekta, a German manufacturer of CO2 (R744) heat pump systems for commercial vehicles, has developed a new software module – “Additional Energy Storage (AES) Mode” – that eliminates the need for an electric heater in electric buses, reducing both costs and energy consumption.

By drawing a large part of the heat needed to warm the bus from the air rather than from the bus’s battery, the heat pump operates more than 50% more efficiently than an electric heater, according to a recent statement from the manufacturer.

“Currently, every heat pump vehicle also has an additional electric heater to cover special temperature peaks during winter seasons and for the pre-heating process before starting [the bus] in the morning,” said Konvekta. “With the new AES-Mode module, the CO2 heat pump system 1.7 is able to distribute 100% of the generated energy according to demand.”

“With the new AES-Mode module, the CO2 heat pump system 1.7 is able to distribute 100% of the generated energy according to demand.”


Heating efficiency in electric buses

According to Konvekta, an electric heater in an e-bus typically operates with a COP of 0.9 during its pre-heating phase, meaning that 1.23kWh of electricity is required to generate 1kWh of heat. However, Konvekta’s AES-Mode software boosts the system’s COP to more than 1.6, producing 1kWh of heat with just 0.63kWh of electricity, saving the bus operator 0.6kWh of energy for each 1kWh of heat it needs.

These results were gathered from a field study of the software, which was tested in the electric buses of Offenbach, Germany, by the city’s public transport provider, Offenbacher Verkehrs-Betriebe (OVB).

Getting the heating and cooling of electric buses right is important not only for the thermal comfort of its passengers, but also for energy consumption, cost and range.

“In various field measurements, many transport companies and bus manufacturers have found that conventional additional heaters put such an impact on the already limited energy supply that the range partially dropped by more than 50%,” said Konvekta.

Konvekta believes that electric mobility is the solution for many cities on their sustainability journey but that it requires new concepts and ideas. According to the manufacturer, its CO2 heat pumps and AES-Mode software offer additional steps towards using energy more efficiently, economically and sustainably.

As of January 2022, Konvekta had installed its CO2 heat pumps in more than 1,300 electric buses and rail vehicles. By the end of this year, the company hopes to have at least 1,800 units in the field.

Want to find out more, or have something to say about this story? Join the ATMO Connect network to meet and engage with like-minded stakeholders in the clean cooling and natural refrigerant arena.