Efforts to reduce the energy needed for the operation of our molecular beam epitaxy lab

Abstract The climate crisis and rising energy costs have motivated us to analyze the energy consumed by the operation of the molecular beam epitaxy (MBE) lab at our institute. This research lab houses 13 growth chambers for different material systems. Its operation requires in total 156 kW. 31% are needed for cooling water, 20% for cryo pumps, 17% for liquid nitrogen (based on the energy required for liquefaction), and 17% for ventilation. With 15% the electricity required for powering the actual MBE systems as a matter of fact amounts to the smallest category. In order to save energy, on the one hand we improved operation, i.e. we reduced the ventilation during off-hours and increased efforts to switch off liquid nitrogen and cryo pumps for those times. On the other hand, we changed hardware. In particular, we removed ventilation filters and replaced cryo pumps by turbo pumps because the latter consume only one tenth of the electricity at the low gas loads common for MBE. This analysis is partially specific to our facilities but may still provide inspiration and guidance to reduce the energy consumption in other MBE labs.