AuxPaC will deliver a cost-effective zero emission auxiliary system for power and cooling, by adapting the cutting-edge Dearman Engine (DE), a rankine-cycle expander powered by liquid nitrogen (LiN), to cut the well-to-wheel CO2 emissions of refrigerated trucks and air-conditioned buses by 35%, with potential for up to 85% if production of the LiN “fuel” is used to absorb wrong-time renewables; the system offers total cost of ownership savings without subsidy. The engine is at prototype stage as a truck refrigeration unit; the AuxPaC project aims to improve efficiency, so that the same cooling or air-conditioning load can be met with a surplus of electrical power for vehicle auxiliary systems, including electric tail-lifts or doors, brake and steering assistance, and lighting, all currently provided by the main engine and often requiring extended idling. The system is also applicable to electric buses and delivery vans, avoiding depleted range, and providing cooling to power electrical systems. The project brings together Dearman, Hubbard refrigeration and Birmingham University, to study improvements to engine & system efficiency, and deliver lab-based hardware validation.