CooltH Engines for Rapid Refuelling of hYdrogen road freight vehicles (Project CHERRY)

Hydrogen is a key, zero-emission fuel which can be used to replace fossil fuels in many applications, including road transport. Whilst Fuel Cell Electric Vehicles (FCEVs) are available in all sizes of vehicles, the large scale of Road Freight makes hydrogen, as a light-weight and rapidly rechargeable fuel, an ideal alternative to fossil fuel based vehicles.

Whilst hydrogen is very dense in energy per unit mass, it must be compressed to high pressures (typically 350 or 700 atmospheres) for storage in on-board pressure vessels to reduce its volume sufficiently for practical use in vehicles. One challenge this creates is that rapid compression of hydrogen into vehicle tanks causes a rise in the temperature of the gas at the same time as the pressure increase.

This temperature increase leads to two problems. The first is that the density of gases is lower at higher temperature. Therefore, for the same vehicle tank pressure, less hydrogen can be stored in the vehicle tank than at ambient temperature, hence reducing the potential range of the vehicle.

The second problem is that vehicle tanks are normally made from light-weight materials such as carbon-fibre, and the materials in these light-weight tanks cannot withstand elevated temperatures (typically maximum temperatures are limited to 85°C).

The conventional solutions to this problem are either to fill vehicle tanks very slowly, allowing the compression heat to dissipate through the tank walls; or to use a mechanical refrigeration system to cool the hydrogen in the refueller storage to below ambient temperatures. The first option is highly undesirable as it negates some of the advantages of using hydrogen (being able to rapidly refuel).

The second is expensive and lowers station reliability because, due to their moving parts, chillers can break-down.

NanoSUN specialises in low cost, ultra reliable hydrogen refuellers and has already successfully eliminated compressors from its refuellers. Compressors are expensive and unreliable, so elimination has enabled dramatic reduction in the cost of refuelling stations. NanoSUN has now devised a low cost and reliable method of cooling hydrogen between the refueller hydrogen storage and the vehicle tank.

This project aims to rapidly validate this technology, to enable accelerated commercialisation in hydrogen refuelling infrastructure. The technology could be deployed both on NanoSUN's mobile cascade refuelling stations and also conventional, fixed hydrogen refuelling infrastructure. A low cost cooling technology for fixed hydrogen infrastructure has potential for disruptive impact and significant acceleration in roll out.