Electrochemical technologies have a great potential for increasing efficiency of synthesis of sustainable fuels and their utilization for power generation for different applications. Switching from gaseous fuels (H2, CH4) as an energy vector to liquid fuels has numerous advantages including higher energy density, available infrastructure and increased safety. Low footprint and cost of storage and transportation of carbon-neutral liquid fuels (CNLFs) enables vehicle electrification (directly or as hydrogen carrier), long-time energy storage and effective long-distance energy transportation. Easily liquefied ammonia (4.25 kWh/L) is one of the most promising CNLFs. It can be used directly in fuel cells or as hydrogen carrier for PEM fuel cells thus enabling the infrastructure of hydrogen fueling stations for public transportation. The Renewable Electricity to Fuels through Utilization of Energy-dense Liquids (REFUEL) program funds the development of transformational technologies to reduce the barriers to widespread adoption of intermittent renewable energy sources by enabling the conversion of energy from these sources, water and air to energy-dense CNLFs, mostly ammonia, (Category 1) and their conversion back to electricity using fuel cells (Category 2). The program objective is to demonstrate delivery of source-to-use electricity (including production, transportation, storage, and conversion) at the cost below $0.30/kWh to be competitive with other carbon-free delivery methods.
Development of novel synthetic methods for CNLFs and regenerative fuel cells for energy storage is also being funded via OPEN program. Possible future ARPA-E program targeting the use of CNLFs for transportation (in hybrids, range extenders, APUs) will be also discussed.