The PEM Fuel Cell generates electricity from hydrogen and oxygen through a chemical reaction. It is considered a zero-emission technology since the only byproducts are water and heat. Due to its high power density, low running temperatures and pressures and quick start-up time the PEM Fuel Cell is an ideal solution for on- and off-highway applications. 

Phosphoric Acid Fuel Cells (PAFC) utilize liquid phosphoric acid as an electrolyte to produce electricity from hydrogen, offering robust performance and long operational life. Although bulkier and less power-dense than PEM fuel cells, PAFCs are well-suited for larger mobile machinery and stationary power applications due to their higher tolerance to fuel impurities and reliable efficiency. 

Solid Oxide Fuel Cells (SOFC) operate at high temperatures using a ceramic electrolyte to convert a variety of fuels into electricity with high efficiency and fuel flexibility. Their suitability for electric trucks, buses, and mobile machinery lies in their potential for high electrical efficiency and the ability to utilize alternative fuels like natural gas, although their long startup times and thermal management needs pose practical challenges for on-the-go applications.