Advent Technologies A/S uses High Temperature PEM systems (HT-PEM). But there are also various other types of fuel cells based on different technologies. Here’s a selection of the most significant fuel cell technologies.

Low Temperature Proton Exchange Membrane Fuel Cell (PEMFC)
Operating Temperature: Around 50-100 degrees Celsius
Electrical Efficiency: 40-60%

PEMFCs operate at a relatively low temperature, have high power density, and can vary output quickly to meet shifts in power demand. In applications where quick start-up is required, such as automobility, PEMFCs are well-suited. PEMFCs can be scaled from several watts to several kilowatts and into larger systems. They’re fuelled with hydrogen gas, methanol or reformed gas. PEMFCs can be applied for a variety of commercial applications within telecommunication, data centres and residential markets, to auxiliaries.

High Temperature PEM (HT-PEM):
Operating temperature: 100-200 degrees Celsius. Advent’s fuel cells operate at 150-180 degrees Celsius.
Electrical Efficiency: 40-60%

HT-PEM fuel cells are similar to LT-PEM fuel cells but operate at higher temperatures. HT-PEM are often integrated with fuel reformers, thus allowing a wider variety of fuel quality. HT-PEM fuel cells are ideal for commercial use, e.g. as range extenders for electric or hybrid vehicles. System cooling and heat rejection is often more convenient due to the higher operating temperatures.

Direct Methanol Fuel Cell (DMFC)
Operating temperature: 60-130 degrees Celsius
Electrical Efficiency: Up to 40 %

DMFCs are also PEM fuel cells, but instead of being fuelled by a gas, they are fuelled directly by a methanol/water mixture. There are some advantages by direct utilization of the liquid fuel, for example the possibility of using passive supply of fuel or air, avoiding balance-of-plant power losses, and also using the fuel flow stream as a cooling system. Typical drawbacks are inherently low efficiencies requiring very large cooling surfaces, hence making them mostly relevant in the low power range.

Alkaline Fuel Cell (AFC)
Operating Temperature: Around 23-70 degrees Celsius
Electrical Efficiency: 60-70 %

AFCs were some of the first fuel cells developed and were used on space missions in the 1960s to provide both drinking water and electricity. AFCs are easily poisoned by small quantities of CO2, for which reason they’re primarily employed in controlled aerospace and underwater environments.

Phosphoric Acid Fuel Cell (PAFC)
Operating Temperature: Around 150-200 degrees Celsius
Electrical Efficiency: 36-42 %

PAFCs utilize the great proton conductive abilities of phosphoric acid and can also operate using reformed hydrocarbon fuels or biogas. They’re considered the “first generation” of modern fuel cells and the first type to be used commercially. The PAFCs are usually used for stationary power generation but can also be used for large vehicles.

Molten Carbonate Fuel Cell (MCFC)
Operating Temperature: Around 650 degrees Celsius
Electrical Efficiency: 50-60 %

Due to the high temperature levels at which MCFCs operate, methane and other light hydrocarbons in these fuels are converted to hydrogen within the fuel cell itself. The primary disadvantage of MCFCs is durability. MCFCs are ideal for large stationary power and CHP applications, and are available as commercial products.

Solid Oxide Fuel Cells (SOFC)
Operating Temperature: Around 1,000 degrees Celsius
Electrical Efficiency: 50-60 %

The high temperature allows the SOFC to reform fuel internally. However, the significantly high temperature results in a slow start-up process and requires significant thermal shielding to retain heat and protect personnel, which might be acceptable for utility applications, but not for transportation. SOFCs are best suitable for large stationary applications.