What is the lowest production rate? How much hydrogen is produced on the lowest production rate and how is the efficiency changing at partial load? How does the polarization curve look like for the stack?

The lowest production rate of the EL 4.1 is 60% of the 500 NL/h, meaning 300 NL/h. The lowest production limit was set to 60% to ensure the devices’ safety. The amount of hydrogen in the vent line is then still well below the flammable limits. The energy consumption decreases roughly linearly with the production rate setpoint. The power consumption at a given production rate can be seen in the graph below. Also, the water consumption depends on the hydrogen production.

With the electrolyser control system algorithm, ramping up the production rate by 10% takes about 21sec. Ramping down by 10% takes less than 1sec.