Abstract:

In this paper, the cost of hydrogen production by renewable energy electrolysis was systematically analyzed, and the levelized cost of hydrogen (LCOH) from alkaline and PEM electrolyzers were compared. The effects of scale, hydrogen pressure, compression and liquefaction, and input power fluctuation on the cost of hydrogen production by alkaline and PEM electrolysis were investigated. The results showed that the cost of hydrogen production was reduced with the increase of scale. When the scale of our investigated electrolysis system was increased from 1 MW to 40 MW, its fixed cost was reduced by more than 40%, but its LCOH cost was reduced byless than 25% because electricity is the main cost. The LCOH cost of hydrogen production by high-pressure electrolysis can be significantly reduced without increasing the fixed cost. With the increase of electrolysis pressure from 1 atm to 30 atm, the cost of hydrogen further compression to 700 atm will be reduced from 1 $/kg to 0.3 $/kg. The liquefaction cost was significantly affected by the scale, and the levelized cost of hydrogen production by electrolysis and liquefaction decreased from 8.7 $/kg to 5.3 $/kg with the increasing of scale from 1 MW to 40 MW. For PEM has good adaptability of renewable energy fluctuation, the LCOH cost of PEM could be lower than that of alkaline electrolysis with an increase of low power (<20% rated power) fluctuation. With the improvement of alkaline electrolysis and PEM electrolysis technology, which is better or worse should be discussed according to the specific situation.

Key words: electrolysis, hydrogen production, levelized cost of hydrogen (LCOH), compression, liquefaction, fluctuation