Electrolyzers capital cost

For the forecourt case, electricity represents 58% of the cost of the hydrogen, and the capital costs represent only 32%. For the small forecourt case, the electricity contribution drops to 35% while the capital costs become the major cost factor at 55%. In the neighborhood case, the capital costs increase to 73%, but electricity costs are significant at 17%. This analysis demonstrates that for all systems, the electricity price is a contributor to the hydrogen price, but for small-sized electrolyzers, capital costs are more significant. 

SAU 08] Saur G., Wind-To-Hydrogen Project Electrolyzer Capital Cost Study Renewable Energy Laboratory, NREL/TP-550-44103, December 2008. 

For a given wind power installed, the sizing of the electrolyzer is not trivial. In the case of "stand-alone" systems, a one-to-one approach is often proposed, with the electrolyzer power input being equal to the nominal power output of the wind turbine. In this way, the electrolyzer should be able to retrieve all the wind power in the absence of load. In grid-connected systems, the same approach leads to the choice of an electrolyzer with a power supply equal to the power output of the wind turbine minus a "base load." However, the specific capital cost of the electrolyzer being almost equal to the cost of a wind turbine, it is important to take into account the capacity factor of the electrolyzer that will always be smaller than that of the wind turbine. 

The actual capital cost of different electrolyzers operating at pressures between atmospheric pressure and 30 bars is presented in Figure 5.10 based on offers from manufacturers. There is a wide variation in the specific capital cost of small-size electrolyzers due to the different technical characteristics and options included. The specific capital cost of very small laboratory electrolyzers may exceed 30,000 /kW, but has not been shown here for simplicity. There are no large variations in the specific cost of medium-to-large-size electrolyzers, that is, above 200 kW, mainly because there are very... 

Figure 7 shows that if SPE electrolysis meets its development goals, minimal capital investment would be required to install an electrolyzer and rely upon purchased electric power. Figures 7 and 8 both suggest that considerable advantages would be obtained if capital costs of the coal-based processes could be reduced. 

A more important conclusion is reached from Figure 10, which indicates that there would be severe penalties in operating the coal and oil plants intermittently. It also indicates that even electrolysis, which has been promoted as an off-peak power user, would be very expensive if operated below the 20% to 30% plant factor that is associated with "cheap off-peak power. The huge reduction in capital cost promised by the SPE electrolyzer offsets this somewhat, but operation of even an advanced electrolyzer at less than 20% of the time (5 hours/day) is unattractive compared with a dedicated, full-time reformer or gasifier. The low capital cost of steam reforming is again shown to advantage. 

The impact of this difference in electrolyzer cost on the system cost is shown in Figure 12. The program goal of 100/KW allowed for some difficulties in achieving all of the calculated cost bogies,and, with today s technology, it appears that the capital cost for a 58 KW system could be approximately 118/KW compared with the 100/KW goal. 

In the future, if the cost of the fuel cell system approaches 50/kW, the cost of the electrolyzer is also expected to approach a low number (about 125/kW). Such low capital costs for electrolyzer units, together with levelized electricity costs in the neighborhood of 0.02 to 0.03/kWh, would result in a competitive hydrogen cost. It is also estimated that for a photoelectrochemical method to compete, its cost needs to approach 0.04 to 0.05/kWh. The order-of-magnitude reductions in cost for both hydrogen processes are similar. 

The cost of hydrogen from electrolysis is dominated by two factors (1) the cost of electricity and (2) capital-cost recovery for the system. A third cost factor—operation and maintenance expenses (O M)—adds perhaps 3 to 5 percent to total annual costs. The electrochemical efficiency of the unit, coupled with the price of electricity, determine the variable cost. The total capital cost of the electrolyzer unit, including compression, storage, and dispensing equipment, is the basis of fixed-cost recovery. 

In order to lower the capital cost of the electrolyzer plant, it is necessary to operate at as high a current density as possible, i.e., often more than 500 mA cm Some commercial electrolyzers run at a current density as high as 3000 mA cm The drawbacks are a greater cell resistance, the need for a... 

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