Hydrogen Tech World April 2025 | Page 28

[ green DRI ]

RES generation or excess RES generation, overproduction of green hydrogen is needed to cover times when RES generation is insufficient. Appropriate storage systems – for electricity or hydrogen – must be added, depending on local conditions, supply security, and system efficiencies and losses. Hydrogen storage costs vary by pressure and technology, so a BESS is used as the most comparable storage system. Calculations compare different RES generation profiles for a constant annual production of 53,404 ± 500 t H 2

.

Green hydrogen production with minimum capital expenditures is listed in Table 3, considering the different energy systems. Spain and Oman cases are on-grid, with the possibility to receive power from the grid with a carbon footprint. Regions that require green power to be produced regionally and simultaneously can produce hydrogen with high electrolyzer installations when power is available or by installing BESS or other long-duration storage facilities to shift green power according to demand. Modern electrolyzers operate within 40 – 100 % of rated power without major negative impacts on lifetime to limit power storage installations. with a 6-hour capacity can reduce wind generation and electrolyzer installations by 130 MW each – saving 1.7 % on the entire energy system and 5.9 % on initial investment. For Oman, a 400 MW BESS with a 4-hour capacity reduces electrolyzer installations by 110 MW, saving 2.1 % overall and 5.1 % short-term.

Figure 3 shows electrolyzer utilization. Each data point represents two electrolyzers with 20 MW of capacity. Some operate nearly at baseload with over 8,000 hours and fewer than 50 stops. Most operate cyclically, with fewer than 6,000 hours and over 200 stops annually, due to the high PV share( see green curves, Figure 3 left & center). Installing a BESS increases operating hours beyond 6,000 and reduces stops by over 31 % in Spain and 16 % in Oman – resulting in more than 20 hours per stop. Larger BESS could enable full baseload operation but would require a high additional investment of $ 1,570 million for Spain and $ 1,087 million for Oman, plus extra RES installations( 210 MW PV and 160 MW wind for Oman). This would allow electrolyzers to operate over 1,000 hours per stop in Spain and over 2,000 hours per stop in Oman.

To produce green hydrogen for Spain and Oman, a RES generation mix of 60 ± 10 % with 1,500 MW and 1,450 MW, respectively, resulted in the lowest capital expenditures. Both cases require 600 MW of electrolyzer capacity. Maintaining an annual production of 53,404 t H, adding a 200 MW BESS 2

For Australia’ s off-grid energy system, the priority is the reliable operation of a mine with an annual peak demand of 168 MW. Excess power can be used for hydrogen production. If hydrogen production exceeds 53,404 t H, a steel plant with 1Mt DRI

2 annual capacity can be considered, or hydrogen

Table. 3. Energy systems and estimated costs for the production of green hydrogen Country

Spain

Oman

Australia

Electrolyzer Capacity [ MW ]

RES Installations [ MW PV / MW Wind ]

BESS [ MW / h ]

Green H 2 Share

[%]

CAPEX [ M $]

28 Hydrogen Tech World | Issue 21 | April 2025