By Jacco Hogeweg
Green hydrogen is not only the key to a carbon-free energy system. In addition to being an energy carrier, it is a sustainable raw material for the (process) industry. “Think of the production of fertilizers, but also processes that require high temperatures, such as in steel plants,” says Andreas ten Cate, System Integration Program Director at the Institute for Sustainable Process Technology (ISPT). “We are now using fossil fuels on a large scale for this.”
The production of green hydrogen is technically not a brain teaser. The use of electrolysis to make hydrogen from demineralised water has been around for about a century. “The challenge now is mainly to make a jump in scale and to make green hydrogen competitive in price,” says Ten Cate. According to him, there are a number of preconditions for the necessary jump in scale (see box). “The EU and national governments must ensure that you can earn money with green hydrogen with new regulations. In addition, we need a growing capacity for offshore wind to keep the future hydrogen plants running for sufficient hours per year.”
From megawatts to gigawatts
To meet the energy needs of industry, transport, and other sectors, we need to produce enough hydrogen. The Dutch targets for hydrogen in the Climate Agreement include an electrolysis capacity of 3–4 GW by 2030. The European ambition is 40–60 GW by 2030. By way of comparison: until recently, the largest existing hydrogen plant had a maximum capacity of 10 MW. So, we need an enormous and affordable upscaling in eight years’ time.
Another condition for large-scale implementation of green hydrogen is clarity about the capital expenditure for a gigawatt hydrogen plant. What does such a plant cost? And can smart applications of advanced technologies and optimisations reduce costs to such an extent that green hydrogen becomes an attractive alternative for industry?
Hydrohub Gigawatt Scale Electrolyser project
These are the questions that formed the basis of the Hydrohub Gigawatt Scale Electrolyser project. From the end of 2018 to the end of 2021, a broad consortium (see box) led by the ISPT worked on the answer to the question of how we can produce green hydrogen in the Netherlands more cost-efficiently and on a large scale. Which electrolyser technologies have the best potential in terms of costs, flexibility, and heat recovery, among other things? Where would hydrogen plants function best in the Dutch industrial clusters? And what does a basic design for a hydrogen plant with a capacity of one gigawatt look like?
“We looked at where the plants could be located in the five Dutch industrial clusters and identified 22 potential locations,” says Hans van ‘t Noordende, Technical Project Leader at ISPT. “In consultation with industrial companies, network operators, and governments, we mapped out how such a factory fits their needs and projects, where we can extract water and electricity, how we can distribute hydrogen in the smartest way, and how we can use residual heat.”
Collaboration between industry & knowledge institutes
In the Hydrohub Gigawatt Scale Electrolyser project, the ISPT collaborated with industrial partners Dow Chemical, Gasunie, Nobian, OCI, Ørsted, and Yara, and knowledge institutes TNO, Imperial College London, TU/e, and Utrecht University. Part of the ISPT’s Hydrohub Innovation Program, the project was co-financed by TKI Energie en Industrie, part of the Energy Top Sector, with the additional subsidy ‘TKI-Supply’ for Top Consortia for Knowledge and Innovation (TKIs) from the Dutch Ministry of Economic Affairs and Climate.
First, the collaborating parties focused on a technical elaboration of a state-of-the-art hydrogen plant that could be built today. “The goal was to get the capital investments as low as possible,” says Van ‘t Noordende. “It is clear that we will not achieve the desired result with the application of current technology on a megawatt scale. A huge floor space would be required and the total construction cost for a factory could amount to €1.4 billion. The capex and footprint must therefore be reduced.”
Advanced design for AWE and PEM plants
Engineers from different areas of expertise then set to work on a design for an advanced, energy- and cost-efficient factory. “We conducted consultations with suppliers, among other things, to get a clear picture of the direct and indirect costs, including unforeseen costs,” says Ten Cate. “That gave us a really realistic reference.” The engineers worked out the design for both an alkaline-technology (AWE) plant and a plant with electrolysers using proton-selective polymer membranes (PEM).
The calculation yielded a promising result. “In 2020, we already made a first design for an electrolysis factory,” says Van ‘t Noordende. “Since then, we’ve honed the design, nearly halving capital expenditures.” The expected total investment is now €730 per kilowatt or €1,580 per kg of H2/d for AWE and €730 per kilowatt or €1,770 per kg of H2/d for PEM. The total investment for an advanced gigawatt-scale AWE electrolysis plant in 2030 has been reduced from €1.4 billion to €730 million through optimizations. And a PEM hydrogen factory does not cost €1.8 billion, but €830 million.”
The substantial cost reduction of almost 50% is achievable thanks to savings in all parts of the plant with various innovations in the electrolysis stacks and by scaling them up to larger units. For example, both types of electrolysers use advanced electrode materials and thinner materials than in the basic design of 2020. The number of cells per stack has also been increased. The AWE stacks have 335 cells with a total capacity of 20 MW. The PEM stacks use half that power with 310 cells. “The anodes contain lower amounts of iridium, which means that we are less dependent on this scarce raw material for the construction of hydrogen factories,” says Van ‘t Noordende. The electrolysers form modular units of 160 MW (AWE) and 40 MW (PEM). “This modular structure makes it possible to scale up factories cost-effectively.”
Skipping H2 compression step
Another improvement in the design was to increase the pressure in the AWE electrolysers to 5 bar, Van ‘t Noordende reveals. “That way we skip the first expensive step of hydrogen compression. Hydrogen must then be further compressed to 30 bar for the end users. For PEM, that pressure of 30 bar is already there, so extra compression is not necessary there, which makes a PEM installation slightly more efficient. But both types of stacks have nearly 80% system efficiency.” The AWE stacks operate at a temperature of 100°C, while in the PEM it is at 70°C. The design also takes into account heat recovery from the cooling water. Regional heat networks could make use of this.
The engineers are also taking advantage of opportunities to optimise the electrical installations of the hydrogen plant. A cost-effective layout has been designed with 380 kV/66 kV transformers in combination with low-voltage transformers and active control semiconductor rectifiers called insulated-gate bipolar transistors (IGBTs). That is in accordance with the network requirements. The transformer and rectifiers form independent e-houses, which makes the design extra compact.
Further R&D, pilots and demos
On an area of approximately 10 hectares, the hydrogen plant houses everything needed for electrical installations, electrolysis, purification, and compression to supply hydrogen in line with the fluctuating supply of sustainably generated wind energy in accordance with the demand of the end users. Nevertheless, necessary R&D, pilot and demonstration projects are still needed to implement technological innovations that allow further cost reductions. “The time is running out for this,” warns Ten Cate. “If we want to have these hydrogen plants operational by 2030, new technologies must be commercially available by 2026.”
A major advantage of the Hydrohub Gigawatt Scale Electrolyser project is that there is a concept or design on paper. In fact, the project team has even made a virtual reality model and animation film that allows you to walk through the plant, as it were. “We are showing that such a hydrogen plant can really become a reality,” says Ten Cate. “Because we worked together within a broad consortium of diverse experts, our design and calculations are very expressive.”
Ten Cate noticed a great enthusiasm among the project partners to create a smart and feasible concept or design. “All parties have an enormous need to find out what the hydrogen plant of the future will look like, so that they can focus on that with their products and services.” Each partner contributed its own specific expertise so that the puzzle could be worked on together. “You don’t come across such a broad consortium of industrial companies and knowledge institutions very often.”
About the ISPT
As an energetic and open innovation platform for sustainable process technology, the Institute for Sustainable Process Technology (ISPT) connects stakeholders from different sectors and disciplines. Together with them, the ISPT innovates and pioneers to accelerate a more sustainable industry. Industry is an essential player in achieving a circular economy in 2050. It is a driver and connector in the reuse of residual and waste flows, the integration of electricity demand, the development of hydrogen as a feedstock and energy carrier, and so on. Together with its partners, the ISPT is committed to the transition to a circular and carbon-neutral process industry in 2050.