With green hydrogen towards an energy-independent and environmentally responsible society

19 Aug, 2019
With green hydrogen towards an energy-independent and environmentally responsible society

Increasingly stringent demands to cut emissions of carbon dioxide and reduce the use of fossil fuels, coupled with growing energy needs, call for the construction of numerous new electricity generation facilities that utilize renewable energy sources – RES (hydroelectric, solar, and wind power plants). The problem these technologies have in common, however, is their dependence on the weather; and this is the cause of varying electricity generation outputs, which often fail to match the actual energy needs of consumers. At the same time, there is also a growing need for an effective and reliable way of storing short-term excess electricity and putting that electricity to use during times of market shortages.

One of the key solutions for a longer-term or interseasonal storage of large amounts of electricity is to convert it into hydrogen. This hydrogen can be put into existing gas networks, stored and converted back to electricity during times of increased demand, or used as an industrial gas. Systems for converting electricity to hydrogen are called Power-to-Gas (P2G) systems.

In recent years, HESS has grown to become the country's leading company in terms of building multipurpose facilities for generating electricity from renewable energy sources, specifically water, and will continue to fulfill its mission of generating electricity and to drive further growth by developing green and sustainable energy solutions, including pilot projects in new areas of operation such as production and use of hydrogen, among others. In the future, HESS is going to go beyond being merely a developer of new renewable energy sources; by liaising with various knowledge and economic institutions and through active involvement in research projects, we seek to make our contribution to new development activities and investments with respect to meeting Slovenia's goals in terms of the proportion of RES in the gross energy consumption and transition to a zero-carbon society.

Cooperation with the Jožef Stefan Institute and the Faculty of Mechanical Engineering of the University of Ljubljana

This July, HESS signed an agreement with the Jožef Stefan Institute (IJS) on co-funding the implementation of the project "Optimization control of an energy-to-hydrogen converter in connection with a hydroelectric power plant". In a public call for the co-funding of research projects for 2019, which received a total of 781 entries, the project was selected for co-funding by the Slovenian Research Agency (ARRS). The project implementation period is limited to three years, where 25% of the funding will be provided by HESS, and the remaining 75% will be secured in grant funds by the ARRS. The project was initiated based on an idea that the company HESS came up with in response to two key challenges we face: how to transition to a zero-carbon society as quickly as possible, and how to adjust electricity generation outputs to increasingly more complex changes in the national power grid.

In the first stage of the project, the aim is to apply domestic know-how to develop a simulation model for P2G system optimal control and to engineer a process system for producing green hydrogen in connection with a hydroelectric power plant as an electricity generation source. In doing so, the focus will be on achieving the highest possible level of energy- and cost-efficiency of hydrogen production, which can only be accomplished by finding the optimal way to control and operate the P2G system.

Mr Boštjan Pišotek, project manager at HESS: "At HESS we are confident that this project will significantly speed up further development and deployment of hydrogen technologies across Slovenia, bearing in mind that Slovenia, generally speaking, lags behind some of the most advanced European countries, particularly Scandinavian. It should be noted that the practical introduction of hydrogen technologies is also part of the European strategy in the areas of energy and green transport." As highlighted in the most recent, June 2019, report by the International Energy Agency (IEA): "As an energy carrier, hydrogen will make renewable energy sources more meaningful and important. For us to have a clean, reliable and sustainable energy future, it is vital we tap into its potential as soon as possible."

Based on results obtained in the simulated environment, the second stage will involve the implementation of a pilot project at one of the hydroelectric power plants on the lower course of the Sava. Serving as a demonstration project and example of good practice, such implementation will be an important step towards strengthening the broader national interest in deploying hydrogen technologies. The project involves and interconnects two spheres – research and economy: firstly, process control and optimization technologies, and secondly, the issue of efficiently storing electricity generated from renewables – both for the purposes of power grid balancing. Among others, the project will open a new specialized multidisciplinary research and development course seeking to study the potential benefits of using and optimizing a P2G system in connection with a hydroelectric power plant and to develop an optimization methodology.

Apart from securing a competitive and green hydrogen production, establishing a suitable transmission and charging infrastructure is clearly going to be crucial in the years ahead. Hydrogen prices for consumers very much depend on the size of the charging station network and frequency of use or consumption of hydrogen.

In development projects involving hydrogen technologies, cooperation between sectors is important for achieving as efficient an implementation as possible of what is known as the green energy policy. Mr Boštjan Pišotek, HESS: "Introduction of hydrogen technologies is in the interest of not only HESS but lately also of Slovenia's other major energy companies. Together with the companies HSE, ELES and PLINOVODI, we have already begun cooperating in a broader project of converting excess electricity to hydrogen and its reuse. Built around intersectoral cooperation, the project brings together the interests of Slovenia's energy companies to implement hydrogen technologies across the energy, transport and industry sectors. By doing so, we seek to fill the gap in storing green energy, that is, energy that is generated from renewable energy sources, and to allow its further utilization."

As an environmentally responsible company, we are fully aware of the importance of Slovenia's shifting to renewable energy sources as quickly as possible and of all the challenges and opportunities in the areas of environment and energy that lie ahead of us in the coming decades, which is why we are going to make every effort to establish green systems that will comprehensively interconnect electricity generation from RES with efficient electricity storage between seasons. By building new hydroelectric and solar power plants in combination with using hydrogen technologies for storing energy, we can make a significant contribution to meeting the set goals of having a clean, reliable, competitive and independent energy future and, in turn, of securing sustainable development and a good living environment for our posterity.

What essentially is a P2G system optimal control simulation model?

It is a control system which coordinates the operation of the process system for converting electricity to gas (P2G system) based on the currently available hydroelectric power plant capacities and the conditions in the power grid.

The control system takes into account the current conditions in the power grid (presence of energy surpluses or shortfalls), hydroelectric power plant's generation capacities (water level in the reservoir), fill level of the hydrogen storage, and state of the fuel cell and electrolyser, on the basis of which it then automatically determines the direction of the energy flow and the operation mode for the fuel cell and electrolyser.

For this to work, the control system must be connected (integrated) with the power grid information system. It receives electricity production or storage requests from the power grid information system, and sends back to the power grid information system responses on the actual production and storage capacities.

The control system can also be input with economic criteria to help determine which mode of operation to choose. Economic criteria include electricity prices and costs of changing the mode of operation of the fuel cell and electrolyser system.

The system described here is useful not only for storing short-term excess electricity and generating electricity during shortfalls but also for providing ancillary services such as cold reserve. Systems incorporating fuel cells are characterized by extremely fast startup times – in the duration category of one minute.

The development of a P2G control system will establish a comprehensive model that will cover the utilization and storage of excess electricity until being delivered to the consumer – with a preset delay.


Green hydrogen = hydrogen produced from RES

Water sources are the most suitable renewable energy sources in Slovenia.

Slovenia has harnessed roughly one-half of its hydroelectric potential.

To meet its climate goals, Slovenia will need to make building large hydroelectric power plants a priority for the decade ahead.