Long-term, cost-efficient security of supply

Christopher Steinwachs, Vice President Vanes & Blades at Siemens Energy Gas Services, is Deputy Chairman of the FVV. In this interview, he explains the role that gas turbines and other turbomachinery play in the energy mix of the future.

Text: Mathias Heerwagen | Pictures: Sarah Kastner, Dirk Lässig

Mr Steinwachs, what kind of challenges does the energy transition hold for Siemens Energy, and what has changed since our last conversation four years ago?

First of all, the gas turbine market was in decline at the beginning of this period. In 2020 and before, fewer than around 80 gas turbines with an output of more than 100 MW were sold globally. Production capacities were adjusted worldwide, but we urgently need them again today. The global expansion of renewables such as photovoltaics and wind power has progressed massively during this period, and with it the residual load requirement, meaning that conventional power plants have to step in. In most countries, it is gas-fired power plants that fulfil this function, although - depending on the country - nuclear power plants are more and more taking over again. Today, we have around 150 gas turbines above 100 MW per year on the market.

Otherwise: We are no longer building coal-fired power plants, but the electricity grid business is becoming increasingly important, including for offshore wind farms, and we are expanding the hydrogen business, as well as the wind power division with Siemens Gamesa. We are gradually converting our gas turbine portfolio to run on greenhouse gas-neutral fuels such as hydrogen.

Siemens Energy has been working on switching to partial or full operation with hydrogen for some time now. What progress have you made?

Depending on the type of gas turbine, we already offer the option of adding up to 70 per cent hydrogen. However, burning 100 per cent hydrogen is a major challenge. The fuel has a lower volumetric energy density, we have to feed much more fuel gas into the turbines, there are very high flame speeds - taking all this into account and realising it reliably in a large turbine is very complex. But: In France, Siemens Energy has carried out the first operation with 100 per cent hydrogen using a ›dry low NOx‹ combustion system without adding water as part of a test plant with an SGT-400 gas turbine, which produces around 12 MW of electricity, and that is a great success.

As a member of the European Turbine Manufacturers Association (EUTurbines), Siemens Energy has committed to realising 100 percent hydrogen combustion in gas turbines by 2030. What is the current status?

I am firmly convinced that we can keep to the schedule. We can already offer our large HL-class gas turbines with a 50 per cent hydrogen admixture and are also building gas-fired power plants that are 100 per cent ›H₂ ready‹, where the plant is fully equipped from the outset to be able to burn 100 per cent hydrogen at a later date. Whether corresponding hydrogen pipeline networks and the required quantities of sustainable hydrogen will be available by then is another question. Power plants are planned for an operating period of around 30 years, which means that power plants being built today will have to plan for the conversion to hydrogen. We expect the first gas turbine models with 100 per cent hydrogen combustion to be commercially available on the market in the next few years.

In addition to maximising efficiency, what are other important research and development goals, and in what ways have they changed in recent years?

Most large gas turbines today are still sold for use in combined-cycle gas and steam power plants (CCGT). These turbines run for quite a few hours a year, and in such plants a difference in efficiency of 0.5 per cent makes a huge difference over the long term - so efficiency remains very important. However, there are also gas turbine power plants for peak load applications that are only used for a few hundred hours a year, for which, for example, a high level of reliability during start-up is extremely import. Many gas turbines today are also often operated in the part-load range, so the aim is also a good part-load efficiency, which we must guarantee and prove during the acceptance process. In cyclical operation, the loads are high: the turbine runs up to base load, down to part load, cools down again, so the design and service concepts have to be adapted accordingly. These are all new requirements that did not exist to this extent a few years ago.

As long as hydrogen is not available in the necessary quantities and natural gas continues to be burnt, carbon dioxide will be produced. Is CO_2- capture already technically feasible and where do you see opportunities and challenges?

The CO₂ can be separated from the fuel before combustion and then used as a sustainable fuel, for example hydrogen. In post-combustion capture, the carbon dioxide is then injected into the ground or stored in caverns, as is already the case in the Netherlands. This is also being researched on a large scale in the USA. However, this is technically complex, consumes a lot of energy and therefore reduces overall efficiency.

Is there a better technical solution?

Together with 8Rivers, a technology company in the USA, we are developing a new type of turbine that works according to the Allam-Fetvedt Cycle. In this cycle, CO₂ is the actual working medium and not steam, as in a steam turbine. Natural gas is burnt here with pure oxygen, expanded in a turbine and the combustion products are only CO₂ and water. Excess CO₂ and water are then captured in liquid form and no climate-damaging gases are released into the atmosphere. I am very confident that this technology will become established in the future.

Can Industrial Collective Research contribute to this?

You have been Deputy Chairman of the FVV Board since the end of 2019. What has your experience been like so far and what are your hopes for the future of the FVV?

Many topics have been added to the FVV in recent years, and the structure of the project groups has been adapted accordingly. In the automotive sector, the focus is now also on battery electric powertrains, hydrogen combustion and e-fuels, and many companies are participating in order to bring in their topics and demonstrate their openness to technology. That's great! And this openness to technology pays off for the member companies. Siemens Energy, for example, is looking at how hydrogen combustion can be optimised or how materials behave in a hydrogen atmosphere; this is very important input for further product development.

Where can FVV still improve?

We need to communicate the benefits of Industrial Collective Research even better, right up to the very top in the companies. So that it is known what research is currently being carried out and what benefits the scientific results have for a company, but also for society. There are many very good FVV studies, the FVV has adapted well, and now, from a technological point of view, we need to do a better job of highlighting the respective advantages and disadvantages of the possible options.

Contact with universities is also extremely important, but is often underestimated, even though you can recruit future staff with the students. We also need to make decisions more quickly, for example on funding applications, but unfortunately everything has become much more bureaucratic than it was a few years ago. The funding organisations are very slow to make decisions.

When we meet again in four years' time, what will have changed for the FVV?

With all the innovations and openness to technology, turbomachines still have a future in the international arena, and the FVV will continue to work on challenging projects. We now have major member companies from abroad and I am firmly convinced that we will have even more international members when they recognise the benefits of collective research. Companies are increasingly looking for R&D collaborations in order to develop products more cheaply and, above all, more quickly.

What do you think will change for Siemens Energy?

We also benefit from collective research: new products will come onto the market more quickly and we will be much further ahead with hydrogen combustion in gas turbines. I am personally convinced that we will then be able to burn 100 per cent hydrogen in the most important products, such as our F and HL classes, and the industrial gas turbines, too. I also believe that gas turbines will continue to be a very important component of the energy transition, but then decarbonised to cover the residual load, i.e. the hours and seasons when there is not enough solar and wind energy available. //