About us

Do you know any athletes who are among the best in the world in all sports? It’s not likely. And what is true for athletes also applies to recruitment consultants. After all, nobody can have detailed knowledge in many industries simultaneously, be on the cutting edge of developments and also be able to draw on an extensive and in-depth candidate network. That is why we deliberately focus exclusively on the energy sector. And in all modesty, we really know what we’re doing here. We have successfully completed more than 300 projects over the past seven years. The experience we have gained from this and our network greatly accelerates the search for candidates: While others are still trying to understand the task, we are already delivering the first results.

As helpful as knowledge of the industry and a great candidate network are however, they do not replace the need for the curious listener. After all, the decisive factor is often hidden behind what is obvious. This applies to the task presented by our clients as well as to the selection of candidates. We are well aware of our responsibility to our clients in this regard. Our pursuit of excellence extends to all the process steps in our consulting projects and serves only one purpose: finding the best candidates and rather than the second best. Maximum discretion and confidentiality as well as great sensitivity in dealing with candidates and companies are a matter of course for us.

Senior Consultant

Ulf Gissel

Ulf Gissel is a senior consultant at Callidus Energie. He has 10 years of experience in various management functions in the financial sector and was most recently managing director of a service provider for drinking water hygiene. Here he was able to build up an extensive network, including with energy suppliers. Mr. Gissel is a connoisseur of the IT industry, always interested in a wide range of topics and up-to-date with the latest technological developments. It is only consistent that he is our expert for positions in the field of digitalization and IT at Callidus Energie.

Mr. Gissel is also an enthusiastic networker in his private life and puts his talents to good use. As a freelance editor, he is regularly booked by major game publishers and film studios, so that he has already been able to interview numerous big names in the games as well as the film industry.


Florian Heilmann

Florian Heilmann is a consultant at Callidus Energie. As a psychologist (M.Sc.), he supports the team with his expertise in personnel psychology. Methodically, Mr. Heilmann deals in depth with personality diagnostics in interviews and questionnaires. Mr. Heilmann oversees the focus on smart meters and thus accompanies important players in the energy industry on their way into a digital age.

"The digitalization of the energy industry coupled with growing challenges for personnel are a dynamic mix. Callidus Energie has made it its mission to shape the energy transition."

Partner, Managing Director

Jonathan Lichter

Jonathan is a founder and partner of Callidus Energie. While studying business administration specialising in business informatics at the University of Mainz, Mr. Lichter started working in the field of executive search at a leading recruitment consultancy. In the last six years, he has held challenging mandates in the areas of sales and digital transformation. His solid network now ranges from managers to strategists to highly specialised top performers in the energy sector.

Jonathan is also interested in futuristic topics in his private life: as a “digital native” he passionately pursues all sorts of technological trends and developments. He is thus not only responsible for all IT topics at Callidus, but also plays a decisive role in the company’s development.


Jasmina Rope

Jasmina Rope is a consultant at Callidus Energie. During her studies, which focused on sociology and law, Ms. Rope discovered her passion for working with people. In our team, Ms. Rope is a competent contact person for employment law as well as contractual issues.

Outside of her academic career, Ms. Rope also focuses on legal issues and social phenomena. In her private life, the young consultant is enthusiastic about forensics and knows how to use her investigative mind for interviews and research. On top of that, Ms. Rope enjoys playing soccer and trying out new cooking recipes in the kitchen.

Partner, Head of Aptitude Testing

Ralf Sundermeier

Ralf is a partner at Callidus Energie who is responsible for the development and application of selection procedures that are based on aptitude diagnostics. A qualified psychologist and state-certified business economist, Mr Sundermeier has more than 10 years of management experience; among other things, this includes serving as the human resources manager of a large German bank. Thanks to his many years of experience as a consultant and coach, he has extensive experience in personnel selection, overseeing transformation processes and developing high-performance teams.

Partner, Managing Director

Ron-Arne Sydow

Ron-Arne is a founder and managing partner of Callidus Energie. The graduate business economist already gained his first entrepreneurial experience in his youth and has been working in recruitment consulting for over ten years. In addition to his top management level positions, he supervises mandates in the area of decentralised energy solutions, where he maintains an intensive network. His area of special interest is aptitude diagnostics. He is a keen observer of the processes of change in the energy sector and is a regular speaker on personnel policy topics.

His personal passions are having discussions about social and political issues as well as playing the piano. He is an enthusiastic snowboarder and looks forward to those cold winter days just like some of his clients.

Head of Office Management

Katrin Zoller

Katrin supports the partners in the operational area and takes care of all organizational tasks. She is the contact person for many administrative topics, such as Marketing and accounting.

She has worked as a secretary and project manager in law firms and advertising agencies. With experience from various fields and her studies in business administration (FH) she successfully steers large and small projects.