Jonathan Brearley leaves Ofgem while Terna Energy, Verlume and Eneco all welcome new appointments in the chief executive hot seat
Europe has seen a wave of leadership changes across its energy sector. Shifts in structure for UK energy regulator Ofgem, renewable companies TERNA ENERGY and Eneco, and tech company Verlume signal a broader shift as companies and regulators position themselves for the next phase of the energy transition.
Ofgem chief executive Jonathan Brearley will be stepping down from his role at the end of March to take up the position of Permanent Secretary at the UK government’s Department for Energy Security and Net Zero.
Brearley has decades of leadership experience in government and the energy sector, having led the development of the Climate Change Act as the Head of Office of Climate Change, and oversaw reform of the electricity market at the then Department of Energy and Climate Change.
At the Department for Energy Security and Net Zero, he replaces Clive Maxwell who has served as Interim Permanent Secretary while a full external recruitment process was run.
Ofgem’s Gas and Electricity Markets Board will initiate a formal search process to appoint a permanent successor. In the interim, Tim Jarvis, currently the Director General for Markets, will serve as acting chief executive.
Brearley said his time at Ofgem “has been defined by the mission of protecting consumers and navigating the complexities of the UK energy transition. I am proud of what the team there has achieved, and I carry these lessons with me as I move into this new role.
“Working alongside the Secretary of State, Ministers and the dedicated civil servants at DESNZ, I look forward to continuing the department’s focus on bringing down bills and delivering clean, homegrown power.”
While with Ofgem, Brearley drove progress towards the government’s clean power ambitions, with notable achievements which include innovative regulatory reforms to infrastructure, the Accelerated Strategic Transmission Investment initiative, a major grid overhaul, and the creation of NESO.
Mark McAllister, GEMA and OFGEM Chair said: “While we are sad to see him go, we are proud that the CEO of Ofgem has been chosen for such a pivotal role in government. We wish Jonathan the very best in this next chapter and look forward to continuing to work together as we deliver a successful energy transition for consumers.”
Brearley added: “I am confident that Ofgem is in excellent hands with Tim alongside the wider executive committee and well-positioned to continue delivering on its mission to protect energy consumers now and into the future, as we advance through the energy transition.”
Aristotelis Chantavas joins Terna
Manolis Maragoudakis, chief executive of Terna, will step down after three decades leading the company. Aristotelis Chantavas, formerly Head of Europe at Enel Green Power, will become the new CEO.
Maragoudakis will step down on March 30, with Mr. Chantavas taking over on the same day. A structured transition process is in place to ensure continuity and a smooth handover of responsibilities.
Terna Energy in a release says that Maragoudakis has been instrumental in its growth, serving as CEO since the company’s establishment in 1997.
In 2025, Terna was wholly acquired by Masdar, becoming its platform for long-term development in Greece and across Eastern Europe. Terna is now targeting an operational portfolio capacity of 6GW by 2030, supported by Masdar’s long-term capital and global expertise.
Chantavas will assume the role of CEO, bringing extensive experience of the international renewable energy sector and a strong presence within the European energy landscape. Chantavas previously served as Head of Europe at Enel Green Power and as President of SolarPower Europe, where he played an active role in shaping European initiatives for the development of renewable energy.
Maragoudakis said: “With the completion of nearly thirty years at TERNA ENERGY, a meaningful cycle of creation comes to a close for me.
“I feel proud of what we have collectively achieved, starting from the early and uncertain days of the renewable energy market to its current maturity. I would like to sincerely thank all the people who stood by me throughout these years and worked with knowledge, perseverance and a strong sense of responsibility.”
Chantavas said: “I assume the leadership of TERNA ENERGY with a strong sense of honour and responsibility, at a time when the company possesses solid foundations, deep expertise and highly experienced people in the sector.”
Terna targets 100GW global clean energy capacity by 2030.
Verlume strengthens leadership
Verlume, a Scottish-based developer of subsea battery energy storage and intelligent power management systems for the energy industry, has announced a transition for its leadership structure to support its next phase of global expansion.
After founding Verlume and leading the company as CEO for 13 years, Richard Knox will transition into the role of founder-CTO. In this position he will focus on customer engagement, innovation, and technology strategy, areas that have been central to Verlume’s success
David Clark has been appointed CEO and will lead the company through its next phase of international growth and operational scale. Clark brings more than 35 years of international leadership experience in the global energy sector.
He holds a degree in Electrical and Electronic Engineering from the University of Strathclyde and began his career with Schlumberger (now SLB), holding operational and management roles across Asia, the Middle East and Europe.
He has since held senior executive positions at Technip, Wood and Aker Solutions, where he served as President of UK & Africa and later EVP of the global Service Division. Most recently, Clark was CEO of Vysus Group following the carve-out of Lloyd’s Register’s energy division in 2020. He remains a Non-Executive Director of Vysus Group and serves as Convener of Court (Chair) at the University of Strathclyde.
The leadership changes also include the promotion of Robert Heron, a founding member of the Verlume team, to Operations & Engineering Director, alongside the appointment of Alan Shanks as Chief Financial Officer. These follow the recent promotion of Graceann Robertson to Sales & Marketing Manager as Verlume continues to expand its global presence.
Clark said: “Verlume has built a fantastic product and customer base that is recognised internationally.
With the company’s unique, proven intelligent power management platform now fully commercialised, I am looking forward to scaling the business internationally, as we expand our footprint across the oil & gas, offshore wind and defence markets.”
Knox added: “As Verlume enters its next stage of international growth, this transition allows me to spend more time understanding customers’ needs and continuing to provide innovative solutions. Bringing David in as CEO gives the company the leadership depth needed to scale globally while I continue to drive the innovation that has always been at the heart of Verlume.”
Hagens in CEO chair
Martijn Hagens has taken up his role as the new chief executive of Dutch-based international renewable energy company Eneco. His appointment was announced last year on 23 August.
At the time, Hagens said: “I’m grateful for this opportunity to join Eneco as its CEO, and to continue my work on matters that are important to me: reliable and sustainable energy for customers and for society.
“Eneco is a wonderful forward-looking company that’s passionate about the energy transition. I look forward to working together with the team at Eneco to accelerate the energy transition, which is of vital importance for our future and for growing our business.”
Hagens succeeds Kees-Jan Rameau, who had held the position of acting CEO since the summer. Rameau will continue on Eneco’s board, in the role of chief operating officer for Integrated Energy & Assets.
Mel Kroon, Chair of Eneco’s Supervisory Board, said: ‘We’re very grateful to Kees-Jan for stepping up to take on the role of CEO these past months, and for the success he brought to it.’
Hagens was formerly Senior Vice-President, Head Business Area Markets and member of the Executive Group Management of Vattenfall. Besides his duties within Vattenfall’s functional line organisation, Hagens was also CEO of the group’s Dutch subsidiary, Vattenfall NV.
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