Our Leaders

Meet the Severn Trent Green Power leadership team

Christer Stoyell

Christer Stoyell

Managing Director


Christer brings a wealth of leadership, transformation, and industry experience to his role as Managing Director at ST Green Power. Before joining ST Green Power, Christer was Director of Strategy and Transformation at Severn Trent where he was responsible for corporate strategy including the company’s plans for renewable energy, carbon reduction, sustainability, and growth.

Christer has also held leadership roles at Capita Energy Services and Npower. While at Capita, Christer oversaw the design and build of the operating model for a new UK grid-scale battery storage business. With many years in the energy sector, Christer has led sustainability and carbon net zero transformations for FTSE 100 and DAX 30 companies, both in the UK and across Europe.

Andrew Simm

Andrew Simm

Operations Director


Having worked in the Renewable Energy industry for more than 11 years, Andrew brings a wealth of experience to his role as Operations Director. Responsible for all operational aspects of the business and delivery of its strategic aims, Andrew leads a team of engineers and operatives delivering daily food waste and renewable energy solutions.

Before joining ST Green Power in 2022, Andrew previously worked as part of the commercial team at Agrivert, where a key part of his role was exploring development opportunities across the world, including China, Hong Kong, Canada, New Zealand, and the UK.

Andy Starkey

Andy Starkey

Commercial Finance and Performance Manager


A CIMA qualified accountant, Andy manages financial performance at ST Green Power. Andy started his career at Bosch Group working in the UK and Germany. He then made the move into the energy sector, and worked at Npower for four years, overseeing pricing of gas and electricity and managing sales budgets for the domestic energy division.

Prior to his role at ST Green Power, Andy spent three years at Severn Trent as a financial business partner for the commercial teams. He then stepped across into the ST Green Power business where, today, he is responsible for accounting, financial planning and analysis, energy policy, and incentives assurance.

Nicky Kerridge

Nicky Kerridge

QEHS Director


Bringing a wealth of compliance, risk, and assurance experience to her role as QEHS Director, Nicky leads a team of experts to ensure we effectively operate in-line with our regulatory and legal requirements and deliver on our audit and assurance commitments.

Nicky is also responsible for managing our environmental permitting and our ISO framework, plus she oversees the health, safety, and wellbeing of our people.

Prior to joining ST Green Power, Nicky spent 15 years in the energy sector, working for Npower as Head of Operational Compliance and Assurance, where she delivered the compliance strategy across the domestic and business customer portfolios.

Farryad Ishaq

Farryad Ishaq

Strategy & Business Development Director


Farryad joined ST Green Power in 2014, however his passion for waste recycling and renewable sources began at university when he completed a PHD in Anaerobic Digestion. While there, Farryad was sponsored by Severn Trent to complete doctoral research on the subject, which lead to him starting work at the company as an Anaerobic Digestion Specialist.

In that time, he has worked in several key roles across the company and has been instrumental in the growth of the Green Power business. Farryad moved into the role of Strategy & Business Development Director in December 2021 and is responsible for driving business development and growth.

Gemma Mcmullen-Leach

Gemma Mcmullen-Leach

HR Business Partner


As HR business partner, Gemma in an integral part of the leadership team at ST Green Power. Passionate about people development, Gemma works alongside our leaders, teams, and key stakeholders, to shape and implement people strategies and programmes that support the development of every member of the Green Power team and strengthen our business, both now and in the future.

Gemma started her HR career working for Sainsburys, where she worked in a variety of roles for 16 years. She then moved into the Aviation industry and then onto the Automotive industry, where she worked for YASA – a manufacturer of motors for electric vehicles, before joining ST Green Power.

Naomi Thomas

Naomi Thomas

Assistant to Directors


Naomi joined the ST Green Power team in 2020 and currently provides executive support to several of our directors, as well as coordinates some of our key projects and events throughout the year. Naomi has more than 10 years’ experience supporting directors and senior managers over various industries.


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