Meet the team

Key Contacts

Key Contacts

Nigel Tate


Nigel has been with TNEI since 2002 and has been a constant member of the management team which has seen TNEI transform from a fledgling renewables operation in the North East of England to an international, multi-site, employee owned, thriving and diverse specialist consultancy that it is today. He is delighted to be leading such a talented team of specialists and experts in their field.

Nilanga Jayawarna

Resources & Operations Director and Director of TNEI Group and             Director of TNEI India

Nilanga is the Operations Director of TNEI Services Ltd. She is an Electrical Engineer who is based in our Manchester office and has a broad range of experience in people and project management, power system studies and grid code compliance.

Dieter Gütschow

Director of Client Strategy & Policy and Director of TNEI Africa

Dieter is Director of Strategy and International Business at TNEI, as well as Director for TNEI Africa.  He has more than 25 years of electrical engineering, international project management, and consulting experience across various areas of the electrical industry including renewable energy generation, transmission, and distribution. 

Mustafa Kayikci

Director of Connections

Dr Mustafa Kayikci is a Principal Consultant at TNEI, whose core skills are the modelling of power system equipment and transmission/distribution network analysis, with over 10 years of experience. Mustafa holds a PhD in electrical power systems from the University of Manchester and a First Class Honours Degree in Electrical and Electronic Engineering.

Stephanie Hay

Director of Networks & Innovation and Director of TNEI Ireland

Stephanie is Director of the Networks & Innovation Team at TNEI.  She is a Chartered electrical engineer with 14 years of experience in the power industry, including a 4-year PhD on active network management and control of distribution networks and 10 years as a power system consultant.

James Mackay

Director of Environment & Engineering

James is Director of the Environment & Engineering Team, which provides support in relation to EIA, acoustics, GIS, shadow flicker, glint & glare and design on a range of energy generation, storage and transmission projects.

Dearbhla O’Brien

Country Manager and Director of TNEI Ireland

Dearbhla is Country Manager and Director of TNEI Ireland. She has over 13 years’ experience within the energy industry in Ireland. Her experience spans power system planning and operation, with expertise in network modelling and power system analysis. Dearbhla has worked in a diversity of roles, both technical and commercial, leading numerous detailed technical and economic analysis of some of Ireland’s largest infrastructure developments.

Jim Singleton

Environment & Engineering Team Manager

Jim carries out environmental noise propagation modelling, assessment and reporting for a wide range of sectors, with particular expertise in industrial, commercial and energy projects. Recent projects of note include energy from waste plants, capacity mechanism schemes, port activities, electrical infrastructure and road, rail and aircraft noise.

Gary Preston

Connections Team Manager

Dr Gary Preston is a Power Systems Engineer with extensive experience in power system modelling and analysis.  Gary specialises in the area of electromagnetic transients and has carried out numerous fault, switching, and lightning studies using EMTP-ATP and PSCAD software to investigate fast and very fast transient phenomena.  He also has experience in the areas of power quality and power systems dynamics.  Gary is also a regular peer reviewer for several prestigious international research journals and conferences.

Rieghard Vermaak

Rieghard Vermaak

Country Manager of TNEI Africa

Rieghard is a versatile electrical engineer with a broad background in power systems and renewable power generation. He spent more than 7 years working for South Africa’s utility company, Eskom, in the Distribution Operations and Maintenance department where he fulfilled various engineering and management roles. Thereafter he joined RINA where he performed renewable energy advisory services for clients in Sub-Sahara Africa and Australia. Since joining TNEI in 2021, Rieghard specialises in performing grid code compliance services and providing strategic grid connection advisory services. This includes renewable power plant modelling and grid code compliance simulation studies, power quality assessments, model validation studies, protection settings reviews and testing support.

Gorby George

Software & Solutions (IPSA) Team Manager and Director of TNEI India

Gorby is the IPSA Lead and a Senior Consultant within the Network and Innovation Team, based in Manchester. He has over six years of experience working closely with Distribution Network Operators (DNOs) across the UK on many innovation & Business-As-Usual (BAU) projects. He has a diversified skillset which includes experience and expertise in project management, power systems studies and analysis and scripting in multiple coding languages.

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