Energy (excluding oil and gas) in Scotland


CMS’ first-rate renewables team is drawn from the firm's finance, corporate, construction, real estate, disputes and projects practices. It acts primarily for developers and funders on electricity transmission upgrades, onshore and offshore wind, large biomass, biogas, solar projects and public sector energy efficiency initiatives. Christine Worthington is noted for her experience of the construction aspects of renewables projects. Another name to note is Chris McGarvey, who joined from Pinsent Masons LLP, and focuses on engineering projects that often involve new and innovative technologies. Donald Cumming is also recommended.

Key clients

SSE Renewables

Moray Offshore Windfarm (East) Limited

Kincardine Offshore Wind Limited

Moray Offshore Windfarm (West) Limited

Red Rock Power

EDF Renewables Limited

Close Brothers / Muirhall Energy Limited


Northern Ireland Water

Work highlights

  • Advised SSE on sale of 49.9% stake in onshore windfarms (Stronelairg and Dunmaglass); on security and property diligence aspects of offshore windfarms (Beatrice Offshore); and on implementation of planning, consents and real estate advice on onshore windfarm (Strathy South).
  • Advising on a range of areas in the development of the offshore windfarm, including Ports and Harbours leasing and construction, offshore services such as boulder and EOD clearance contracts, corporate policies, data protection and cable array contracting.
  • Advising Kincardine Offshore Wind Limited on all aspects of the continued development, including implementation of project consents and regulatory matters.

Pinsent Masons LLP

Pinsent Masons LLP ’s energy and projects work is a key pillar of its operation in Scotland. On the corporate side, the team advises on M&A for purchasers and vendors of renewable energy assets. Elsewhere, the practice handles project finance transactions for both sponsors and banks on UK wind farm and solar refinancings. Other areas of focus include offshore wind planning, procurement and construction, energy trading and regulation, and environmental, social, and governance (ESG) initiatives. Team head Ian McCarlie acts for developers, stakeholders, funders and investors across the UK and Ireland. Kate Turner left for an in-house role at Scottish Power.

Practice head(s):

Ian McCarlie


‘Extremely strong understanding from Energy and in particular renewable markets. This has helped us build the first unsubsidised corporate PPAs of scale in UK history

‘Ian McCarlie and Ronan Lambe are absolutely top of their game in the energy space with contacts all over the industry and a pragmatic approach to landing complex negotiations.’


Key clients







Capital Dynamics

Blue Energy




Work highlights

  • Advised Tesco on all aspects of a major project to source green electricity directly from wind farms and solar parks in order to meet their 2030 zero carbon targets.
  • Advised Statkraft on the forward sale of two Scottish onshore wind farm projects (Twenty Shilling and Windy Rig) to Greencoat.
  • Advising Orsted Hornsea Project 3 (UK) Limited on all aspects of the consenting and property rights (both compulsory and negotiated) required in connection with the proposed up to 2400MW Hornsea 3 offshore wind farm off the east coast of England.

Shepherd and Wedderburn

Shepherd and Wedderburn's practice has a focus on the key sub-sectors of offshore wind, onshore renewables and storage, floating wind and tidal, and low carbon and transmission. Noted for its regulatory expertise, the team has recently been advising clients on the potential impacts of Brexit on the energy industry. Team head Clare Foster is experienced in project finance transactions in the energy and infrastructure sectors. Another name to note is Richard Turnbull, who joined from TLTDaniel Lee left for Burges Salmon LLP.

Practice head(s):

Clare Foster

Key clients

Neart na Gaoithe Offshore Wind Limited (NNG) (a subsidiary of EDF Energy Renewables Limited)

Ørsted (formerly DONG Energy Wind Power A/S)

Green Investment Group (formerly Green Investment Bank plc (GIB))

Moray Offshore Windfarm (East) Limited (formerly Moray Offshore Renewables)

Moray Offshore Windfarm (West) Limited

Simec Atlantis Energy Limited

MUFG Limited (formerly The Bank of Tokyo Mitsubishi UFJ)

ScottishPower Renewables

NTR plc

Innogy Renewables UK Limited

Forsa Energy Limited

BayWa r.e. UK Limited


Work highlights

  • Providing project financing and equity transaction advice to Neart na Gaoithe Offshore Wind Limited (NNG).
  • Advised Forsa Energy Limited on the sale of its 350MW portfolio of onshore wind projects to BayWa r.e. UK Limited.
  • Acted as sole legal adviser to ScottishPower Renewables (UK) Limited on a significant, long-term Power Purchase Agreement (PPA) with Tesco in respect of power generated at Halsary Windfarm.

Addleshaw Goddard

Addleshaw Goddard stands out for its expertise in the onshore wind sector, where it acts for a range of established developers, funders and contractors, including blue-chip clients. The corporate and finance practices remain strong in this space, with added assistance from the planning and consenting team, and litigation group. Alan Shanks is the head of the practice. Paul Minto left for an in-house role at Land and Forestry Scotland.

Practice head(s):

Alan Shanks


‘The AG practice is grounded in the reality of business. When we are supported by AG we do not find ourselves debating the minutiae of clauses. The team focus is in what is the real issue and how do we modify our position to get an agreement.’

‘Alan Shanks is our partner of choice. At the most intense and stressful phases of a negotiation he is always available and is always calm. He provides measured and pragmatic advice.’

Key clients

Red Rock Power

EDF Renewables


Point & Sandwick Power

Vento Ludens

Kilmac Energy

Gravis Capital Partners

Flotation Energy

Lloyds Banking Group

The Royal bank of Scotland

Work highlights

  • Advised Red Rock Power on the refinancing of Afton Wind Farm, a 50MW operation project in Ayrshire. Funding was provided by NatWest.
  • Advised Scotia Gas Networks plc on multiple appeals to the Scottish Government’s Directorate of Planning and Environmental Appeals concerning the listing of former gasholders on sites earmarked for regeneration.
  • Advised SSE on the different construction packages (professional appointments and main construction contracts) and interfaces relating to the project to connect Shetland to the UK’s electricity transmission system.

Brodies LLP

The renewables team at Brodies LLP often finds itself at the forefront of developments in the onshore wind, subsidy-free, tidal, hydro and heat sectors. It advises international developers and funders on contract for difference (CfD) projects, subsidy-free onshore wind and solar projects, regulatory matters and power purchase agreements (PPAs). The team is jointly led by Keith Patterson (who focuses on transactional and project finance matters), Kirsty Macpherson and Michael Stoneham. Sarah-Jane McArthur specialises in low carbon energy projects, while managing associate Claire Reid focuses on wind, hydro and anaerobic digestion.

Other key lawyers:

Sarah-Jane McArthur; Claire Reid


‘Can do attitude. Quick responding, and very knowledgeable.’

‘Great communicators.’

‘Keith Patterson assisted us in the work related to an agreement for the wind farm project and Kirsty MacPherson for the work on land connected to that project and especially the issues of crofting law that were affecting this. Both were a huge help to us and very knowledgeable in their own field, which was invaluable in the complex transaction we were completing.’


Key clients

Banks Renewables


Clydesdale Bank

Orbital Marine Power

GFG Alliance including SIMEC and SIMEC Atlantis Energy

Energy Isles Limited

Guinness Asset Management


Scottish Enterprise

Clyde Gateway

Work highlights

  • Advising Banks Renewables Limited on a groundbreaking judicial review of Contracts for Difference (CfD) Auction Round 3.
  • Advising Clydesdale Bank Limited on the financing acquisition of a biomass portfolio.
  • Advised Gresham House on the purchase of a subsidy-free solar park.

Burness Paull LLP

Burness Paull LLP handles consenting, development, construction, operation, financing, M&A and regulatory matters in the renewables sector. The firm receives referrals from City firms, as well as generating and leading matters on the ground in Scotland. Chris Gotts is the head of the team. Peter Ward focuses on energy transactions, advisory and regulatory work. Another key individual is Tamar Tammes, who is experienced in energy-related real estate matters. Senior associate Chris Horsley is also recommended. In a notable development, Neil Bruce was promoted to partner. In addition, Alasdair Sutherland , who was formerly an advocate at the Scottish Bar, joined as a partner. Craig Whelton left for Burges Salmon LLP.

Practice head(s):

Chris Gotts


‘Burness Paull are professional, responsive and most importantly can be completely trusted to deal with their work in a no fuss manner.’

‘Very good property team, which has been very responsive to various requests in relation to a large number of sites. The team are happy to stand behind their advice, and on many occasions have been proved absolutely right when tested.’

‘Neil Bruce is excellent on energy project real estate matters. He is also very client-focused and very responsive.’

‘The team have a depth of experience and knowledge across the energy spectrum and covering all applicable legal practice areas. Coupled with their commercial and collaborative approach to their service delivery, Burness Paull are a “go to” for Scottish energy transactions.’

‘Burness Paull have a “hands on” approach, meaning you receive the same level of engagement from senior team members as you do junior team members, which is reassuring.’

‘The service provided by Burness Paull is one of the best in the market.’

‘Peter Ward is extremely knowledgeable about complex energy market issues, and always able to understand any issue from both a legal and commercial perspective, using extensive experience and a strong team to provide a comprehensive, efficient response.’

‘Sophie Coffey is approachable and very knowledgeable.’


Key clients

ScottishPower Renewables

EDF Energy Renewables


Statkraft UK

Ventient Energy

Invenergy Wind Europe

Close Brothers

Fred Olsen Renewables

BayWa r.e. UK

Brookfield Renewables

Work highlights

  • Advised EDF Renewables in relation to the framework agreement, property and off-take arrangements with Tesco for the installation of on-site solar generation across 17 Tesco stores in the UK.
  • Acted for MUFG as agent/adviser to a funding syndicate of 25 lenders in relation to the £2.5bn Neart na Gaoithe (NnG) offshore wind farm.
  • Having acted for BayWa on the acquisition of the Tralorg Wind Farm in 2018, the firm advised BayWa on key development aspects of the 18MW wind farm (including property development and offtake arrangements) prior to the sale of the project in November 2019 to the Railways Pension Fund.

Anderson Strathern

Anderson Strathern has a strong track record acting for landowners on onshore renewables projects. It also handles offshore projects, most notably for Crown Estate Scotland. The firm also counts developers and investors as clients, particularly in the turbine, solar, gas to grid, hydro and biomass sectors. The team is jointly led by Martin Whiteford, Neil Farrell and Bruce Farquhar. Farquhar handles corporate transactions connected with renewable projects.


‘A strong team of property and commercial solicitors that support us across a wide variety of renewables projects in England and Scotland’.

‘Bruce Farquhar, Neil Farrell, Martin Whiteford – all are very hard working and strong members of the team that have helped us deliver internally and to end clients’.      

‘Extremely knowledgeable, approachable and very well-connected team. I recommend Anderson Strathern and the energy team to all my peers’.

‘Martin has an excellent understanding of the renewable energy and construction market in the UK’.

‘As a small developer, Martin is a key adviser to our business, he is readily available to help us across all aspects of our business and has an excellent network of contacts’.

‘Martin Whiteford has the ability to appreciate and distil large volumes of information and data very quickly and clearly. He’s also a thoroughly decent guy’. 

‘Bruce Farquhar has a wealth of experience across several sectors and has an excellent appreciation of the challenges small business face’.

‘Bruce Farquhar is very approachable and professional but has a very down to earth manner which makes him very easy to work with’.

Key clients

The Crown Estate Scotland

Bluefield Solar




Livos Energy

Elgin Energy

Thöni Industriebetriebe Gmbh

Longspur Capital

Buccleuch Estates

DHG Hydro


Buchan Biogas

Scottish Hydrogen and Fuel Cell Association


Work highlights

  • Advising Crown Estate Scotland on the development of offshore wind projects in Scottish Waters.
  • Advising Roxburghe Estate – Sunlaws Development Company Limited in relation to option and lease and ancillary documentation for the extension of the Fallago Rig Windfarm.
  • Advising Bangley Quarry Biogas Limited (Green Forty Development Limited) on the development of a major biogas project in East Lothian.


Dentons’ Scottish team works on domestic and international matters in conjunction with its global network of offices. It is noted for its experience of advising on small and mid-scale projects for developers and funders, particularly in the onshore wind, hydro, solar, marine and energy from waste (Efw) spaces. Practice head David Cruickshank, who focuses on renewables and alternative energy, is a member of the firm’s cross-practice energy transition programme.

Practice head(s):

David Cruickshank

Other key lawyers:

Allan Cairns; Bill Fowler; Paul Young

Key clients

Aggreko PLC

Blue Transmission

Canadian Solar

European Marine Energy Centre

European Energy Efficiency Fund

Goldwind Global

Hero Future Energies

Ingenious Renewables


National Grid

Work highlights

  • Advised Aggreko PLC on a new hybrid modular power station at Resolute’s Syama Gold Mine in Mali.
  • Advised St John’s Hill Wind HoldCo Ltd on the acquisition of Port of Sheerness Wind Farm in Kent.
  • Advised Beijing-headquartered Goldwind on its £21m subscription for shares in the capital of Oxford Photovoltaics Limited.

Gillespie Macandrew LLP

Gillespie Macandrew LLP handles onshore and offshore renewable energy developments, including decommissioning, repowering and refinancing, structuring of development vehicles, storage and network connections. The team works closely with members of the planning and construction, regulatory, land litigation and judicial review groups. Derek McCulloch leads the team, which includes recently promoted partner Simon Williams.

Practice head(s):

Derek McCulloch

Key clients

Rio Tinto


Viking Energy

Seagreen Wind Energy

REG Power

Energised Environments

Bespoke CIC (community wind)

Dalmore/PIP/Blyth Holdings

Ardtornish Estate

Work highlights

  • Advising on Phase 1 of Seagreen’s c.1 gigawatt windfarm scheme.
  • Advising Viking Energy on the c.450 megawatt windfarm development in Shetland.
  • Advising Dalmore/PIP on the acquisition of a 49% interest in 24 wind farms – both onshore and offshore – from EDF in a deal worth over £701m.

Harper Macleod LLP

Harper Macleod LLP continues to be strong in the UK secondary and investment markets, and is well regarded for its expertise in construction, planning and property, grid connection agreements and renewable energy projects. David Bone leads the team, which acts for funders and borrowers on the financing and refinancing of renewables projects. Omar Ali is also recommended.

Practice head(s):

David Bone

Other key lawyers:

Pamela Todd; Omar Ali


‘Harper Macleod have shown a willingness and ability to understand how our company operates. This awareness has allowed them to provide high quality legal support in different areas of our business.’

‘Pamela Todd and her team have a wide experience of negotiating renewable energy transactions and are able to provide concise legal and property advice whilst always having an appreciation for the commercial realities for such agreements.’

‘The HM team have a great mix of technical ability, commercialism, responsiveness and pragmatism when it comes to fee arrangements. They also mix this with excellent and deep energy sector knowledge which is of great value to us and our clients.’


Key clients

Fred. Olsen Renewables Limited

Forestry & Land Scotland

Aberdeen Standard Investments

Hermia Community Energy CIC

InfraRed Capital Partners

Natural Power

Abundance Investments Limited

Alpha Real Capital

EnergieKontor UK Limited

Local Energy Scotland

Work highlights

  • Advised Aberdeen Standard Investments infrastructure debt team on its loan of £63m to finance the operational 27 MW Whiteside Hill windfarm.
  • Advised Fred. Olsen Renewables Ltd (FORL) on the £400m refinancing of seven major Scottish wind farms with a combined output in excess of 420MWs.
  • Advised Abundance Investments Limited on its ethical peer-to-peer platform for a £1.6m investment in the development of three pumped storage hydro projects in Scotland.

BTO Solicitors LLP

BTO Solicitors LLP acts for a variety of clients in the renewables sector, and its work ranges from community-driven projects to projects involving international funders. The team, which is jointly led by Nicholas McBride and Jeremy Glen, sees an uptick in mandates relating to refinance transactions. The practice leverages mandates from commercial developers and operators, community renewables groups and landowners in the diversification of landed estates in wind and hydro developments. Alan Borthwick retired.

Practice head(s):

Nicholas McBride; Jeremy Glen

Other key lawyers:

Scott Wyper

Key clients

Triodos Bank UK Limited

CRF Hydro Power Limited

Turnalt Hydro Limited

Baldowrie Estate

Srondoire Wind Farmers Limited

Luss Estates Company

Allt Dearg Wind Farmers LLP

Inver Hydro Limited

Scottish Hydro Investments Limited

Greencoat UK Wind

Work highlights

  • Acted for Greencoat UK Wind Holdco Limited, a wind power developer, on the purchase of a wind farm scheme in the Highlands for £57.5m.
  • Representing Danish purchaser Eurowind Energy A/S in its £3.5m acquisition of a wind farm.
  • Representing CRF Hydro Power Limited in its acquisition of a scheme for the construction of a hydroelectric power generation facility in a competitive bid scenario with a total built-out value of £9.5m.

Davidson Chalmers Stewart

Davidson Chalmers Stewart handles contentious and non-contentious issues for developers in relation to property, commercial, corporate and regulatory issues. It also deals with planning, environmental and specialist rural business issues, such as crofting. Clients include investors and funders of renewable energy schemes. Laura Tainsh leads the team.

Practice head(s):

Laura Tainsh


‘Extremely professional’.

‘Jaqueline Cook is an outstanding asset to Davidson Chalmers Stewart; she paid our case particular attention and gave in-depth advice’.

‘Small enough to give a personalised service but experienced enough to give good comfort that they know what they’re doing’.         

‘Laura Tainsh has a very solid understanding of renewables as a whole and has led her colleagues very effectively in the work I need DCS to do for us’.

‘They have a great range of knowledgeable people old and young who check all the facts and always have a solution compared with some firms who don’t search for that solution’.            

‘Laura Tainsh stands out as a person who goes a long way to get the result we look for’.

‘Very confident, even forceful in putting their points across’.     

‘Jaqueline Cook provided us with strong advice and moral support’.

Key clients

Peel Energy

Ripple Energy

ABO Wind AG / ABO Wind UK


SUEZ Recycling and Recovery

Dell Wind Farm Limited (a joint venture between ESB and Coriolis Energy)

Shin-Etsu Handotai Europe Ltd

Mackintosh Family


Pogbie Farms

Work highlights

  • Continue to provide Peel Energy integral and strategic advice in relation to all Scottish on-shore wind projects.
  • Advised Suez Recycling and Recovery UK on restructuring of business and leasing arrangements in relation to energy recovery and landfill gas.
  • Advised Shin Etsu Handotai Europe on the property, construction and environmental aspects of the installation of a new CHP (combined heat and power) plant on the site of the client’s industrial property.

MacRoberts LLP

MacRoberts LLP is renowned for its expertise across real estate, construction, planning, IP, power purchase agreements and energy regulation. The team is experienced in assisting developers, infrastructure providers and public bodies with onshore wind, offshore wind, floating wind, tidal, hydro, solar, heat pumps and biomass generation projects. Nick Jones leads the team and is noted for his onshore windfarm expertise. In 2019, John Macleod joined as partner as a result of the firm's acquisition of Murray Snell.

Practice head(s):

Nick Jones


‘The team have advised us on a variety of matters including complex acquisition projects, commercial contracts, and employment law’.

‘We were given access to MacRoberts’ bid support team who helped us win a key contract, which has been transformational to our business’.

‘Being given not only legal support, but also business support, really sets MacRoberts apart from other lawyers with whom we have worked with in the past’.           

‘David McGuire, who has an abundance of sector knowledge’.

‘The biggest compliment I can pay MacRoberts is that they develop expertise with us’.

‘They balance the commercial and legal with ease’.

‘Proactive and helpful support and ideas, not just answering client questions, but adding value as part of the team’.  

‘Nick Jones is friendly and reliable’.

Key clients

SP Energy Networks (including both transmission and distribution companies)

Together Energy Limited

Falck Renewables Wind

Brookfield Renewable UK

Coriolis Energy

GridCodePower Ltd


ENGIE Renewables

Breedon Group/Breedon Northern

Tillicoultry Quarries

Work highlights

  • Continuing to act for the developer in the site assembly of numerous land, access and cabling agreements for leases and servitudes for the Chirmorie Wind Farm Project.
  • Advised Smarter Grid Solutions in connection with complex sub-contracting arrangements with two sub-contractors, Greensync and with Nexant, Inc. to enable the client to perform its agreement with UK Power Networks (Operations) Limited.
  • Acted for Together Energy Limited on the employment law aspects of the investment of £18m by local authority, Warrington Borough Council.

Morton Fraser

Morton Fraser is noted for its expertise in crofting and agricultural-related energy matters. It acts for landowners and developers on consenting, licensing, developing, financing, decommissioning, remediation, re-powering and commercial agreements. Practice head Nick Atkins is an expert in nuclear and environmental law.

Practice head(s):

Nick Atkins

Other key lawyers:

Linsey Barclay-Smith


‘Outstanding quality of communication and excellence of knowledge.’

‘Patient, responsive, and excellent communication.’


Key clients

United Kingdom Atomic Energy Authority, Dounreay Site Restoration Limited

Ministry of Defence

Orkney Council

Glenmuckloch Community Energy Park Limited

Scottish Wildlife Trust

Aultguish Wind Farm

Inverliver Hydro Scheme

BTO Solicitors LLP

The Scottish Ministers

Work highlights

  • Advising Orkney Council on the development of renewable energy projects by the council on their own property and that of third parties.
  • Advising BTO on the specialist crofting law aspects of a hydro-scheme purchase by their clients.
  • Continuing to act for the Scottish Ministers in connection with all renewable energy projects on their considerable land ownership across Scotland, in particular, the crofting estates in the west and north of Scotland.

Ledingham Chalmers LLP

Ledingham Chalmers LLP's team has particular experience of onshore wind farms, where it generally acts for landowners. It also acts for landowners and developers on hydro schemes. Peter Murray and Jim Drysdale are the joint heads of the practice.

Practice head(s):

Peter Murray; Jim Drysdale

Key clients

Arjowiggins Group  Limited

Aberdeen Renewable Energy Group

Puffin Energy Limited

Pale Blue Dot Energy Limited


Work highlights

  • Provided general corporate and contracting advice and assistance in relation to Aberdeen Renewable Energy Group.
  • Providing general counsel and strategy advice to Pale Blue Dot Energy Limited.
  • Providing general corporate and contracting advice and assistance to ClearCost Energy (GB) Limited.


TLT is known for its expertise in clean energy M&A and project finance. Onshore wind is a particular area of expertise, and the firm has also been involved in large solar projects. Nick Shenken now leads the team following Richard Turnbull’s departure to Shepherd and Wedderburn. Caroline Ramsay joined as a partner from Pinsent Masons LLP.

Practice head(s):

Nick Shenken

Other key lawyers:

Caroline Ramsay


‘The team are extremely focused on understanding and delivering on the clients needs and are extremely responsive.’

‘Extremely personable and go the extra mile to be responsive and an engaged member of the team.’

Key clients

Blackfinch Investments

Aurium Capital Markets

Blue Wind Energy

Triodos Bank UK Ltd

Abundance Investments

REG Power Management Limited

The Renewables Infrastructure Group

Offshore Renewable Energy Catapult


Dounreay Site Restoration Limited

E2 Energy plc

Intelligent Land Investments Group plc

ILI Energy Storage plc

Peterborough City Council

Work highlights

  • Following a competitive tender process TLT was awarded a place on Offshore Renewable Energy Catapult’s (ORE Catapult) four year Legal Services Framework.
  • Advised ILI Energy Storage plc in respect of a fundraising in terms of which they secured an investment of £1.6m from investors in the Abundance Investment Limited syndicate.
  • Advised on all corporate and banking aspects of E2 Energy Plc’s fundraising, which raised c£2.9m investment from investors in the Abundance Investment Limited syndicate to fund the acquisition of further operational wind turbine assets.

Wright, Johnston & Mackenzie LLP

Wright, Johnston & Mackenzie LLP is becoming increasingly prominent in the private wire and ICP connection market. The team, which is led by Andy McFarlane, is also particularly experienced in the onshore wind space. The renewables practice draws upon the firm's strengths in multiple areas, including property, planning, environment, construction and dispute resolution. Clients range from independent developers to major utilities.

Practice head(s):

Andy McFarlane

Other key lawyers:

Fraser Gillies

Key clients

Renewable Energy Systems Limited

Innogy Renewables UK Limited

Muirhall Energy Limited

Vento Ludens Limited

Coriolis Energy Limited

Partnership for Renewables

Fred Olsen/Natural Power

Brookfield Renewables UK Ltd

SIMEC Wind One Limited

BayWa r.e. UK Limited

Work highlights

  • Advising Renewable Energy Systems Limited on  all development work, including the ICP grid connection, at Blary Hill Wind Farm.
  • Advising Brookfield Renewable UK Limited on issues of consent at the Larbrax Wind Farm.
  • Advising Crystal Rig IV Limited, a subsidiary company of Fred. Olsen Renewables Ltd (FORL), with lead consultants Natural Power, in relation to a s.36 scheme.