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Portrait of Kostadin Sirleshtov

Kostadin Sirleshtov

Managing Partner
CEE Head of Energy & Climate Change

CMS Sofia
Landmark Centre
14 Tzar Osvoboditel Blvd
1000 Sofia
Languages Bulgarian, English

Kostadin Sirleshtov is Managing Partner at CMS Sofia and Head of Energy & Climate Change for CEE.

His particular area of expertise is in conventional, nuclear, renewables, oil & gas, infrastructure, projects, PPP, public procurement, underground resources. He has worked as the Chief of the Minister’s cabinet for the Ministry of Energy and Energy Resources. 

Kostadin has vast experience in the conventional power and electricity sector. He has represented clients, including renewables organisations, in negotiations with the Bulgarian Government, National Electricity Company and the Electricity Transmission System Operator. He has also advised major international oil & gas prospecting and exploration companies in Bulgaria on various onshore and offshore projects. In addition, he is particularly focused on advising renewables companies (in relation to wind, hydro, solar and biomass projects) on the development, operation and/or sale of their projects in Bulgaria, including on litigation matters.

Kostadin is ranked as one of the top Bulgarian energy experts in the world's leading legal directories Chambers & Partners and Legal 500.

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"Top-rated energy partner Kostadin Sirleshtov leads the team, and is praised by interviewees as a "distinguished, pleasant and upbeat" lawyer with "huge knowledge and understanding of the sector." "


Relevant experience

  • A consortium of major international oil & gas companies on the largest oil & gas exploration project in Bulgarian history – offshore Black Sea “Han Asparuh” block. The work included authorisations grant assistance, environmental regulations and other regulatory assistance, assistance in the preparation and conduct of the calls for tender for the procurement of the operational contracts, public procurement assistance, representation before governmental authorities etc.
  • Petroceltic (formerly Melrose Resources) on their oil & gas exploration activities in Bulgaria, including recently on the successful negotiations and signing of an extension of the exploration of oil & gas in the Black Sea’s Galata block, negotiations and signing of new production concession agreements, on-going work related to the intended project for the conversion of a depleted field into a gas storage facility. Petroceltic is Bulgaria’s biggest British investor and since 2001 has discovered four deposits of natural gas and produced natural gas in excess of 3 billion m3.
  • Toshiba International Europe Limited on the successful completion of their EUR 50m project for rehabilitation on Units 5 and 7 of the largest Thermal power plant in Bulgaria Maritsa East 2. We advised on all legal and strategic aspects of this largest deal in the electricity sector in Bulgaria to date, including on first stage of the project for replacement of the turbine at Unit 2 of TPP Maritsa East 2 estimated at EUR 25m.
  • ENEL (Italy) on the Belene nuclear power plant, undertaking full legal due diligence of the Belene nuclear project. Members of our team were involved in preparing the feasibility studies and advising the project consultant during the implementation stage.
  • Foster & Partners on the project design agreement of the new Passenger terminals for Varna and Burgas Airports. The project involved the preparation of the offer and the respective documents, representation during the negotiation phase and revision of the design contract.
  • SDN Company and Korea Development Bank (Korea) on the legal due diligence and acquisition of 5 solar projects in Bulgaria with installed capacity of 58 MW and the establishment of a local subsidiary. The work included: corporate and regulatory advice; legal due diligence; negotiations; assistance with implementation, the successful financing of three projects worth EUR 180m from Korea Development Bank and Unicredit Bulbank.
  • Iberdrola Renovables SA (Spain) on the acquisition of a 74 MW wind farm project in Northern Bulgaria. The work included full legal due diligence, preparation of the transactional documents, completion of the security package and post-closing assistance. This project, worth over EUR 150m, is among the biggest wind farm acquisition projects in Bulgaria. Upon acquisition, we assisted the client with the licensing of the project with the Bulgarian State Energy and Water Regulatory Commission and in the negotiations with the Bulgarian National Electricity for the signing of the Final grid connection agreement.
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  • Regular publications in the International Comparative Legal Guides to Oil & Gas Regulation, Mining Law, Environmental and Climate Change Law, Public Procurement.
  • Chapter on Energy in Bulgaria in the 3rd edition of Energy Global Legal Insights. 
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Lectures list

  • 5th Regional Energy Conference (October 28-29, 2014, Sofia)
  • Gas Storage and Transmissions (June, 17-18th June 2015, London)
  • The Eurasian Natural Gas Infrastructure Conference (June 9-10, 2015, Istanbul)
  • Energy from Waste Conference (October 2014, London)
  • Shale Gas Environmental Summit (October 2014, London) 
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  • 2000 – LLM, Sofia University St. Kliment Ohridski, Sofia
  • 2000 – EU Law and Contemporary English law, Cambridge University, Cambridge
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Show only
27 January 2021
Bul­garia launches EUR 73 mil­lion gas in­ter­con­nect­or pro­ject
Bul­garia is launch­ing a pub­lic pro­cure­ment for Gas In­ter­con­nec­tion Bul­garia-Ser­bia (IBS), a re­verse con­nec­tion that will link the na­tion­al gas trans­mis­sion net­works of Bul­garia and Ser­bia. The es­tim­ated...
26 January 2021
Bul­garia boosts reg­u­lat­ory sup­port for new re­new­ables
In line with Bul­gari­a's le­gis­lat­ive sup­port of new re­new­able en­ergy pro­jects, law­makers in Sofia ad­op­ted a series of amend­ments to the Bul­gari­an En­ergy Act, which boosts sup­port for new re­new­able en­ergy...
25 January 2021
Bul­garia ex­pects bids for Sofia EfW plant by 15 March
After ten years of pre­par­a­tion and stud­ies, the Sofia dis­trict heat­ing util­ity an­nounced a tender for the Sofia EfW plant to be op­er­ated by re­fuse-de­rived fuel (RDF), with the dead­line for sub­mit­ting...
19 January 2021
Ad­vising the Board on En­vir­on­ment­al Law Risk in CEE
Dir­ect­ors’ risk re­port En­vir­on­ment­al law is firmly and un­doubtedly a board-level is­sue and all busi­nesses need to fo­cus on how it im­pacts their activ­it­ies. En­vir­on­ment­al au­thor­it­ies ex­pect dir­ect­ors...
06 January 2021
Bul­garia bets on off­shore wind as post-2030 power source
In line with the EU strategy on off­shore re­new­able en­ergy, Bul­garia is plan­ning a five­fold in­crease in its in­stalled ca­pa­city from wind re­sources between 2030 and 2050, ac­cord­ing to the draft "Sus­tain­able...
04 January 2021
Bul­garia con­tin­ues sup­port of oil and gas ex­plor­a­tion
De­clar­ing po­ten­tial dis­cov­er­ies as "one of the main factors for the en­ergy se­cur­ity of the coun­try", the Bul­gari­an gov­ern­ment has pledged re­newed sup­port for oil and gas ex­plor­a­tion through its draft...
18 December 2020
Re­new­able en­ergy law and reg­u­la­tion in Bul­garia
1. Brief over­view of the re­new­ables sec­tor In 2002, Bul­garia rat­i­fied the Kyoto Pro­tocol to the United Na­tions Frame­work Con­ven­tion on Cli­mate Change, which im­posed cer­tain tar­gets on Bul­garia to re­duce...
19 November 2020
CEE busi­nesses keen on ‘green’ Belt & Road Ini­ti­at­ive op­por­tun­it­ies, CMS...
CEE busi­nesses are in­creas­ingly in­ter­ested in en­vir­on­ment­ally-friendly and sus­tain­able sec­tors as areas for fu­ture Belt & Road Ini­ti­at­ive (BRI) in­vest­ments, while tra­di­tion­al trade-re­lated sec­tors such...
19 November 2020
The elec­tri­city mar­ket in Bul­garia - small re­new­ables to enter the free...
As part of the on­go­ing re­form of the Bul­gari­an en­ergy sec­tor, on 11 Novem­ber the par­lia­ment’s En­ergy Com­mis­sion filed a new Bill for amend­ment and sup­ple­ment of the En­ergy Act, which con­tin­ues the policy...
16 November 2020
Gas Traders Li­cens­ing on the Start in Bul­garia
Midst this year, the Bul­gari­an law­makers de­cided on new re­quire­ments for gas traders to be present on the mar­ket.  Start­ing 1 Oc­to­ber 2021, gas traders must be li­censed to trade in Bul­garia.  In or­der...
04 November 2020
Bul­garia in­tro­duces bill sup­ple­ment­ing pub­lic pro­cure­ment le­gis­la­tion
Bul­gari­an law­makers have ap­proved at first hear­ing a Bill for Amend­ment and Sup­ple­ment of the Bul­gari­an Pub­lic Pro­cure­ment Act, which cov­ers op­tions for amend­ments with­in a con­cluded pub­lic pro­cure­ment...
14 September 2020
Bul­garia to triple photo­vol­ta­ic ca­pa­city by 2030
In ac­cord­ance with the Bul­gari­an En­ergy Act, the Bul­gari­an Min­istry of En­ergy has draf­ted the 'Sus­tain­able En­ergy De­vel­op­ment Strategy to 2030'. This draft Sus­tain­able En­ergy De­vel­op­ment Strategy for...