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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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Plastics and pack­aging laws in Bul­garia
1. What is the gen­er­al le­gis­lat­ive frame­work reg­u­lat­ing pack­aging and plastic waste in your jur­is­dic­tion? On a na­tion­al level, the Bul­gari­an Waste Man­age­ment Act (“WMA”) provides the gen­er­al le­gis­lat­ive...
Cent­ral and East­ern Europe
An­oth­er new source of fin­ance is the Three Seas Ini­ti­at­ive In­vest­ment Fund, backed by vari­ous CEE na­tion­al de­vel­op­ment fin­ance in­sti­tu­tions. This made its first in­vest­ments in 2020, buy­ing a con­trolling in­terest in Green­ergy Data Cen­ters, a CEE data centre plat­form, and Cargounit, a key play­er in the CEE rail­way in­dustry. The fund is in­ten­ded to com­ple­ment and strengthen the cap­it­al de­ploy­ment of in­di­vidu­al Three Seas coun­tries and EU fin­an­cial in­stru­ments.Some CEE na­tions have also signed up to China’s Belt and Road Ini­ti­at­ive (BRI), al­though the amount of Chinese in­vest­ment that has oc­curred vari­ous sig­ni­fic­antly between coun­tries, with many re­gion­al BRI pro­jects be­ing in smal­ler non-EU states. Bol­ster­ing con­nectiv­ity There is sig­ni­fic­ant fo­cus on con­nectiv­ity – both phys­ic­al and tech­no­lo­gic­al – across CEE. Re­gion­al policy ob­ject­ives in­clude strength­en­ing EU in­teg­ra­tion by en­han­cing the se­cur­ity of in­fra­struc­ture sup­ply and con­trib­ut­ing to en­hanced in­ter­con­nectiv­ity between EU mem­ber states. The rail sec­tor in par­tic­u­lar has ini­ti­ated prom­in­ent cross-bor­der pro­jects, such as the mod­ern­isa­tion of the Bud­apest-Bel­grade line, and the con­struc­tion of a line between Katowice in Po­land and Os­trava in the Czech Re­pub­lic. Work also con­tin­ues on the Rail Balt­ica net­work, aimed at in­teg­rat­ing the Balt­ic States in­to the EU’s rail net­work.In con­trast, des­pite the re­gion’s good 4G cov­er­age and re­l­at­ively com­pet­it­ive fibre broad­band avail­ab­il­ity, 5G pen­et­ra­tion looks likely to be slow, with many pro­grammes hav­ing been dis­rup­ted by the pan­dem­ic. While the CEE di­git­al eco­nomy has been grow­ing strongly, without ad­di­tion­al in­vest­ment in in­fra­struc­ture its tech­no­lo­gic­al com­pet­it­ive­ness may be at risk – al­though key di­git­al lead­ers, such as Es­to­nia, are likely to re­tain their strong po­s­i­tions. En­ergy trans­form­a­tion gath­ers pace CEE coun­tries are mak­ing great strides in the en­ergy sec­tor. Mar­ket par­ti­cipants ex­pect to see a wave of EU back­ing for en­ergy trans­form­a­tion pro­jects. De­cent­ral­ised en­ergy sys­tems are driv­ing in­vest­ment in net­works, and cli­mate change tar­gets are spur­ring pro­gress in areas such as re­new­able en­ergy, waste-to-en­ergy in­fra­struc­ture and, in some coun­tries, nuc­le­ar new build.
Law and reg­u­la­tion of con­sequen­tial dam­ages clauses in the en­ergy sec­tor...
1. Do the words “con­sequen­tial loss” have a giv­en mean­ing in law? Bul­gari­an law does not re­cog­nise the term “con­sequen­tial loss”.Un­der Art­icle 82 of the Ob­lig­a­tions and Con­tracts Act (OCA)...
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...
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...
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...
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...
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...
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...
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...
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...
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...