Project-based transactions (PBTs) are a market mechanism of attracting foreign investments in order to abate greenhouse gas emissions and increase energy efficiency of the countrys enterprises. The article provides a classification and analyzes advantages and drawbacks of PBTs from the point of view of a host country. The main trends and factors determining the dynamics of the PBT market are described. Given that Russia currently lags behind the leaders of the PBT market, an incorporation of a state carbon fund is put forward with an aim of channelling PBTs through it. This paper proposes a form of PBT market regulation by incorporating an option mechanism into the contract structure of a transaction. A comparison of the new form of regulation with the tools that are currently in use in Russia and other countries demonstrates its greater economic efficiency under uncertainty.