Management team

Greg Cook

Greg Cook

President and CEO

Greg Cook brings more than 30 years of experience into the energy industry. He joined Greeleaf Power in November 2019 as Chief Operating Officer.

Prior to joining Greenleaf Power, Greg served as the Project Director for Plum Point Generating Station. Greg was the V.P. of Operations for Perennial Power, in that capacity he was responsible for overseeing the operation of multiple combined cycle plants totaling over 800 mw.

He was also the General Manager for the 475 mw Hermiston Generating plant in Oregon for 10 years. He has experience in Combined Cycle, Pulverized Coal, Circulating Fluidized bed, Waste to Energy, Reciprocating engines (Mass Burn) and Biomass technology.

Greg started his career in the United States Air Force, boiler operations, serving in Germany for 3 years. Following his tour in the Air Force he continued his career in California on three different biomass plants.

Matthew Brown

Matthew Brown

Chief Financial Officer

Matt Brown is responsible for the direction and administration of the organizations accounting, finance and administrative operations. In addition to focusing on operating an effective finance operation, ensuring control of the Company’s assets and records, and minimizing risk, Matt is integral in shaping the overall strategy and direction of the Company and being a catalyst for instilling a financial approach and mind set throughout the company to help other parts of the business perform better.

Prior to joining Greenleaf Power, Matt worked for TechnipFMC and Cox Automotive in various finance and accounting roles focusing on growing top and bottom-line performance through execution, efficient operations, increasing market share, acquisitions, and product development. Matt also worked for several years in public accounting.

Matt holds a Masters of Accountancy from Golden Gate University, BS in Business Administration from San Diego State University and has been an active Certified Public Accountant since 2005.


Erin Hazen

Vice President, Development

A renewable energy professional with 14 years of experience in the wind, solar, biomass, and energy storage sectors, Erin Hazen has expertise in the acquisition, development, interconnection, and construction of complex utility-scale renewable energy projects. With a career development pipeline totaling over one gigawatt in ERCOT, MISO, SPP, CAISO, NYISO, PJM, WAPA and in the southeast, Erin has expertise in energy project permitting, real estate acquisition, project due diligence and M&A, generation technologies, renewable and biomass energy policy and economics, power marketing, community outreach, GIS mapping, and the management of complex technical projects.

Prior to joining Greenleaf Power, Erin directed a development portfolio of standalone battery energy storage and storage + Solar PV projects for GlidePath Power Solutions, and wind energy development for Acciona Energy. She also spearheaded the Zero Coal initiative at University of Iowa, leading the transition of its coal-fired boilers to biomass energy by developing new fuel supply chains which included cultivated energy crops and biomass-based engineered fuels.

Erin holds a Bachelor of Arts degree from Gettysburg College in Pennsylvania.


Geoff Harmon


Responsible for treasury and FP&A functions at Greenleaf Power.

Since joining Greenleaf in 2012, Geoff has been integrally involved in contract negotiations and administration, including multiple financing and PPA negotiations.

Prior to joining Greenleaf Power, Geoff spent seven years with Granite Construction supporting real estate investment and development projects. Geoff also has experience as a consultant doing real estate analysis on SCE's interconnection cost analysis team, as well as time in public accounting and public finance consulting. Geoff holds a BA in Economics and a Master of Professional Accountancy from Indiana University, Bloomington.

Mitchell Martin

Mitchell Martin

P.E., Operations and Engineering Director

Mitchell Martin joined Greenleaf in November 2011, serving as Project Engineer prior to his current role. Mitchell is responsible for the day-to-day operations of the plants, as well as engineering, capital planning, budgeting, and oversees EH&S and IT functions. Additionally, Mitchell has been an integral part of Greenleaf’s acquisition and due diligence team, and helps interface between operations and accounting.

Prior to joining Greenleaf, Mitchell worked in the oil and gas industry as a design engineer for offshore platforms.

Mitchell holds a BS in Mechanical Engineering from Texas A&M University and is a Professional Engineer in the state of California.


Kendra Sage

Human Resources director

Kendra Sage joined Greenleaf Power in 2016. She serves as Human Resources Director bringing over 20 years of Human Resources experience to the team. Prior to Greenleaf Power, Kendra managed the Human Resources function in various small to mid-sized companies. Kendra holds a Bachelor of Science degree in Human Resources from California State University, Fresno.