The waste-to-energy group said Yeo has resigned with immediate effect for personal reasons but will remain as a consultant to Powerhouse for a period of 12 months.
Greenstreet has been a non-executive director of Powerhouse since 2011 and is a founder of aircraft lessor, Falko Regional Aircraft.
He also sits on the board of regional airline CityJet DAC and Electric Aviation Group.
Yeo will receive a settlement of GBP35,000 for the termination of his contract as executive chairman while the consultancy agreement provides for a monthly fee of GBP6,000 per month.
“It has been an honour to lead Powerhouse through an important phase of its development. Under my chairmanship Powerhouse’s management and finances have been substantially strengthened and the SPV which is building our first commercial-scale plant has been placed on a firm footing,” Yeo said.
“The arrival of our new CEO will ensure this progress continues. Now is therefore the right time for a younger chairman to take over the reins.”
James Greenstreet added: “On behalf of the whole board and our shareholders I thank Tim warmly for his tireless work for Powerhouse over the last fourteen months.”