Biogas upgrading system in Anklam, Germany
Anaerobic digestion plant in Anklam, Germany.

Established in 1985, Evergreen Engineering®, Inc., is a multi-discipline, full-service consulting engineering firm serving the power generation, wood products, pulp & paper, chemical, and resin industries. With offices in Eugene, Oregon, Atlanta, Georgia, and Everett, Washington, Evergreen serves clients throughout North America and around the world.

Evergreen is on the cutting edge of emerging waste-to-energy technologies. We have designed systems utilizing pyrolysis, gasification, and anaerobic digestion. Because these techniques have the potential to produce more power from the same fuel than is possible with direct combustion, modern renewable initiatives are calling for more such facilities around the country. Put our expertise to work for you as a leader in this growing industry.


Agilyx digesters
Agricultural waste-to-biogas anaerobic digestion plant in Oregon.

Our multi-discipline engineering experience with biomass raw materials is broad and encompasses resource assessments through complete design and construction of biomass handling and processing systems for woody biomass materials, wood wastes, agricultural crops and residuals, mixtures of wood and paper mill wastes and mixtures of wood and coal. We have successfully completed hundreds of projects at sawmills, plywood plants, pulp and paper mills, and biomass power facilities ranging from feasibility studies to complete greenfield construction of new manufacturing plants, including site development work, environmental permitting, and interfacing with electrical utilities.

Our team approach to projects incorporates all applicable engineering disciplines with considerable practical experience, resulting in projects that are efficient, cost-effective, and exceed the expectation of our clients. Each Evergreen project is led by a dedicated Project Manager (PM) who is involved in all facets of the process and is the single point of contact for the effort, except where issue-specific arrangements have been agreed upon. A Principal in Charge (PIC) is assigned to each project to ensure that our clients are satisfied with the quality and responsiveness of the Evergreen Team and ensuring that each client has direct access to the ownership of Evergreen.

Evergreen provides a complete engineering solution for your biogas plant including process design, layout, site work, structural, electrical/controls, mechanical, piping, permitting, and project management.

Examples of Evergreen’s RNG projects