Senior Plant Engineer
Job Title: Senior Plant Engineer
Department: Engineering / Operations
Reports to: President / Plant Manager
Location: Keyes, CA (In-office)
Position Overview:
Aemetis Advanced Fuels Keyes, Inc. (AAFK) owns and operates a 65-million-gallon-per-year corn-to-ethanol production plant in Keyes, California — the largest low-carbon ethanol facility in the state. The plant operates continuously, 365 days per year, and is currently executing a $35 million Mechanical Vapor Recompression (MVR) upgrade that will reduce natural gas consumption by approximately 80% and add an estimated $32 million per year in operating cash flow. AAFK is a subsidiary of Aemetis, Inc. (NASDAQ: AMTX), headquartered in Cupertino, California.
AAFK is seeking a high-caliber Senior Plant Engineer to serve as the sole senior engineer on-site. This individual will be the plant’s technical authority for all process, chemical, and mechanical engineering matters. The role carries direct accountability for process optimization, carbon intensity reduction, energy efficiency improvements, and capital project execution. With a clear path to Director of Engineering for the right candidate, this is a foundational leadership hire for a plant in active transformation.
The Senior Plant Engineer reports directly to the President of AAFK with a dotted-line relationship to the Plant Manager, and collaborates closely with operations, finance, and the corporate compliance team. The right candidate translates deep ethanol process expertise into measurable gains in yield, increased energy efficiency, and carbon intensity reduction.
Key Responsibilities:
· Process Engineering & Optimization
o Serve as the process engineering authority for all ethanol production unit operations, including liquefaction, fermentation, distillation, dehydration, evaporation, molecular sieve systems, and mechanical vapor recompression.
o Develop and maintain mass and energy balances, thermodynamic models, and hydraulic analyses to characterize and continuously optimize plant performance.
o Lead root cause analysis and corrective action for process upsets, yield losses, and efficiency gaps; translate findings into revised operating procedures and engineering controls.
o Apply chemical and process engineering principles to identify and implement yield improvement, energy reduction, and carbon intensity reduction opportunities.
o Evaluate fermentation performance, yeast kinetics, enzyme activity, and mash chemistry; recommend and implement process adjustments in coordination with plant manager and operations.
o Generate and maintain process engineering documentation, including PFDs, P&IDs, process calculations, and equipment data sheets.
o Develop and/or refine 3D equipment layouts, 3D pipe routing models, and isometric fabrication drawings; coordinate with or directly support modelers to produce construction-ready fabrication detail packages.
· Capital Projects & Engineering Deliverables:
o Lead scope development and produce basis of design documentation supporting CAPEX estimation, OPEX projections, vendor selection, and equipment procurement.
o Function as owner’s engineer on larger EPC-delivered projects; review and challenge contractor deliverables including design specifications, engineering drawings, pricing, and vendor packages.
o Execute smaller capital improvement projects in-house, including preparation of P&IDs, equipment lists, piping and material specifications, and construction-ready drawing packages.
o Oversee construction drawing review for permit and construction execution; coordinate with contractors and engineering firms to ensure design intent is achieved in the field.
o Specify equipment, piping, valves, and materials of construction per applicable ASME, OSHA, and relevant building codes.
o Support Process Safety Management (PSM), Process Hazard Analysis (PHA), and EHS activities related to hazardous process systems and flammable fluid handling.
· Carbon Intensity & Regulatory Technical Support :
o Develop and maintain engineering models supporting carbon intensity (CI) pathway analysis and optimization for LCFS, RFS, and Section 45Z production tax credit programs.
o Collaborate with the compliance team to identify capital and operational improvements that reduce CI and increase the value of environmental attributes generated.
o Provide technical data, calculations, and documentation to support regulatory submissions, PSM, third-party audits, and permit applications.
o Support development of engineering-informed P&L models that incorporate energy management, feedstock efficiency, and credit program economics.
· Operations Interface & Continuous Improvement
o Partner with the Plant Manager and operations team to identify improvement opportunities, resolve day-to-day technical challenges, and implement engineering best practices.
o Partner with Plant maintenance and utilities teams to identify and implement preventative maintenance, corrective action, and repairs.
o Develop and present data-driven process analyses and action plans; review, create, and maintain associated technical documentation and standard operating procedures.
o Lead or support commissioning and startup activities for new equipment, upgrades, and capital projects.
o Develop engineering and operational training materials for plant personnel as needed.
Education/Experience :
· Education :
o Bachelor’s degree in Chemical Engineering required; degree in Process Engineering, Biochemical Engineering, or a closely related discipline will be considered. Advanced degree (M.S. or Ph.D.) in Chemical Engineering is a plus. Additional coursework or certification in business, project management, or renewable energy is a bonus.
· Experience :
o 7+ years of process or chemical engineering experience in ethanol production, biofuels, biorefining, or a closely related continuous process industry, with demonstrated hands-on knowledge of core unit operations — fermentation, distillation, dehydration, evaporation, heat integration, and water treatment; corn-to-ethanol or grain-based fermentation experience preferred.
o Experience with energy efficiency and related systems, including heat exchanger systems, vapor recompression, or utilities optimization, is highly valued.
o Experience functioning as owner's engineer on EPC or design-build capital projects; ability to review, challenge, and approve contractor deliverables.
o Familiarity with PSM, PHA, and OSHA requirements for hazardous process systems.
o Familiarity with LCFS, RFS, or Section 45Z programs from an engineering or CI-reduction standpoint is preferred but not required.
o Registered Professional Engineer (PE) or ability to obtain licensure within 12 months is strongly preferred.
· Skills & Attributes :
o Proficiency in process simulation and thermodynamic modeling tools (Aspen Plus, ProMax, Pipe-Flo, or equivalent).
o Working knowledge of AutoCAD and Bluebeam; experience with Navisworks or 3D plant design software a plus.
o Ability to develop and defend engineering economic analyses and carbon intensity pathway calculations; strong quantitative skills overall.
o Ability to communicate complex technical findings clearly to non-engineering audiences, including senior leadership, compliance teams, and regulatory stakeholders.
o Entrepreneurial mindset suited to operating as the sole on-site engineer; comfortable setting priorities and managing multiple concurrent initiatives independently.
o Collaborative, low-ego leadership style aligned with a small, high-performance operations team.
Working Conditions: This is a full-time, on-site position located at the Aemetis Advanced Fuels Keyes facility in Keyes, California. The role requires regular presence on the plant floor and in the control room, and strong partnership with Plant Manager on setting priorities and implementing changes. Periodic travel to Cupertino corporate offices, regulatory meetings, and vendor or contractor sites may be required.