Senior Mechanical Engineer

Lydian is developing the lowest cost sustainable fuels from waste CO2, water, and renewable electricity to decarbonize the aviation industry. Our breakthrough technology replaces oil and gas refining with fully electrified, modular, and flexible reactor systems that produce fuel with 95% lower emissions than traditional jet fuel.

Since our founding in 2021, Lydian has achieved key milestones in record time, including the production of our first liquid fuel from our pilot system, capable of producing ~10,000 gallons of fuel per year for a fraction of the capital and time of alternative approaches. Lydian is backed by top climate investors including Congruent Ventures, Galvanize Climate Solutions, Union Square Ventures, Voyager Ventures, Grok Ventures, and Overture. We are building a motivated, diverse, and collaborative team that is passionate about addressing the growing climate crisis and is committed to excellence in their work. In particular, we look for tenacious people who are energized by solving the hardest, highest impact problems that come their way.

We are looking for a Senior Mechanical Engineer to own the design and development of a proprietary chemical reactor. This includes the design, build, and validation of a first-of-its-kind pilot-scale reactor and then the scale-up to a full-scale reactor system on the critical path to Lydian’s commercial demonstration plant. You will be faced with clean sheet design problems and will need to rapidly iterate through build and test cycles. This role requires balancing strong engineering fundamentals and high-performing reactor design with low-cost manufacturing methods and scalable processes.

• Take end-to-end ownership of a first-of-its-kind Fischer-Tropsch (FT) reactor. This includes conceptualizing thermochemical architectures, overseeing precision fabrication, and leading rigorous hardware-in-the-loop testing

• Drive the "Value Engineering" process—balancing extreme thermal/pressure performance with high-volume manufacturability to hit aggressive cost targets

• Act as the primary technical point of contact for external manufacturing partners. Identify and vet vendors for specialized processes (e.g., vacuum brazing, high-nickel alloy welding, or catalyst coating)

• Conduct regular DFM (Design for Manufacturing) reviews with partners to simplify complex reactor geometries and reduce lead times for critical-path components

• Oversee the instrumentation of test rigs (thermocouples, pressure transducers, gas chromatography) to ensure the team is capturing high-fidelity data that validates chemical kinetics and heat transfer models

• Document standardized operating procedures (SOPs) and safety protocols. Lead the training of junior engineers and technicians to ensure the safe and efficient operation of high-pressure process equipment

• Foster a culture of "Build-Test-Learn," ensuring that every failure is documented via Root Cause Analysis (RCA) and results in a measurable design improvement

• BS or MS in Mechanical Engineering or a related field with 5+ years of professional experience in a high-stakes hardware design and build environment (e.g., aerospace, automotive, or industrial energy)

• Advanced proficiency in 3D modeling and the creation of detailed 2D production drawings, with a mastery of GD&T (ASME Y14.5) to ensure part interchangeability and manufacturing clarity

• Proven track record of applying DFM and DFA principles to reduce part count, cost, and lead times without compromising performance

• Demonstrated ability to lead Root Cause Analysis (RCA) using formal methodologies (e.g., 5 Whies, Fishbone) and implement robust corrective actions

• Ability to derive engineering solutions from first principles. Comfortability performing "back-of-the-envelope" calculations before moving to high-fidelity simulation

• A "Generalist" mindset with the ability to own the entire product lifecycle from conceptual sketching and FEA/hand-calcs to vendor sourcing, hands-on assembly, and validation testing

• Alignment with our mission, vision, and virtues

• Experience with OnShape in a collaborative, multi-user environment

• Familiarity with ASME B31.3 or Section VIII standards for process piping and pressure vessel design

• Experience designing thermal control systems (TCS), including heat exchangers, insulation strategies, and active cooling loops

• Hands-on proficiency with manual/CNC machining, TIG/MIG welding, and industrial additive manufacturing (3D printing)

• A working knowledge of catalysis, reactor design, or mass/energy balances is a significant advantage for our specific hardware stack

• Challenging, collaborative, and meaningful work and an important voice in company development

• Competitive salary commensurate with experience

• Meaningful equity compensation

• Flexible PTO and expectation that all employees take significant time off to rest, recharge, and enjoy life outside work

• Excellent health insurance with 100% of healthcare, vision, and dental premiums covered

• 401(k) with company match