About Us


 Based in Boulder, CO, EPSIM Corporation is a consulting practice serving the public electric utility sector, large energy loads and industrial gas processes. The combined expertise and experience in specialty engineering and utility management fosters the incubation of ideas that transcend traditional silos of consulting. As a result, EPSIM is uniquely positioned to develop, implement and manage innovative client solutions aggressively and efficiently.  


Q: Tell us about EPSIM  

A: EPSIM is a small business with less than ten employees. This allows us to control our overheads, respond faster and more accurately to our clients’ needs, and keep our senior staff engaged in all projects. EPSIM Corporation is fully insured to meet private and government client requirements. EPSIM has a CAGE Code, available upon request.      

Q: Does EPSIM have Standard Terms and Conditions?  

A: Yes. The use of our Terms and Conditions allows us to control our insurance costs while protecting all parties’ liabilities. Occasionally we are asked to use a client’s contract form, in which case we must pass through any incremental cost from insurances.      

Q: How does EPSIM invoice?  

A: Typically on Time & Expense basis, NET-30, based on our standard rates. Our monthly progress invoices fully document each activity billed to the nearest 15 minutes.  Expenses are billed at cost, contingent upon our client’s prior approval. We track and report progress and remaining budget monthly if required by our clients. Overseas projects are invoiced and paid in US Dollars.      

Q: Can I trust EPSIM on a confidential idea or proprietary process?  

A: Yes! Every client project is confidential. We are utterly paranoiac about information security and our network is protected with state-of-the art firewall hardware. Our computers protection software are updated daily. Our office is under video surveillance. We do not use cloud storage, unless asked by a client on a project basis. On the legal side, we will gladly consider signing a Non-Disclosure/Secrecy Agreement before starting on your project.      

Q: Consulting services are costly. Do we really need EPSIM?  

A: Absolutely.  Except for some cases of damage control, the services of an independent expert are an investment, not a cost. Clearly, to build a relationship of trust, our services cannot result in a net cost to our clients. More often than not, our services have resulted in 10:1 or higher benefit return to our clients. We work closely with our clients to meet or stay below their budgets.   

Nils Tellier, PE


   Nils Tellier, PE, founded EPSIM in 2012 to serve the gas process,  cryogenic industries and wholesale electric market customers. He has nearly thirty years of experience with cryogenic processes - including his NTCI Inc. practice founded in 1996 - and over fifteen years with electric utility operations. 

Mr. Tellier is a Professional Engineer licensed in Arizona and Colorado.  He is a retired officer from the French Navy (Groupement Fusiliers Marins).  He is fluent in French and Spanish.