General Motors permits larger back-up diesels at Michigan facility

The Michigan Department of Environmental Quality (MDEQ) is taking comment until Jan. 15, 2015, on a draft Permit to Install (PTI) that would allow the General Motors Technical Center-Warren to install and operate thirteen emergency diesel-fired engines.

General Motors owns and operates the Warren Tech Center which is located in the City of Warren, a Detroit suburb. The Warren Tech Center conducts research on all aspects of automobile development and production, including design, engineering and manufacturing. The equipment at the Warren Tech Center includes engine dynamometers, paint spray booths, wood working operations, metal machining operations, fuel storage tanks, cold cleaners, lab equipment, and space heaters.

General Motors proposes to install at the center a state-of-the-art, computer server facility, to consolidate and upgrade its corporate information-technology (IT) infrastructure. The proposed thirteen emergency diesel-fired engines will provide the required emergency electricity supply for the IT facility. Nine of the proposed engines are part of a Diesel Rotary Uninterruptible Power supply system (DRUPs) and four of the proposed engines are part of conventional mechanical generator sets.

The purpose of the DRUP generators is to ensure an uninterrupted electricity supply, meaning there is zero lag-time between a power supply outage and provision of electricity by the DRUPs. When electricity is supplied by the grid, the DRUPs system spins a wheel to generate momentum. When the electricity supply is interrupted, energy from the wheel sustains the generator until the diesel engine fires up and assumes powering of the generator.

The purpose of the conventional mechanical generator sets is to provide additional electricity generation, but they are unable to achieve full power quickly enough to provide a zero second lag-time. The lag time for a mechanical diesel fueled generator is approximately ten seconds.

This project was first proposed under a PTI approval in 2012. The Warren Tech Center intended to install the thirteen emergency diesel-fired engines in phases spanning multiple years of construction. Until the completion of the project, any changes would warrant reviewing the entire project again. The project was bid out after initially being permitted, and the Warren Tech Center decided to go with a larger mechanical generator set. As such, all thirteen emergency diesel-fired engines again underwent a 2013 PSD review for the increased size of the mechanical generator sets. A PTI issued in April 2013 covered nine 3,010 kW DRUPs engines and four 2710 kW mechanical engines.

This current application proposes to increase the size of each DRUPs unit from 3,010 kW to 3,490 kW. The change in size increased the potential emissions of each DRUP engine; however, the Warren Tech Center determined that the engines will operate in pairs to provide power to each electrical generator, where EUDRUPS9 is the exception because it does not have a paired engine. The engines will power a generator and the generator will provide electricity to the Warren Tech Center. Pairing the engines provides a level of redundancy that enables back-ups should an engine fail to start. The generators cannot handle a full load from two engines, so the engines will either operate one of the paired engines up to 100 percent load or both of the engines up to 55 percent load.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.