Are you planning a facility expansion or looking to replace your existing standby power system? Diesel fuel has been the fuel of choice for standby backup power systems, but is it the best choice?
Our diesel guy, Chad Dozier will tell you, "There are many advantages to diesel engines, when used in standby applications." For example:
Start time and load acceptance: Diesel is your best bet to comply with NFPA 110 standards for 10 second power restoration and 100% rated load acceptance in a single load step. This is a requirement for life safety systems in the U.S. Further, the diesel generator set provides better transient response than an equivalent gas generator set.
Local fuel supply: Legally required standby systems require the generator set to operate for extended periods of time without being re-fueled. And often times a facility owner/operator will require that their generator sets can run for extended periods without the need for an external fuel supply. Both scenarios drive the need for on-site fuel storage. With diesel engines, on-site fuel storage is easier to accomplish.
Installed cost: Diesel gensets typically cost 40%-50% less to procure and install than an equivalently sized industrial grade gaseous fuel genset, although commercial grade automotive derivate engines less than 200 kW can be on par with diesels on installed cost.
Power density: Diesel generator sets provide 20%-40% more power per square foot than an equivalent gas generator set, resulting in smaller engine rooms when using multiple generator sets.
However, Gas Man Nick Kelsch will remind you, "Gas generator sets should not be ruled out." Reasons include:
Fuel maintenance: Diesel fuel that is left unmaintained and in storage tanks for extended periods can foster bacterial and microorganism growth that will plug filters and cause fuel system failure. This necessitates installation of fuel polishing equipment or is resolved by using pipeline gaseous fuel.
Run time in a natural disaster: During a hurricane, natural gas continues to flow whereas diesel fuel transportation trucks can not always reach hospitals, pumping stations, and hotels. Major storm events are much less of a threat to a natural gas pipeline than they are to road transit.
Environmental benefits: Lean burn gas gensets generally emit 90% less nitrous oxides than diesel as well as 60% less carbon monoxide (with oxidation catalyst). Visible soot emissions are nearly eliminated.
Non-emergency flexibility: Operating a genset during peak electrical demand in parallel with or isolated from a local electric utility is one way that genset owners can turn an emergency use asset into one that creates economic benefits. Given the strict use limitations related to diesel emission regulations today, gas gensets offer a good alternative. Further, as natural gas prices have declined dramatically in the US in recent years, gas gensets are more economical to own and operate at 500+ hours per year.
What are your thoughts on this?
Can gas generator sets be a viable option for standby installations?
Do you have experience with standby gas gensets applications?
How does it compare to a diesel in your experience?
What are some other considerations that should be factored into the decision between gas and diesel generator sets?