Diesel: The Lifeblood of the Recovery Effort
Additional diesel is delivered by drop trailers and iso tanks; however, these vehicles need to be able to reach the delivery site. In the cases of extreme flooding, even when having a preferred contract, the issue of getting the fuel to the data center can be an issue. That’s a particular challenge in Lower Manhattan, where tunnel access is limited and some roadways remain flooded or are blocked by stranded vehicles.
Hidden Threat: Fuel Contamination
While the supply of fuel is the most critical consideration, another unforeseen problem is fuel contamination. Diesel reserves often sit for long periods of time, which is the opposite of the optimal scenario, in which diesel fuel is used within two to three weeks of leaving the refinery. Because of this, oil companies are not compelled to produce a diesel fuel meant for long-term storage.
Due to tighter regulation and economic concerns, fuel is becoming more unstable and contaminable, industry sources say. Should a disaster strike, there is a chance that diesel reserves are old, leading to premature shutdown of generators. For this reason, data center providers should test fuel samples on an annual basis, and refresh their reserves to prevent this. There are also treatments, such as adding biocides to control microbial growth, chemical additives, and filtering to remove water and sediment that builds up over time.
The NFPA 110 refers to diesel fuel “storage life” of 1.5 to 2 years. “Tanks should be sized so that the fuel is consumed within the storage life, or provision should be made to replace stale fuel with fresh fuel,” the standard recommends. The current refining process means that an even more conservative standard might be needed.
An additional precaution is testing the generators on a regular basis to see if they can handle the load at partial and/or full capacity. The generator itself needs to be brought to full load on a regular basis to prevent damage to it. While testing is integral, there have been issues in the past stemming from failed testing.
So data center providers need complex backup power systems including massive diesel generators, intelligent diesel fuel management and reserves on site, and priority service contracts. Even then, some problems can’t be avoided – especially if your generators are in the basement in a flood zone.
Great article! We all at Patriot Clean Fuel could not agree more!
CarlPosted November 1st, 2012
Propane does not go bad.
Hey Carl, it’s my understanding that Propane should only be used for smaller generators. Diesel generators have the lowest installed cost per kW, take a lot of abuse, and serviceability and local support is usually very good. Start time for diesel is faster as well, which can matter because it needs to kick in in a short window very often. Propane has less power than diesel for comparable physical size and have greater failure rate.
DCPosted November 3rd, 2012
Seven back up generators did not fail at Langone. The system failed. They failed to do something. What? If the hospital is reopening on Monday, then the problem has to have been identified and repaired or they couldn’t legally open.
Propane burns hotter than nat gas or diesel. Therefore the engines typically get derated for use with LP. SO, you buy more and get less. That goes for spark ignited gensets. The converted diesel engines above 150kW offer greater capability for power output, but again deration is more severe with LP and then you run into the issue of EPA emission compliance. Lastly, while propane doesn’t go bad, it’s by far the most difficult fuel to properly plumb to larger units for adequate supply and demand.
Bi-fuel gens that start on diesel and transition to gaseous are another option. They still meet the NFPA 110 requirement for life safety that the engine starts and transfers power in less than 10 seconds. The start on diesel and then transition to a mix of 25/75 extending greatly the run time of the diesel fuel present. Of course, if natural gas is being used, then the supply also must remain constant. And, if LP is used, the on site fuel storage must be refilled.
Sadly, the best solution is diesel and a minimum 72 hour fuel supply at 100% load.
George BPosted November 4th, 2012
The propane vs. Diesel choice has lots of factors, and each factor has factors. Certainly, large generators tend to be Diesel. But Diesels are a PITA; as the article said, you have to coddle and rotate the fuel. With propane, you burn the vapor, so whatever might be in the liquid is a non-issue. And it stores forever, never spoiling or growing bugs.
But the #1 issue is always: what does the Fire Marshal/EPA/Building Dept. say?
I do think *lots* of backup system users will see the light re: not the genset must be dry, but also the tankage and transfer pumps to refill the day tank.