NOAA/RAMMB Satellite Image of Florence
Torrential rain pummeled the Carolinas once Hurricane Florence made landfall. The slow-moving storm inched along, leading to widespread emergencies. Parts of several rivers were in “major flood” stage, and flash-flood watches and warnings were in effect in many towns. Floodwaters reached all-time highs, and thousands of water rescues were performed as people were trapped. Florence became deadly, claiming dozens of lives.
North Carolina took the brunt of Florence’s force and nearly one million people were without power. Power outages were a lingering issue as crews faced challenging conditions to restore power to homes and essential services. Airports, gas stations, hotels, grocery stores and many others were without power as they waited for conditions to improve for crews to reach them. Road after road was rendered impassable. Transportation officials said the list of roads that were blocked from the flooding and debris was too long to fathom. Officials begged people to stay off the roads. The city of Wilmington, N.C., was deemed an island as conditions made it impossible to get in and out of the city. People waited in long lines for ice, gas to run generators and other supplies that were flown into the city. A local water utility had even issued a dire warning that it was at one point critically low on diesel fuel. Cape Fear Public Utility Authority urged residents to fill their bathtubs with water in case the utility ran out of fuel to keep their plant running. The county was able to come up with enough fuel, but it underscores what days or weeks without power and outside help can do.
“Power outages are becoming a way of life,” said Aaron Jagdfeld, president and CEO, Generac Power Systems. “We all have seen some of the amazing destruction and disruption major storms cause. Clearly the frequency and the duration of these events, the scale of these events, appears to be getting larger so having a backup plan whether you are a homeowner or a business owner is important.”
Jagdfeld said natural gas is becoming a popular fuel of choice for backup power. He said the natural gas infrastructure seems to stay intact in these types of events because it is underground and it is not disrupted by water.
A spokesperson for Piedmont Natural Gas, the utility provider in the hardest hit areas, said the storm had caused few, if any problems. Storm threats to gas service range from residential lines uprooted by fallen trees to submerged gas-driven appliances in flooded areas.
There were several issues for generator owners requiring diesel fuel. Evacuations along the East Coast and “panic buying” among consumers worried about running out of fuel for cars and generators contributed to shortages in parts of North Carolina, South Carolina and Virginia. Flooding and debris also made it challenging to get more fuel after the storm made landfall.
“With a diesel generator, you will need to get a diesel fuel truck to that generator to refuel it at some point,” said Jagdfeld. “Oftentimes when you have major events like Florence, the roadways are blocked, you have debris and you have an inability to get trucking and logistics working properly. Re-fueling a generator then becomes a large challenge if you are using a diesel set. So natural gas sets are quite a bit more stable, and it is a more robust fuel source in a major event.”
Generators require sufficient fuel supplies for extended running, and long-term outages often expose fuel quality issues when the addition of fresh diesel fuel stirs the fuel contaminants on the bottom of the tank. On-site diesel storage tanks are typically sized to provide 12 to 72 hours of run time. According to NFPA 110, fuel tanks that are subject to temperature variations can experience accelerated fuel degradation, especially if the tanks are outside and above ground. The presence of water can lead to microbiological contamination and growth, which in turn can lead to general or pitting corrosion of steel tanks and components, possibly resulting in filter plugging, operational issues or a hydrocarbon release into the environment.
In a report recently published by The Gas Technology Institute (GTI), all electric customers typically have one outage per year, while on average only one in 112 gas customers is expected to experience an outage in any given year. GTI’s data said most natural gas outages are for planned equipment replacement. Meanwhile, the data also states that for unplanned outages, only about one in 800 natural gas customers are affected per year. This data, and as seen by the events of Florence, show underground natural gas pipelines are not especially vulnerable to weather conditions and have proven stable and dependable throughout many major emergency events. The resilience of the natural gas infrastructure allows for cost-effective, clean, reliable power generation. Customers can also benefit from not having to replenish onsite liquid fuel tanks when backup is needed to provide extended power. In extreme weather events, GTI said delivery of over-the-road fuel supplies can be disrupted for days to weeks.
While electrical distribution service reliability is high, for some end users the impact of electrical outages at their homes or businesses can be highly disruptive and pose economic hardship. Historically, many standby and emergency generators have been diesel-fueled, especially for commercial and industrial facilities, while gaseous generator units have been used at homes and light-commercial businesses. The traditional practices and historical codes stem in part from the view that onsite fuel storage was either preferable or required.
Reliability of fuel supply is of great concern for code officials and authorities having jurisdiction (AHJs), such as fire marshals or others involved in permitting emergency generators. AHJs do have the flexibility to permit the use of alternative fuels in other standby power applications where there is low probability of simultaneous failure of both the off-site fuel delivery system and the power from the outside electrical utility company. As the natural gas distribution service data highlighted in GTI’s report, the probability of a customer losing natural gas service during an unplanned event is quite low, and customers continue to remain largely unaffected in major weather events, as well.