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Definition

pl1404010-400kva_natural_gas_backup_generator_with_led_screen_control_panel.jpgNatural gas generators are internal combustion engines that generate electrical current by means of burning methane (natural gas). Mechanical energy is converted to electrical energy by forcing electrical conductors through a magnetic field. These devices are a part of building mechanical systems that serve to provide backup power during grid power failure, and may also be known as "backup generator" or "emergency generator".[1]


Issues Addressed

Natural gas generators serve to address utility power failure. Building systems require energy for normal operation. Power failure may occur for a variety of reasons including downed tree limbs, power overload, equipment malfunction, or utility maintenance needs. Extreme weather events are a key source cause for each of these types of failures. This point is made especially clear in a finding made by the NYS Department of Public Services in their 2012 Electrical Reliability Performance Report: "of the more than 726 million hours of customer interruptions that have occurred since 1989, over 23% (168 million hours) can be attributed to Hurricane Sandy during October and November 2012."[2]

According to the New York City Panel on Climate Change the city is project to endure extreme weather of growing "intensity, frequency, and duration," meaning that until major protections and alterations to electricity grid service are implemented, power failure must be anticipated to be a continually growing risk. New York's power generating facilities much overcome complex issues in order to combat growing risk to coastal areas. The history and many current operating needs of power plants required locating facilities near water. Fuel is often delivered by ship, and large amounts of water are utilized by a variety of power generation facilities for steam or cooling purposes. Placement of power plants in low-laying, coastal areas was not only intentional, but it is a result of the very core operating needs of the current utility system.[3]
powerfailures.jpg
NY Statewide electricity customer hours of interruption - NYS Dept of Public Services

The risk of power failure may one day be reduced, but for immediate resilient design needs preparing for passive survival, operating buildings independent of grid electricity (island mode), and creating distributed power systems are each important to maintaining comfort, health, and safety. Maintaining consistent operations is especially true for critical facilities such as hospitals, fire houses, police stations, emergency operations centers, media communications infrastructure, and assisted care facilities.

RECENT NYC POWER FAILURES
Date
Major NE Power Outage
Aug 2003
Queens Power Outage
July 2006
Man / Bronx Power Outage
June 2007
City-wide
June 2008
Scattered outages
June/July 2010
Hurricane Irene
Aug 2011
Hurricane Sandy
Oct 2012



Considerations

Emergency backup power may be stored or generated in a variety of ways, including solar photovoltaic (solar pv) panels, backup batteries, or through hydrocarbon-burning generators run on diesel or fuel oil. Natural gas is identified as a resilience measure of particular interested because it produces the least amount of greenhouse gas and air pollution as compared to other hydrocarbon-fueled generator options.[4] Relative to zero-carbon options such as solar pv, it is more affordable, given current availability and costs for each. Natural gas service is relatively consistant and typically available during electrical power failure. The combination of availability, cost, consistancy, reliability, and environmental impact make natural gas a recommended option for building owners who wish to maintain building operations through power failure events.[5]

Installation of natural gas generators require technical preparation and emergency planning on the part of building owners / operators. Technical considerations include:
  • locating the generator above the design flood elevation (if located in a flood zone), and away from areas that may be at risk during emergency situations
  • securely connecting steel piping for natural gas lines
  • properly labeling emergency natural gas supply lines
  • ensuring emergency natural gas supply is not cut when emergency shutoff switches are engaged
  • properly venting exhaust away from any building air supply intakes
  • ensuring gas lines maintain consistent pressure, and that automatic shutoffs are in place to halt operation during spikes or drops in pressure
  • identifying and planning for building systems that should be run by available generator power output
  • including generator operations in emergency planning and running regular maintenance tests to ensure proper operation availability[6] [7]



Applications

Of the many communities ravaged by Hurricane Sandy, the Jersey Shore was home to some of the hardest hit. Power outages were rampant statewide following the storm's initial destruction. One community that was able to maintain a level of service was the borough of Seaside Heights, located on a coastal barrier island.

Three 2 MW diesel generators were initially installed at a cost of $4 million as backup power for critical facilities, including the fire house, police station, and emergency service centers. It was also intended to be run during peak power periods to reduce utility charges for the town. The generators were installed well above the base flood elevation, leaving them well out of harms way of storm surge and flood waters. They provided consistent power for emergency services and rescue operations immediately following the storm. Throughout the period of power failure that followed, service was able to be provided to the entire town.[8]

Although this particular application was implemented using diesel-powered generators, it demonstrates the value that emergency power generators provide for community support and emergency operations. This service would not have been available to citizens without the foresight demonstrated by community leaders to install adequately-sized emergency power equipment in a manner that accounted for natural disaster risks. Generators installed without regard to wind or flood risks may have been rendered useless in emergency situations.


References
  1. ^ Diesel Service and Supply. "How Does a Generator Create Electricity?How Generators Work." How Does A Generator Create Electricity? Article on How Generators Work. Web. 08 Nov. 2013. http://www.dieselserviceandsupply.com/How_Generators_Work.aspx
  2. ^ New York State Department of Public Service "2012 Electric Reliability Performance Report" http://www3.dps.ny.gov/W/PSCWeb.nsf/All/D82A200687D96D3985257687006F39CA?OpenDocument
  3. ^ http://onlinelibrary.wiley.com/doi/10.1111/j.1749-6632.2009.05318.x/full
  4. ^ Stenqvist, James, CPD. "Piping for Natural Gas-Fired Emergency Generators." Plumbing Systems & Design May/June (2003): 28-29. http://t4engr.com/Clients_Only/Engineering/EmerGenChecklist.pdf
  5. ^ Urban Green Council, comp. Building Resiliency Task Force. Rep. New York City: n.p., 2012. http://www.urbangreencouncil.org/servlet/servlet.FileDownload?file=015U0000001Eybd
  6. ^ Stenqvist, James, CPD. "Piping for Natural Gas-Fired Emergency Generators." Plumbing Systems & Design May/June (2003): 28-29. http://t4engr.com/Clients_Only/Engineering/EmerGenChecklist.pdf
  7. ^ FEMA. Design Guide for Improving Critical Facility Safety from Flooding and High Winds. FEMA 543 ed. Risk Management Ser.http://www.fema.gov/media-library/assets/documents/8811
  8. ^







    FEMA "Emergency Generators Power Town After Sandy Comes Ashore" http://www.fema.gov/news-release/2013/06/21/emergency-generators-power-town-after-sandy-comes-ashore