The power is back on in most of Manhattan, but neighbouring authorities are still working to re-connect their customers – the Long  Island Power Authority says it will have re-connected 90% of customers by Wednesday.

Around 3 million homes in north-east US remain without electricity a full week after hurricane Sandy’s destructive journey across the north-eastern corner of the US.

It doesn’t happen often, thankfully, but Sandy has revealed once again a vital additional advantage for operators of commercial buildings that have their own on-site power supplies. Additional, that is, to the more obvious cost and environmental advantages, particularly when power is generated alongside heat in a high efficiency CHP/cogeneration plant.

Hospitals and university campuses are particularly well-suited to CHP and many of these facilities were able to keep most of the lights on even as utility power feeds were cut last week. CHP plants cannot survive major flooding incidents any more than other types of electrical equipment.

But buildings with their own on-site generation can, if the generation plant is configured appropriately, continue to operate during utility power cuts.

The on-site generation plant may only serve a proportion of the overall electrical loads – pre-identified essential loads – but, in a hospital this can mean the difference between staying open, and shipping patients out.

Of course stand-by generators are also designed to keep vital electrical loads supplied in emergencies, but operators of buildings that run their own energy systems every day are in a more secure position, and can often keep a higher proportion of site loads supplied during interruptions.

Microturbine energy systems manufacturer Capstone reports that its on-site power plants, which serve hotels, data centres and health care facilities from Virginia to New Jersey, operated ‘seamlessly’ during the storm. One installation played a crucial role – Salem Community College in New Jersey also operates as a Red Cross Disaster Relief Shelter and was able to stay fully open due to its microturbine-based heat and power supply system.

Capstone’s Mid-Atlantic distributor lost its utility power but operated its monitoring and data gathering services without interruption with the help of its own on-site power system.

Also in New Jersey, cogeneration equipment at Princeton College kept that site open throughout the incident – see the College’s video on YouTube to see how.

It’s not the main selling point, but the ability to stay open for business during power outages is an additional, powerful argument for on-site CHP/cogeneration.

Steve Hodgson