LIBERTY UTILITIES TARGETS KEENE
"The plan is to eventually have a permanent natural gas plant in Keene to replace the city’s decades-old propane-air system.
But for now, Liberty Utilities officials are looking at a temporary solution.
They recently submitted an application to the Keene Planning Board to install a temporary natural gas facility at 43 Production Ave. before the end of 2017.
Plans call for the plant to include a modular decompression skid and associated equipment to decompress the compressed natural gas being delivered by tanker trucks to the facility. A modular decompression skid lowers the pressure of natural gas before it is distributed.
Underground piping would be installed to carry the natural gas to Liberty Utilities’ existing pipeline along Production Avenue, the application says.
From there, the gas would go to businesses on Production Avenue and then under Route 9 to the Monadnock Marketplace.
A generator would be installed to keep the facility running during a power outage, the application says.
Liberty Utilities proposes installing the temporary plant as part of the first phase of converting its Keene customers to compressed natural gas, spokesman John Shore said in an email.
That phase involves getting the system’s commercial customers at Monadnock Marketplace on to compressed natural gas, he said. Eventually, customers elsewhere in the city will also be put on the new system, he said.
“Once these commercial customers have been converted, we will work on the permanent facility, and begin to convert the remaining air-propane customers in phases over the next several years,” he said.
Compressed natural gas is mostly made of methane and is used as a cleaner and more efficient alternative to other fossil fuels. Unlike the propane-air combination, it doesn’t require mixing.
There are several reasons Liberty seeks to switch from propane-air to natural gas, including that Keene’s current system is an unusual one, Shore said.
“Anyone connecting to it with an appliance or other equipment needs to have that piece of equipment modified to work on our system,” he said. “This makes things difficult for our customers. Switching to natural gas will eliminate that equipment modification requirement.”
It would also make the system more reliable, he said.
Liberty Utilities would also be able to retire its air-blower system, Shore said. In December 2015, a glitch in this system caused by a power outage led to pure propane being sent out to Keene customers, rather than the proper mixture of propane and air. Improperly mixed propane can produce carbon monoxide.
The incident spanned 15 hours and caused four people to be sent to the hospital with symptoms of carbon monoxide poisoning. The response involved 64 fire and emergency medical services departments from New Hampshire, Vermont and Massachusetts, as well as 12 local, regional, state and private agencies.
A similar problem happened in February 2016, but on a much smaller scale as safety measures put in place after the previous incident were able to correct the problem immediately.
The part of the propane-air system serving residential areas operates at a very low pressure, which is adequate for most customers and doesn’t require the air-blowers, Shore said.
However, some commercial customers require higher pressure to meet their heating and cooking needs, which is why the air-blower system is necessary, he said.
Liberty Utilities bought the air-propane system and other assets from Keene-based N.H. Gas Corp. in 2014. The city’s system has 1,250 residential and commercial customers.
The production facility for the air-propane system on Emerald Street was built around 1860, but the equipment in the facility that produces the fuel provided to customers was installed in 1971, Shore said.
Of the 30 miles of gas main in the city, about 9 miles is old cast iron or steel piping that was installed in the 1930s and ‘40s, he said.
“We plan to replace a minimum of 1500 (feet) of old gas main this year and will continue to replace old main pipes as opportunities arise,” he said in an email.
The rest of the pipeline infrastructure is modern plastic pipe, he said."
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