We explore the advantages of natural gas-fired microgrids in part four of a six-part Microgrid Knowledge Special Report Series on the affordable microgrid.
Microgrids can use a variety of generation sources: natural gas, diesel, flywheels, fuel cells, energy storage, solar panels and even wind turbines.
Here we look at what natural gas offers in a microgrid that other fuels may not.
Limits of diesel, solar and storage
Because of its widespread availability, diesel has been the traditional solution for engine reliability, whether for backup generators or as part of a resiliency microgrid. But even this workhorse fuel has its limits related to operating cost, availability and environmental impact.
In particular, during Hurricane Harvey the diesel supply chain was extremely challenged. Many of the nation’s largest refineries closed, leading to widespread gasoline and diesel shortages across Texas. Even when diesel was available for purchase, extreme flooding, debris and downed trees and power lines often prevented delivery trucks from reaching sites that had run out of their supply.
Furthermore, when fuel delivery is possible after a major weather event, National Guard units have the right to commandeer fuel trucks destined for commercial and industrial customers.
By the same token, a solar-plus-storage microgrid does not solve the problem. Cloud cover severely limited solar production for five days as Hurricane Harvey battered the Houston area. From a resiliency standpoint, solar panels, even those backed by load-shifting batteries, were not able to perform as first the sun failed and then the batteries.
“A resiliency microgrid has to have an infinite fuel source behind it, otherwise that resiliency is really not there,” said Thomas McAndrew, president and CEO of Enchanted Rock (ERock).
This points to a key advantage of natural gas-fired microgrids over other energy sources during hurricanes, as natural gas is transported by underground pipelines that remain unaffected by severe weather.
While diesel is still the number one microgrid fuel source, natural gas is number two and closing. Specifically, 82 percent of installed capacity is driven by fossil fuels; of this, about 60 percent is diesel and 40 percent is natural gas, according to “US Microgrids 2017: Market Drivers, Analysis and Forecast,” published in November 2017 by GTM Research.
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