In the days before natural gas was piped into communities, gas lighting and heating used “manufactured gas” – made by burning and processing coal, and sometimes oil. Most communities had their own Manufactured Gas Plant, because it wasn’t easily transported in the days before sealed long-distance pipelines and trucks.
So how did they store the gas? By bubbling it through water and putting it underneath a floating upside-down cup – a cup that, in the case of the gas-holder site in Concord, was a riveted-steel structure 80 feet in diameter, which floated up and down by as much as 24 feet, rising up to cover the windows shown in the photo above. It’s a very cool technology called a gas holder; I discuss in in a Concord Monitor story today in this sidebar.
Many Manufactured-Gas Plant sites are very polluted from process residue, notably coal tar, which is why the EPA is involved. Concord’s MGP site is special, perhaps unique in the country, because the round brick house that covered the gas holder is still intact, although in crummy shape. It’s a gorgeous, interesting building, as Geoff Forester’s photos show (one of them is above) – it’s clear whether anybody wants to spend the money to save it, but I hope they do. Here’s the main story about the building.
Return to the Concord Monitor
The Concord MGP gasholder house, though rare, is not unique in the country. Examples still exist, such as those in Troy, NY (Jefferson Street & Fifth Avenue), Batavia, NY (Evans St.), Woonsocket, RI (Pond St), two in North Attleborough, MA (East and Elm Sts., and Elm and Mt. Hope Sts.), Olneyville, RI (Aleppo St.), Northampton, MA (Roundhouse Plaza), and Oberlin, OH (S. Main and Essex Sts.). All of these are visible using Google Maps and Street View.
Some of the technical details in the articles are a bit off. Coal was not burned to make the gas. Instead, it was heated in a sealed vessel (think of an airtight oven, called a “retort”) to evolve the gasses from it. That process was used in Concord until around 1894, when a newer process typically using coke, steam and oil supplanted the old coal gas process and was used until gas making stopped in 1952.
Gas was not bubbled up through the water in the underground tank. The gas inlet and outlet pipes went through the foundation of the tank, up through the water in the tank, and opened above the waterline.
The “cup” (known as the “bell,” “lift” or “holder”) did not really float. Instead, it rose and fell depending on the pressure of the gas inside. The more gas forced into the tank, the higher it rose. Gas did not need to be pumped out, because the weight of the iron holder was sufficient to provide pressure for distribution of the gas.
The larger “metal tank” gas holder (1921) next to the one in the holder house (1888) was not “sealed.” That later technology used an above-ground steel water tank, as opposed to an in-ground brick water tank, but the water tanks in both were still open to the atmosphere. The 1921 holder at Concord was much too large to practically fit inside a building. (The 1888 holder held 120,000 c.f. of gas and the 1921 holder held 500,000 c.f., using three concentric lifts.) But by then buildings were not necessary because the industry had figured out how to stop the tanks from freezing-up when exposed to the elements by, for example, the use of steam.
I cannot comment on the accuracy of the attribution of the crooked cupola to “twisting” of the structure, but my understanding was that it became crooked as a result of the 1938 hurricane. I recall seeing historic photographs showing the cupola post-storm and attributing the movement to wind damage.