The Paris Compressed-Air Power Network

Gallery opened 9 Jan 2018

Updated: 15 Jan 2018

Air-motor system added
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The city of Paris once had an extensive network for distributing power by compressed air. London, Manchester, and Liverpool had hydraulic power distribution networks, and there were others in Antwerp, Australia and Buenos Aires, but the compressed air network of Paris was unique. Attempts were made to set up a network in Birmingham, but these failed.

There is an immdiate objection; transmitting power by compressed air is horribly inefficent, because all the heat created in the compressor is lost long before the air gets to the point of use. Nonetheless the Paris network flourished for many years. Factory-wide compressed air networks for driving power tools are commonplace, but only Paris had a city-wide network.

The roots of the system go back to 1879 when the Austrian engineer Viktor Popp set up the Compagnie des Horloges Pneumatiques (CGHP)to drive pneumatic public clocks with one air pulse per minute, after authorization to install a compressed air network was granted by the City of Paris.

At the time compressed air was in the air, so to speak, following the extensive use of compressed air for rock drilling in the construction of the Mont Cenis tunnel, which was initially expected to take 25 years but was opened in 1871 after only 14 years following the introduction of pneumatic equipment. (Dynamite was also a help in the later years of construction) At the time there was much debate as to the best way of transmitting power over a distance; electricity was in its infancy, but high-pressure water had proved highly successful

Popp obtained French nationality in 1881. In 1886 he was licensed to distribute compressed air continuously as a general source of motive power. In 1889 he obtained a further municipal concession to supply electricity by using the compressed air power network to drive local electrical generators. Large amounts of power were handled by converted steam engines, but small amounts by a rotary air engine introduced by Popp; all attempts to get any more information on this intriguing device have so far failed. Help!

For several years Popp ran the company as director of the Compagnie Parisienne de l'Air Comprime. (CPAC) However in 1892 the German banks who had provided most of the capital for the rapid expansion of the power network took over control, and Popp was forced to resign. (The involvement of the Germans did not sit well with the French, who had not forgotten the Franco-Prussian war) He then turned his attentions to compressed-air traction, and the growing motor industry. Popp was later involved in the Branly-Popp radio system.

In 1888 Viktor Popp installed a 1,500 kW compressor plant at 16 Rue St-Fargeau, in Belleville, a district in the north-east of Paris. That grew to 18,000 kW by 1891. Another usine (power-house) was built later at Quai de La Gare.

Left: The Paris compressed air network: 1891

The original Rue St-Fargeau compressing station is at top right. The location seems to have been dubiously chosen as it had no direct rail access for delivering coal; this presumably came by cart from the nearest railway which was the Petit Ceinture, but old maps show no nearby goods yard. Cooling water for the condensers presumably came from the nearby Menilmontant reservoir, which was fed by the Dhuis Aqueduct; this was not an aqueduct carried on arches but an oval masonry conduit running underground.

The later Quai de La Gare usine was built adjacent to both the Ceinture (for coal) and the Seine. (for water)

The bobbly line is the the defensive Thiers wall built around Paris between 1841 and 1844. It was demolished in sections between 1919 and 1929.

Note that this map appears to show the Petit Ceinture ending at the Cemetery Pere Lachaise; actually it went (and indeed goes, though the line is disused) underground at this point.

Left: The St-Fargeau usine: 1889

This shows a row of horizontal steam-driven compressors. The steam cylinders and flywheels are on the left and the compressor cylinders and air reservoirs on the right. The air was compressed to six atmospheres. (88 psi)

The boilers were in an adjacent hall to the left, and the steam pipes coming horizontally through the wall before dropping down to the engines are clearly visible.

Usine roughly means 'power-house'.

From The Manufacturer and Builder, July (?) 1889, p135. Courtesy Tom Bates

Left: The boilers at the St-Fargeau usine: 1889

There are nine Paxman 'Economic' return-flue double-furnace boilers nearest the viewer. The boilers were 14 foot long and 7' 6" in diameter. Paxman was a British firm and this caused trouble later as people thought the machinery should be made in France. At the far end were two boilers of the Meunier type.

Three of the safety valves appear to be blowing off- a waste of steam and surely a hazard to the chap standing on top of the boilers. The boiler feed pumps can be seen at bottom right.

Running along the back of the boilers is the steam range- a large pipe collecting the steam from each boiler and distributing it to the engines so any combination of boilers and engines could be shut down as required for maintenance.

At the extreme left coal is brought in in tipping-wagons and placed in a long heap on the floor for the stokers.

From The Manufacturer and Builder, August 1889, p182. Courtesy Tom Bates

Left: Air-motor system with gas reheater: 1889

This is a typical compressed-air installation for generating a modest amount of electricity; enough for one establishment. The air engine is indistinguishable from a steam engine, which it may have been at an earlier stage in its career; it has a conventional speed governor that works by throttling the incoming air.

The air enters the premises at the right, its delivery being controlled by valve controlled by a spring and a weight; quite how this functioned is not currently known. From there the air passed into the reheater, where a gas-ring heated the air pipe. This extracted much more power from the air (which had lost its heat of compression) and also prevented the engine from freezing up. A small Gramme dynamo is driven by belt from the engine. It seems ironical that the compressed-air system could not be used effectively unless gas was also available. Coke-fired reheaters could also be used but were much messier.

In some cases the amount of reheat was limited so that cold air came out of the engine, and this was used for cooling beer, etc.

From The Manufacturer and Builder, August 1889, p183. Courtesy Tom Bates

Left: First page from a 'Diverses Applications de L'Air Comprime et de Electricite' 1888

This is the first page from a 'Diverses Applications de L'Air Comprime et de Electricite' published by Popp, which lists the Paris air installations as of 1st October 1888. It lists the name and address of each user, and gives a unique insight into the wide variety of ways that the compressed-air supply was used.

In the first section, each of the 'Stations Centrales' had a compressed-air engine driving an electrical generator for public supply; these were steam engines with some minor modifications. The total of 750 horsepower is equivalent to 560 kW. This may not seem much electric power for a city the size of Paris, but most of it was used for lighting rather than power.

The second section deals with compressed-air electricity generators for single enterprises; thus the Figaro newspaper had its own 45 horsepower (33 kW) engine. The Figaro manager wrote: "The service leaves nothing to be desired, and we only have to congratulate ourselves on daily reports with the administration of Mr. Victor Popp ". At least that's the version provided by Google Translate.

In 1949 CPAC became the Société Urbaine de Distribution d'Air Comprimé. (SUDAC)

SUDAC decided to build a third power station in Aubervilliers in 1959. It opened in 1961.

By the end of the 1960's the amount of industry in Paris was decreasing rapidly. The company still exists as SUDAC though it now supplies factory compressed-air plants; the first of these was installed in 1973.

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