If you want to go with electric heat, I would build a small electrically heated boiler with the correct amount of heating capacity to match the load of the dryer.
Keith
Commercial/industrial laundries that use steam to heat various appliances (washers, dryers, mangles, hand irons...) usually have two lines. One is incoming steam, the other is to drain away condensate (what forms when steam cools and condenses back to water after giving up heat). That condensate is returned to boiler as water which maintains water level. If this did not happen boiler would constantly require filling with fresh water supplied from taps or other sources. This is not a good thing as fresh water contains lots of oxygen which promotes corrosion inside boiler and piping. OTOH water that is heated has oxygen driven off to various levels. This is why condensate is preferred water source in whole or part.
There is also a valve or something to prevent steam from going down condensate piping or line, but rather remain where it belongs. This is same system used with two pipe steam heating systems.
That condensate has to go somewhere, and said appliances will produce water as steam cools. Dumping it down drains is not only wasteful but leads to issues mentioned above.
Early on "steam laundries" were just that, steam power (generated from boilers) powered machinery (via systems of belts and pulleys), and or was used to generate electricity. Waste steam was used to for heating purposes (ironers, mangles, washing machines, dryers, irons...) after being cleansed of oil, then usually discarded. This more or less is often principle behind district steam heating. Steam used to create electricity via generators is then distributed to an area for heating purposes.
While technology has advanced many laundries still have boilers to produce steam for washers, ironers and so on. This often is largely due to lower cost of natural gas (replacing coal) to heat water into steam as opposed to electricity.
One reason many laundromats (at least in USA) don't use electric to heat water is cost. Other reason going back one or almost two centuries local codes require anyone operating boilers rated above a certain PSI must be licensed/certified which means passing exams and so forth. Steam ships, steam locomotives, boilers in large buildings, boilers in schools, wherever a heating plant had boilers over that number, there you are. Having to hire and keep such boiler trained and certified men on staff is just not a cost many laundromats were or are willing to undertake.
Reason for this is simple: steam boilers if not properly operated and maintained can (and sadly often have) exploded.
https://automaticwasher.org/threads/i-now-own-a-wascomat-washer.99480/#post-1241669
Far as many areas of Europe are concerned even when you see radiators or convectors, it's all hydronic (hot water) heating. Steam in some areas is explicitly banned.
Large or whatever commercial/industrial laundries in USA differ from say those in Europe when it comes to heating wash water.
In USA more often than not hot water is delivered from taps at temps ranging from 140F to 180F. Using multiple wash cycles means by second wash there isn't much dilution from cold laundry thus temps don't drop that much. If necessary say for places processing healthcare laundry machines can be fitted with steam heating to take water up to necessary temp.
Across pond it's usually normal only to heat water far as 140F then use steam (or other means) to heat water up to higher temp if necessary. This is often done in lieu of using multiple wash baths. Rather like domestic European washing machines that start with tap cold or cool water, then heat up to desired temp. Either way this results in longer wash cycles as it takes time for injected steam to bring one to three gallons of water per pound of wash up to temp.
Where a laundry can have natural gas it's usually preferred for at least dryers because of higher temps reached and thus faster cycle times. Same also can apply to ironers where gas heated versions are preferred over steam due to things like higher temps and faster heat recovery times.
