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Nel Hydrogen in the Southeast

PEM and alkaline electrolysers that produce high-purity hydrogen on site, from compact generators to 100 MW-class plants.

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Headquarters: Wallingford, CT (US) · Oslo, Norway (Nel ASA)
Founded: 1996
Parent: Nel ASA
Coverage: All Vaughn Associates territories

About Nel Hydrogen

Nel Hydrogen is the electrolyser business of Nel ASA, a company listed on the Oslo Stock Exchange and one of the longest-running makers of water electrolysis equipment. Its North American operation in Wallingford, Connecticut, is the former Proton OnSite, founded in 1996 as Proton Energy Systems and acquired by Nel in 2017. The US company now trades as Nel Hydrogen US.

Wallingford has built proton exchange membrane (PEM) hydrogen generators for about 30 years. Nel opened an expanded, automated PEM factory there in October 2024 and says the facility can build about ten times as many electrolysers at roughly 30% lower cost.

What Nel Hydrogen makes

For most plant engineers, Nel means self-contained PEM generators that turn deionized water and electricity into dry, high-purity hydrogen at the point of use:

S Series (S10, S20, S40): compact, air-cooled units delivering 99.999%+ purity for laboratories and light industry.
H Series (H2, H4, H6): 2–6 Nm³/h generators that follow demand and serve as Nel’s lead product for generator cooling.
C Series (C10, C20, C30): the largest packaged units, delivering 30 barg without an added compressor.

At larger scale, containerized MC Series electrolysers span 1.25–20 MW, and the PSM Series builds on 10 MW PEM blocks. On the alkaline side, the atmospheric A-Series targets low energy use, and the pressurized PA-Series, launched in May 2026, is aimed at green steel, ammonia and sustainable aviation fuel.

Nel has narrowed its focus to electrolysers. It stopped making Proton’s benchtop laboratory generators in 2020 and spun off its fueling business as Cavendish Hydrogen in 2024.

Why engineers specify Nel Hydrogen

Fewer deliveries. On-site generation reduces cylinder changeouts, tube-trailer deliveries and bulk hydrogen storage.
Dry, pure gas. PEM units use only deionized water, with no liquid caustic, and H Series generators deliver a dew point of −65 °C or lower.
Demand-matched output. Automatic load following keeps production aligned with consumption.
Certified management systems. Nel reports certification to ISO 9001, ISO 14001 and ISO 45001, supported by factory and field service.

Local support from Vaughn Associates

Hydrogen users across the Southeast include utility generating stations, heat-treating and sintering operations, glass and electronics manufacturers, and analytical laboratories. Vaughn Associates helps these teams evaluate whether on-site generation makes sense, gather flow, purity, pressure and consumption data, and coordinate sizing and quotes with Nel’s factory team.

Vaughn covers Nel Hydrogen in all of its territories, and we stay involved from the first application review through delivery.

Request application help, learn more about on-site hydrogen generators, or find your local rep.

About three decades of PEM electrolyser production in Wallingford, CT

PEM and alkaline technologies in one portfolio

Load-following output reduces on-site hydrogen storage

Dry, high-purity hydrogen from deionized water with no caustic in PEM units

Global factory and field service

Product lines

What Nel makes — product categories we can help you specify.

Compact on-site hydrogen generators (S Series)

Air-cooled, single-phase PEM units for laboratories and light industrial use that deliver 99.999%+ purity while storing less than 300 mL of gas.

Mid-range industrial hydrogen generators (H Series)

Factory-built PEM generators that follow demand from 0 to 100% with a dew point of −65 °C or lower; Nel's lead product for power-plant generator cooling.

High-output packaged generators (C Series)

The largest self-contained PEM units, delivering hydrogen at 30 barg without an added compressor and integrating with plant controls through an onboard PLC.

Containerized MW-scale PEM electrolysers (MC Series)

Outdoor 20-ft and 40-ft container systems from 1.25 to 20 MW with fast ramping for renewable-powered hydrogen production.

MC250
MC500
MC1000
MC2000
MC4000

Large-scale PEM platform (PSM Series)

Modular 10 MW PEM blocks that ship largely factory-complete, allowing customers to supply their own balance of plant for very large projects.

PSM
PEM 100

Atmospheric alkaline electrolysers (A-Series)

Low-pressure alkaline systems focused on low energy consumption, with stacks designed to be serviced over a long operating life.

A485
AWE100

Pressurized alkaline electrolysers (PA-Series)

A containerized alkaline platform launched commercially in May 2026, built in 25 MW blocks for green steel, ammonia and sustainable aviation fuel projects.

PA-Series 25 MW building block

Service and remote monitoring

Factory phone support, field service engineers, commissioning and training, plus plant monitoring through the Nel After Sales Operations Center.

NASOC

Applications

Hydrogen cooling for power-plant generators
Reducing atmospheres for annealing, sintering and brazing
Metal additive manufacturing
Float glass production
Semiconductor process hydrogen
GC carrier and FID fuel gas
Renewable-powered green hydrogen production
Green hydrogen for steel, ammonia and sustainable aviation fuel

Standards & certifications

ISO 9001:2015
ISO 14001:2015
ISO 45001:2018

FAQ

Common questions about Nel

Is Proton OnSite still in business?

Proton OnSite is now Nel Hydrogen. Nel ASA of Norway acquired Proton Energy Systems, which did business as Proton OnSite, in a deal that closed on June 30, 2017. The US company now trades as Nel Hydrogen US from the same Wallingford, Connecticut campus, which Nel expanded and automated in 2024. The Proton OnSite name has been retired, and protononsite.com redirects to Nel's support page.

Can I still buy a Proton OnSite laboratory hydrogen generator?

No. Nel stopped manufacturing Proton OnSite's benchtop laboratory hydrogen and nitrogen generators in October 2020, and in December 2021 support, spare parts and field service for those units moved to Gas Generator Solutions. Labs that still want on-site hydrogen for multiple gas chromatographs can consider Nel's S Series, which produces up to 1.05 Nm³/h at 99.999%+ purity and can supply many instruments from one unit.

How do I size a hydrogen generator for power-plant generator cooling?

Start with the generator's hydrogen makeup (leak) rate, purge requirements, and required purity and pressure. Makeup demand is usually modest, so Nel's H Series, rated 2–6 Nm³/h, is its usual recommendation, with S or C Series units for smaller or larger needs. Load-following output keeps production matched to demand and reduces the amount of hydrogen stored on site.

What is the difference between PEM and alkaline electrolysers?

Alkaline electrolysers, such as Nel's A-Series and PA-Series, use a liquid potassium hydroxide electrolyte and are mature, efficient choices for steady, large-scale output like green steel or ammonia. PEM units, including the S, H, C, MC and PSM Series, use a solid polymer membrane. They ramp faster, take less floor space and produce higher-purity hydrogen, which suits point-of-use industrial and lab supply.

Does Nel still build hydrogen fueling stations?

No. Nel spun off its fueling division as a separate listed company, Cavendish Hydrogen ASA, in June 2024, and Nel shareholders received shares in the new company. Cavendish, based in Denmark, now develops and sells vehicle refueling equipment. Nel itself focuses on electrolysers, from compact on-site hydrogen generators up to 100 MW-class systems.

Who represents Nel Hydrogen in the Southeast?

Vaughn Associates, Inc., an independent manufacturer's representative headquartered in Huntsville, Alabama, with an office in Baton Rouge, Louisiana, represents Nel Hydrogen in all of its territories. Vaughn's engineers help utilities, thermal processors and laboratories evaluate on-site generation, gather flow, purity and pressure requirements, and coordinate sizing and quotes with Nel's factory team.

Local support

Territory map