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Hydrogen backup or a diesel generator: an honest comparison

Diesel generators are proven, widely available and cheap to buy. The case for stored hydrogen is about what happens on day four of an outage, not about price.

Where diesel wins

A diesel generator is available now, any mechanic can service one, and diesel holds a lot of energy in a small tank. If you can get fuel delivered, a diesel set will run for as long as the fuel lasts. Hydrogen backup, by contrast, is still in development, with no price yet, and round-trip efficiency of 30% or less. If your priority is the lowest upfront cost today, diesel is hard to beat.

What it would keep running

  • House essentials with no fuel deliveries
  • Freezer and fridge through a long outage
  • Modem kept up without a restart
  • Water pump
  • Night lighting with no engine noise

Where diesel struggles

Diesel has to be bought, carted and stored, and in a regional emergency the road to the fuel stop may be shut. Stored diesel can degrade and grow microbial contamination if it sits for a long time. Generators need regular test runs, are loud enough to bother neighbours, and produce exhaust that must never get into the house. Most also take time to start, so the house blinks off before power returns.

A diesel set that has not been started for months also has a habit of failing at the exact moment it is needed, with a flat starter battery, a blocked filter or water in the fuel. Keeping one reliable means a routine of test runs, fuel treatment and servicing that many busy households let slide.

How it works →
The H2OME loop: an electrolyser splits water into hydrogen, the hydrogen is stored in a tank for weeks, a fuel cell turns it into electricity for your home, and the water returns to the loop.

What hydrogen changes

A stored hydrogen system makes its own fuel from night-rate power, wind or micro-hydro and water, so there is no fuel run. The fuel cell is quiet with no engine, and its by-product is water. The battery and inverter switch over instantly in UPS mode, so nothing resets. The trade-off is efficiency and the fact that storage, once used, only refills when you can charge again.

Questions

Is hydrogen cheaper to run than diesel?

We will not claim that. Round-trip efficiency is 30% or less, so each stored kilowatt hour costs several kilowatt hours of night-rate power. Whether that beats diesel depends on your tariff and diesel prices. The case for hydrogen is fuel independence and no fumes, not cheap energy.

Can I keep my diesel generator as well?

Many people will, at least while hydrogen backup is new. A generator can be a last resort if storage runs out in a very long outage. Any second supply must be connected by an electrician so the two never feed each other or the grid.

Does a diesel generator need to run regularly?

Most manufacturers recommend periodic test runs under load to keep the engine and fuel healthy. That costs fuel and makes noise. A hydrogen system has no engine to exercise, though it still needs its own scheduled checks.

More in outages, weather and how it works

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