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Paying and Paying and Paying for a Generator
— continued

[December 26, 2002]

Several respondents said they had owned and used generators for years:

[BF said] "We've had a NG (natural gas) generator for about two years and it has been great. Total cost of generator and installation was $12,000. That included the generator, auto-transfer, electrician, gas line, and enclosure. We couldn't put it on the roof, so it went into a pen behind the building. Two weeks after installation, a dump truck hit a power pole and put us on the generator for eight hours.

You do need a UPS or something to clean the power. We had one system (a workstation) not on the main UPS during one of the generator runs. Now we have a new workstation—a costly error!"

[JP recalled] "We like diesel because you can run it at full load without fluctuations in frequency or output. Engines with less torque don't manage changes in load as well.

A few years ago, we got a Kubota 6500 W diesel which we filled rather quickly to capacity, and that was without air conditioning. I only got to use it for about half a dozen actual outages before we outgrew it.

We've since moved to a new place and put in a 35 kW 3-phase water-cooled Cummins Onan diesel. It's about three times what we need, but we expect to grow and don't want to replace it anytime soon. It was torture getting it off its pallet and into the building in windy snowy weather. We had to take the door frame off the building to get it in. It arrived late, after construction crews had closed the building up.

The generator was not terribly expensive compared to most pieces of combustion-powered machinery of that size. We had to buy a transfer switch, hire an electrician, hire someone to run the fuel lines, hire someone to install the tank, hire someone to build a custom stainless exhaust system, hire a carpenter to build a fire-proof boiler room for the generator, and install louvers for the generator airflow. Then, the people who sold us the generator came in, looked it all over, bled the lines, made a couple of small changes, and fired it up. All told, miscellaneous expenses were as much as the generator.

We have a tank indoors for the fuel and can run for several days at full capacity without refilling. We don't have any natural gas utilities, and since all fuel must be delivered, the choice of what to use is basically the owners. Diesel and propane last for a long time, gasoline doesn't."

[SR commented] "For a datacenter that size it's very cheap to buy a standby generator if natural gas is available.

Please keep in mind that you are looking at an air cooled generator—it's not designed to run continuous duty. A power outage of over 24 hours is going to be pushing what the generator is designed to do. Go to a water cooled same brand and the price jumps to $7,500 instead of $3,100. Go diesel for those that don't have natural gas available and it jumps to about $10,000 for a small unit. The Generac you're looking at is designed for home use, it's not very flexible of a transfer switch.

Now add in on a diesel fuel delivery, filling the tank (filling a 2,500 gallon tank does cost money, and there are other expenses too) and diesel gets much more costly.

Also think about this: if you have natural gas and have a true emergency, will natural gas be available? What's your plan if both aren't available? If you are a dialup provider, then how many customers care during a massive disaster? If you are a hosting company, then your customers don't care why the server is down, they only care it's down.

As was previously mentioned, air conditioning is another concern. It requires a lot of power. If you have natural gas available, consider this: go the next size bigger. I believe generac makes a 22 kW air cooled item that is about the same cost. Talk to an A/C contractor about natural gas fired air conditioning—decide if you want that to be your primary or secondary unit. That eliminates the cost of generator-powering your A/C system Decide if you need the extra level of redundancy of a second generator being diesel powered in the event of a natural gas outage and power outage. Most people play the odds on this and don't get both."

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