Data centers deliver business continuity towards her customers, often supported by a service level agreement (SLA). One of the things with a guaranteed uptime is power. To make sure a data center can provide power during a power outage a backup generator is one of the most important components at a data center. And what about the most critical requirements for a generator, and how can it impact the continuity? You know what I’m talking about; fuel!
Diesel and GTL
Backup generators require fuel to operate. Basically, there are 2 types of fuels available on the market:
- Liquid fuel is the most common type of fuel;
- Gas is not very common but not unusual (therefore excluded from this blog).
Backup generators placed at a data center often requires diesel fuel to operate; diesel is not one of the cleanest fuels in the market. An alternative for diesel fuel would be GTL (Gas to Liquid), this is a special fuel created when Methane-rich gasses are converted into liquid synthetic fuels. GTL is cleaner when comparing to diesel fuel obtained from petroleum. GTL has a couple of downsides; it is more expensive then Diesel, not all engine manufacturers allow the use of GTL because it is a “dry” type of fuel which means it does not lubricate the engines mechanical parts like diesel does, and it is not as easy to get compared to diesel.
Diesel fuel needs to be stored onsite in large quantities to guarantee a certain runtime for the generators calculated on full load; a power issue needs to be survived and it must be possible to obtain diesel fuel in case of a long term usage of the generator. Generators typically have a, so-called, day tank which offers fuel for a couple of hours. This day tank needs to be refilled by a main bulk tank on-site, the refilling is arranged by a refuelling system which opens and closes valves between the day and bulk tank. The diesel fuel stored onsite needs to comply to local law and legislations. One of the requirements to comply to law is legislation is the need to have the fuel storage inspected and approved by specific authorities periodically.
Diesel stored in the tanks can get old or contaminated over time, contamination happens over time when using “regular” diesel which you use to fill up your car. This fuel has an amount of bio fuel added. Bio fuel is made from organic materials and can get contaminated by fungi, yeast and bacteria such as algae. These contaminations can block the fuel filters of a generator. A contaminated fuel filter can cause failures and hitches to the backup generator. Data centers can choose to buy fuel without bio diesel to lower the changes of getting contaminations. To eliminate the risk of contaminated fuel completely, tanks can be equipped with a fuel polishing system. A fuel polishing system actively filters fuel and removes any type of contaminations. It is still recommended to test the fuel and change the fuel filters every year.
Fuel tanks need to be refueled once in a while, advised is to refuel a tank when reaching 75% or before a planned event which requires to run on generator for a longer period of time. To get the required fuel a data center usually has one or more contracts with one or more fuel companies. These contracts normally includes an SLA between the data center and the supplier that states the maximum time for the fuel company to get onsite and start refuelling.
A commonly heard rumour is that a data center buys their fuel very cheap because of the amount of fuel, however, sadly this is not true. The fuel itself is cheaper, when including all the costs, like transport, labor of the truck and other environmental costs there is no difference.
Fuel is an important part in the requirements of a data center. Without fuel it is not possible to perform maintenance to some critical parts of the electrical system and main grid failures are not backed up. Having a safe and steady fuel system is key towards the success of a data center. A fuel system needs to be in place to safeguard operation of your data center and proper fuel management is required to eliminate the risk of failures and hitches, you don’t want people refuelling by hand using jerry cans when having an outage.
At Datacenter.com we have a dedicated fuel tank per power feed which is connected to the generator. An issue in one of the fuel systems does not impact the other generator, therefore safeguarding the continuous power supply towards the data center. Sadly, I cannot collect airmiles when refuelling. 😉