July 1st - Combining Heat & Power in the Data Center

Combined heat and power or CHP plants have been around since the 1800s and since, the technology hasn’t changed a lot. However, contrary to what you may think, that doesn’t mean that they can’t offer some serious benefits as the primary source of power in modern data centers. In fact, this age-old technology is already used extensively in hospitals, refineries and biotech facilities, so maybe its time for data center operators to get with the times and adopt CHPs.

It’s common knowledge that data centers require a lot of energy to run their UPS, servers, and storage arrays, and many data centers also require large quantities of chilled water to cool their servers. According to Terence Waldron, president at Waldron Engineering and Construction, who spoke about the use of combined heat and power plants (CHPs) in data centers Tuesday at the Data Center World conference in Las Vegas, that’s where the beauty of CHP plants really comes to fruition. The key is to combine the combined heat and power engine with an absorption chiller to maximize the energy benefits for the data center.

CHP engines are about 40% efficient when they convert fuel to energy, which may sound sub-par but actually, the average energy utility is usually only about 33% efficient. The remaining 60% of that energy is converted to heat which an absorption chiller converts into chilled water. Coincidentally, the absorption chiller typically produces an amount of chilled water that’s equivalent to the amount needed to cool the servers in its respective data center. As Terence Waldron put it, “It’s an interesting balance,” he said. “No one designed the engine in that way. It just happened that way.” By essentially converting all of the energy loss to chilled water, data center operators can reap huge energy efficiency benefits while significantly reducing their carbon footprints.

There is a drawback, however. Opting for the CHP solution could cost you more upfront due to the CHP cost and maintenance costs, as well as potentially higher utility rates since running a CHP classifies you as a poor load factor client to the utility companies due to your now more efficient but, more sporadic utility load. Instead of a constant, steady load, with a CHP it will now fluctuate greatly depending on the time of day and operation in place. However, even with these drawbacks, a CHP will eventually pay for itself. While the payback is typically a little over 4 years, it should be noted that the overall value of these utility projects can last for a lifetime once the payback is fulfilled.