Cogeneration is the simultaneous production of electricity and heat from a single fuel source.

Combined Cooling Heating and Power Process Flow

CHP systems are more efficient than traditional energy systems because they capture waste heat, that would otherwise be lost, and use it to provide heating and possibly cooling (if absorption chillers are used).

There are several commercially available CHP technologies, such as microturbines, reciprocating engines, and fuel cells. Microturbines and Reciprocating engines are the most commonly used CHP technologies.

The Department of Energy does a great job of summarizing the different CHP technologies, performance characteristics, and system costs.

Data centers are responsible for over 2% of the world’s electricity consumption and account for 1% of global greenhouse gas emissions. These numbers are only going to grow as data center demand continues to increase, and businesses are looking for ways to reduce the environmental impact of their operations.

In a traditional data center energy system setup, 100% of space cooling fuel is electric energy, space cooling constitutes ~40% of electricity consumption, and 100% of electricity consumption is from a low-efficiency local utility grid system.

Local utility plants can operate inefficiently using carbon-intensive fossil fuels with high transmission losses. Not to mention outages due to scheduled maintenances, extreme weather, or natural disasters. The electric energy delivered to the end-user up lower than 50% efficient. On-premise innovative system designs have to be considered beyond the traditional ways.

CHP systems solve all these issues by taking place of the backup generators, replacing the electric cooling equipment with absorption chillers that consume hot water or steam, and significantly reducing the electric energy consumed from the local utility. CHP systems can achieve efficiencies of up to 95% when properly implemented.

Yes, they could. In data centers, a generator is typically used for backup electricity production during scheduled blackouts and extreme weather conditions, which is an event that happens once or twice a year for a few hours or less.

CHP, however, captures the waste heat from the generator and uses it to provide thermal energy for the data center. So, unlike backup generators, CHP systems must operate more than 5000 hours annually to continuously provide simultaneous electricity, heating, and cooling. This, in turn, reduces the data center downtime and energy/operational costs and increases efficiency and resiliency.

CHP units can be used to fully replace inefficient backup gensets if the data center load profiles (electric, heating, and cooling) allow for it. A proper model of all energy profiles must be accurately analyzed for this to be possible.

As mentioned, IT load is ~50% of a data center’s electricity consumption with all the heat dissipation associated with it. The primary goal of data center air conditioning systems is to keep the servers within the manufacturer’s specified temperature/humidity range.

When absorption chillers are used with a chilled water system design in place of electric air conditioning systems such as electric chillers, computer room air conditioners, or rooftop units, all this electric load is displaced with hot water or steam load, which is perfect for fully taking advantage of the CHP thermal production.

So to answer the question, yes cogeneration can save on data center cooling costs if the cost of electricity is higher than the cost of natural gas or other renewable fuels available. Depending on the utility provider and their tariff structure, the cost of demand charges may outweigh the cost of natural gas charges and savings can be significant.

Yes, CHP systems offer the added benefit of being able to produce electricity from fuels like natural gas, biomass, renewable natural gas, or hydrogen that have lower emissions than the grid average.

Since cooling electricity consumption, and heating equipment energy consumption are significantly reduced, the associated carbon footprint is replaced with the CHP’s footprint. This can be considered emissions savings depending on the average grid emissions and the type of fuel used for the CHP system.

Adding up the emissions from operating backup gensets during outages, the savings can be even bettered.

Incorporating cogeneration into your data center can provide you with a number of benefits, including:

1. Less expensive products, increased access to information, better customer service.
2. Reduced carbon footprint.
3. Increased overall data center energy system efficiency.
4. Increased data center resiliency.
5. Increased data center availability and reduced downtime.

In conclusion, CHP systems are not the only solution for all Data Centers, but when it is the solution for yours, the results are impressive. But just like any construction project, it starts from the conceptual design. The data center electricity, heating, and cooling profiles have to be modeled, analyzed and an optimum CHP system size and configuration must be put in place to maximize energy, cost, and emissions savings. (Check out CogenS^TM, our CHP design, and modeling tool)

If you are interested in learning more about how CHP could work for your data center, you can reach out to us. You can also read more about the subject in this report from the Department of Energy “Opportunities for Combined Heat and Power in Data Centers“.