Natural Gas Helps Keep the Lights On
- Combined heat and power systems can provide power during an outage.
- Other benefits include reduced costs and lower emissions.
- System efficiencies of above 90 percent are possible.
When the next Superstorm Sandy comes around, some commercial and industrial facilities won't have to worry about losing power and the subsequent revenue loss. Why? Facilities who have installed cogeneration (combined heat and power) systems know they have a reliable source of power when fueled with natural gas.
And with climate experts predicting the weather is only going to get worse, you may want to consider following these five examples:
1. Aberdeen Proving Ground
in Maryland is improving its military preparedness with a 7.9-MW natural gas CHP system, which is replacing a steam generation plant being decommissioned in 2016. The new system will provide 86 percent of the site’s steam supply and offset 50 percent of current electricity use, saving the U.S. Army around $4.4 million per year. Energy resiliency is the name of the game and the CHP system is playing a major role.
2. Patients at the Upper Chesapeake Medical Center (Bel Air, Md) are remaining safe and healthy because of an on-site CHP system, which serves as the primary power source for the hospital’s electrical load. The system consists of a 2-MW natural gas fired generator, a 350-ton absorption chiller, a heat recovery steam generator, and other equipment. The steam converted from waste heat is utilized in the absorption chiller, building steam loop and converted for use in other hydronic systems. During a prolonged outage, the CHP and the existing hospital emergency generator can maintain more than 60 percent of the loads.
3. The Horseshoe Casino in Baltimore, Md., the second largest in the state, is betting on its trigeneration system to provide a significant portion of the $442 million development’s energy, heating and cooling needs. The system, optimized for natural gas use, produces 1,149 kW of electricity and 4.1 million Btu’s of heat per hour. Total system efficiency is between 88 and 92 percent. In addition, the system will help the casino reduce its carbon dioxide emissions by up to 50 percent.
4. A $96 million CHP plant under construction at the University of Minnesota will help protect hundreds of millions of dollars of research in the event of a catastrophe. In 2007, a nearby freeway bridge collapsed, threatening the tunnel that supplied the university's steam. The plant will include two 7-MW gas-fired turbines and heat recovery steam generators, generating enough steam to heat the entire campus and cover around half of its electricity demand. In addition to improving the campus' energy reliability, the plant reduces the campus carbon footprint by 10 percent and annual utility costs by an estimated $1.9 million.
5. National Gypsum's wallboard manufacturing facility at Burlington, NJ won't have to worry about production downtime with its CHP gas turbine system. The project produces 3.4 MW of electricity and delivers more than 30 MMBtu of thermal energy each hour of operation, resulting in an overall efficiency of greater than 90 percent. The turbine's waste heat is used for the dryer.
To operate during a utility system outage, remember your CHP system must have:
- Black start capability, in which an electrical signal from an on-site battery or backup generator turns on the CHP system when there is an outage and the CHP system isn't operating
- Electric generator with inverter, which conditions the power to make it suitable for interconnection to the local utility grid.
- Transfer switch safeguards for synchronous generators, which ensures the CHP system can't export power to the unpowered grid while down, which could injure utility personnel or equipment.
- Parallel utility interconnection and switchgear control to shut down non-critical loads and prevent overloading the generator capacity.
Also keep in mind you must determine the size of the CHP system during the design stage. Do you want to size the system to just handle critical loads during a power outage or to handle all of your facility's electrical requirements? In the latter case, excess power would be exported to the powered grid when operating at partial load.
To determine if CHP is right for your facility, download this screening tool from Oak Ridge National Laboratory. RETScreen software from Natural Resources Canada can also help you determine the technical and financial feasability of CHP projects.