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Take a Fresh Look at Microturbines with CHP
At a recent energy conference, I was struggling to stay awake after several boring presentations – until I heard an update on microturbines. I was so impressed with this presentation that I asked the speaker, Sam Henry of Horizon Power Systems, to collaborate with me on this article and provide a case study.
Before we get into details, let me summarize by saying that microturbines have come a long way in the past five years. They can reduce your lifecycle cost on energy while providing a 20% return on investment. I like that they are plug and play regarding grid integration. They also have improved reliabilities – you can have guaranteed performance and maintenance costs. In addition, microturbines are available in a variety of sizes and can be surprisingly compact. They can be modular with five 200 kW turbines in one package, allowing you to perform maintenance on one unit while the others are running.
The biggest bang for your buck occurs when integrating a microturbine with a combined heat and power (CHP) solution. If you need electricity and have heating needs throughout the year, then you can recover waste heat from a microturbine and be more efficient.
How cost efficient? Well, I have seen a utility that wanted to remain competitive offer an energy user a new, free natural gas boiler to lure the user away from the microturbine/CHP solution! However, even in that case, the microturbine/CHP solution was better and more energy efficient.
To help you evaluate the potential for your facility, this article provides key considerations and a case study.
An Overview of Microturbine Benefits
Microturbines aren’t new technology. They were developed decades ago and have been deployed at thousands of installations worldwide, including manufacturing facilities, hospitals, apartment buildings, oil and gas fields, office buildings, landfills, wastewater treatment plants, and ski resorts. Their benefits include the following:
Lifecycle costs: While other generators may be less expensive to purchase, microturbines’ low lifecycle costs mean a quicker return on investment.
Reliability: Microturbines average 99% uptime, which means near-continuous operation.
Low emissions: Microturbines produce fewer than 9 parts per million NOx, which meets the world’s strictest emission standards. Emissions from microturbines are the lowest among non-catalyzed gas combustion engines.
Modular/Scalable: If a facility requires more power, additional microturbines can easily be paralleled with the original system.
Stand alone or grid integrated: Years ago, the interconnection of microturbines with the grid was a concern. However, today’s microturbines meet global grid-interconnection standards and can work with solar power and other technologies.
On-demand power load: Fluctuations in a facility’s power and thermal needs are common. If demand is low, why pay for power you don’t need? Here’s a scenario: You have a 1 MW microturbine comprised of five 200 kW units in a single enclosure. If the C1000 microturbine is running at 1 MW and the load drops to 600 kW, two microturbines will shut down, turning on later turn if needed.
Fuel: Microturbines will run on many fuels, including natural gas, LPG/CNG, propane, flare gas, landfill gas, digester gas, associated gas at oil and gas sites, diesel, aviation fuel, and kerosene.
Maintenance: With only one moving part and air-bearing technology, there’s no need for oil, grease, or coolants. No storage and disposal of those hazardous materials are required. There are no spark plugs, valves, pistons, cylinders, connecting rods, or other components that need to be maintained or are at risk for failure.
In addition, microturbines have much longer intervals between required services. The first scheduled maintenance occurs after 8,000 hours of runtime – almost a year of continuous operation. Conventional onsite engines typically require initial service at 1,000-2,000 hours, followed by more frequently scheduled maintenance (see table below).
Source: Capstone Turbine
Performance of Microturbines/CHP vs. Conventional Generation
Say your facility needs 65 kW of electricity and 125 kW of hot water. Current power comes from the utility while onsite boilers provide thermal energy for hot water. The efficiency is much higher at 80%, and the microturbine saves fuel and has lower emissions (see table below comparing efficiency and fuel required).
Case Study: An Apartment Complex
An apartment complex installed a combined heat and power system (CHP) anchored by a 1 MW microturbine, which provides about 75% of electricity consumed while the local utility supplies the rest. Heat exchangers capture the microturbine’s waste heat, then use the thermal energy to preheat domestic water that’s supplied to 1,654 apartment units year round. In addition, the waste heat provides primary building heat seven months of the year. Energy efficiencies have soared 80% and more.
Because the CHP system provides more efficient and less expensive energy to the complex than the utility, it’s expected to pay for itself in about four years. In some states, incentives exist to offset purchase and installation costs of microturbines. Check with your state’s Energy Office.
Will CHP Microturbines Work for You?
Consider CHP microturbines if any of the following apply to your facility:
- Per the EPA last year, if you’re paying more than $0.07 per kWh on average for electricity (including generation, transmission, and distribution).
- You have a long-term view for lifecycle savings.
- Your facility is in a deregulated electricity market.
- A loss of utility power would substantially impact business, safety or health.
- Your facility operates more than 5,000 hours per year.
- The facility has thermal loads (steam, hot water) throughout the year.
- You have access to any of these fuels: natural gas, LPG/CNG, propane, flare gas, landfill gas, digester gas, associated gas at oil and gas sites, diesel, aviation fuel, or kerosene.
- You plan to replace, upgrade or retrofit onsite generators or boilers within three to five years.
- You will expand or build a new facility in three to five years.
- Your energy costs remain high even after implementing energy efficiency measures.
- You want to reduce impact on the environment.
Thanks to Sam Henry, President of Horizon Power Systems, and Cory Glick, President of RSP Systems, for assisting with this article. Their companies are authorized Capstone Turbine distributors. Horizon serves the Rocky Mountains, Gulf Coast and Western Canada. RSP serves Greater New York and Connecticut. For questions in their respective territories, contact Henry at firstname.lastname@example.org and Glick at coryg@cogenNYC.com.
Eric A. Woodroof, Ph.D., is the Chairman of the Board for the Certified Carbon Reduction Manager (CRM) program and he has been a board member of the Certified Energy Manager (CEM) Program since 1999. His clients include government agencies, airports, utilities, cities, universities and foreign governments. Private clients include IBM, Pepsi, GM, Verizon, Hertz, Visteon, JP Morgan-Chase, and Lockheed Martin. In August 2014, he was named to the Association of Energy Engineers (AEE) Energy Managers Hall of Fame.