Managing energy in large buildings and campus complexes is an undeniable challenge. Optimizing efficiency, ensuring maximum reliability, and adhering to a budget are all critical pieces of any successful energy management system. Mission-critical buildings, such as those operated by hospitals, data centers, industrial, and manufacturing facilities, and public transportation operators have the added challenge that their facility functionality is essential to their business, and no margin of error in energy management is acceptable. Mission-critical facilities must have reliable sources of energy, along with seamless contingency plans that implement automatically when primary service interruptions occur.
With mission-critical buildings, maintaining a continuous supply of electricity, as well as thermal energy for heating and cooling, is of paramount importance. Traditionally, mission-critical buildings have received power from the electric grid via fossil-fueled or electrically driven boilers and chillers. Onsite for heating and cooling purposes, these boilers and chillers have relied on fossil-fueled backup generation in the event of a grid outage, which is a model that has resulted in relatively low energy efficiency rates.
With an aging national energy infrastructure, the prolonged economic crisis we are currently experiencing, unpredictable and volatile energy markets, and a series of new mandates dedicated to curbing greenhouse gas and carbon emissions, today’s businesses are scrutinizing every aspect of their operations and are asking where they can create efficiencies and implement improvements. Energy management is an area in which companies can experience simultaneous improvements in both their economic and environmental performance.
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Photo: Veolia Energy
CHP and district energy are naturally complementary. |
Over the last decade or so, the deregulation of several energy markets in the US has resulted in the proliferation of energy services companies that tout solutions to address energy management. At the same time, regulatory developments are driving further change that have resulted in new challenges and opportunities on issues as diverse as demand response, onsite generation, and carbon footprints.
Because of these factors, and the changing tide of energy management, managers of mission-critical buildings often have to evaluate a myriad of options before they can determine the best fit for their organization. Some of the solutions advocated by energy services providers are new and cutting edge, while others are tried and true energy management tactics that, when coupled with modern performance management systems, can be viable and reliable solutions.
Mitigating Risk Through Onsite Generation: The Case for CHP
One proven energy management solution for mission-critical buildings is the implementation of Combined Heat and Power (also known as CHP, cogeneration, and cogen), which is the use of a power generation plant to simultaneously generate both heat and electricity. Traditional power plants do not convert all of their available energy into electricity. Instead, a considerable amount of heat is released into the atmosphere as a byproduct of the generation process, and the resultant energy efficiency is typically no greater than 40%. In other words, a relatively low percentage of the fuel consumed is transformed into useful electric energy. In contrast, CHP recycles the waste heat from electric generation transforming this waste heat into useful thermal energy, typically achieving energy efficiency of 70–80% in the process. CHP plants essentially experience double the energy efficiency of standard power plants.
CHP can provide a secure and highly efficient method of generating electricity and heat onsite, and the energy produced can be dedicated to the mission-critical building. An executive summary from Oak Ridge National Laboratory reveals that the current utilization of CHP in the US avoids nearly 2 quadrillion Btus of fuel consumption and 248 million metric tons of carbon dioxide emissions (Combined Heat and Power: Effective Energy Solutions for a Sustainable Future. December 1, 2008, Oak Ridge National Laboratory; pg. 15), when compared to a scenario in which the thermal energy and electricity are produced separately. Additionally, when CHP plants are partially or fully powered by renewable fuels such as biomass, the positive impact on the environment is even more pronounced, due to the reduction in fossil fuel consumption.
CHP systems are generally economic when used for large-scale facilities, and they can play an essential role in the energy management of mission-critical buildings by serving as the primary source of energy. When CHP is part of a facility’s energy infrastructure, the risks associated with brownouts, blackouts, or damage to the poles and wires of the local utility’s electric grid are mitigated. The role of electricity from the local utility can then shift from the primary source of energy to the backup source. Unlike backup diesel-fueled generators, CHP systems are designed to operate continuously and efficiently, and they are increasingly becoming part of the solution for modern energy generation in large buildings and campuses.
District Energy—An Ideal Complement to CHP
As onsite generation is increasingly being recognized as a more reliable energy solution for mission-critical buildings, it is important to also look at other energy solutions that can control costs, increase reliability, and improve environmental performance. One such solution is district energy. With district energy, one or more central energy plants produce thermal energy (for heating and cooling) and distribute this thermal energy through an underground distribution pipe network that is connected to buildings that are relatively nearby. The district energy network delivers hot water or chilled water to the buildings, which is then circulated for heating, ventilation, and air-conditioning purposes. Once the energy has been extracted, the water is then recovered and piped back to the district energy plant for reprocessing.
By aggregating the energy needs of multiple buildings in one area, a district energy system can serve a steady load that can be managed efficiently and reliably, by utilizing industrial-scale machinery designed for multiple fuels and leveraging technologies that may otherwise be cost-prohibitive to a single customer. In a district energy network, buildings share standby and emergency equipment. Further, the professionals that operate the systems work around-the-clock and maintain backup systems. The International District Energy Association (IDEA) reports that district energy systems typically operate at a reliability of “five nines” (99.999%) and explain that it is unaware of a single rolling “heat-out” related to a district energy system (www.districtenergy.org/benefits.htm). This reliability is essential for mission-critical buildings that require continuous heating and cooling.
Aside from the high degree of reliability that district energy delivers, an individual facility connected to a district energy network can avoid the capital costs associated with buying and installing individual boilers and chillers, as well as the costs for hiring staff to maintain the equipment. Another advantage is that by being connected to a district energy network, valuable space that would have otherwise been utilized to house boilers and chillers may be put to more productive use. Furthermore, with district energy displacing onsite boilers and chillers, building managers no longer need to consume fuels or refrigerants onsite, and the sites become safer and more environmentally responsible. Instead, fuel and refrigerants are consumed at the central plants where strict emission controls are enforced and the quality of air at the buildings improves.
Yet another benefit of district energy is fuel flexibility. While owners of boilers and chillers can only consume the fuel that the technology is designed to ingest, a district energy plant can be designed to run on multiple fuel sources, including fossil fuels (natural gas, oil, and coal), renewable fuels (biomass), or cofired fossil and renewable fuels.
Many large urban areas have proven district energy infrastructures that have been in operation for decades. In addition to urban environments, district energy is also an ideal solution for campuses that have a number of buildings to heat and cool, such as universities and hospitals. This proven technology is safe, reliable, and environmentally responsible, and it is a solution worthy of strong consideration for buildings with mission-critical heating and cooling needs.
District Energy and CHP—Working Together for a More Efficient Solution
CHP and district energy are both effective energy solutions, and they are even more efficient when used in concert since they are naturally complementary partners. The central plants of district energy networks are often powered by CHP or “trigeneration” technology (producing heating, cooling, and electricity), which contributes greatly to energy cost control and carbon footprints reduction (reduced volumes of carbon dioxide emissions). The synergies lie in the ability to use excess thermal energy from CHP processes in the district energy loop.
A common aspect of CHP is that, depending on facility load requirements, CHP plants will sometimes produce more thermal energy than is needed in order to meet electricity needs of the facility. Under this circumstance, CHP facilities that are connected to a district energy loop have the opportunity to sell their extra thermal energy to the district energy system and redistribute the power throughout the rest of the network. Not only does this further bolster network reliability and increase energy efficiency, but it also allows building managers to generate incremental revenues.
Operations and Maintenance of Mission-Critical Buildings
It is important for building owners and operators to recognize that energy sourcing is only one component of a comprehensive energy management strategy. Overall building maintenance and the operation of complex systems within a facility are often handled in-house, even though this type of work is not the core business of the facility owner. In-house operations and maintenance teams often lack the expertise to ensure that energy usage is optimized, and that the performance of the equipment under their care is enhanced economically, technically, and environmentally.
Not only does outsourcing operations and maintenance to qualified experts result in operating savings, optimized energy and upgraded equipment performance, it can also mitigate risks by shifting them to the third party who performs the work. Industry leaders in outsourced operations and maintenance are also adept at transferring in-house personnel to their own payroll, which provides the added benefit of continuity of operations personnel combined with the addition of new best practices and expertise.
Looking Towards the Future of Energy Management
It is undeniable that our world’s energy landscape is changing dramatically and quickly. Smart companies recognize the importance of taking innovative approaches to the challenges they face. For mission-critical buildings, there is no room for error when it comes to maintaining the reliability of critical functions, so evaluating multiple options before making a decision is a wise approach.
The US Department of Energy (DOE) recognized the effectiveness of both CHP and district energy when they announced the recent investment through the American Recovery and Reinvestment Act (ARRA) to support energy efficiency improvements in major industrial sectors across the American economy. Under this recovery plan, $156 million is being allocated towards district energy and CHP, as they are proven effective energy solutions that exist today to enhance efficiency, improve environmental quality, promote economic growth, and foster a robust energy infrastructure.
Within the new regulatory and energy market frameworks, a solution like CHP becomes a very savvy choice. With the impending prospect of carbon regulation—regardless of whether it turns out to be a cap-and-trade system or a carbon tax—CHP’s efficiency gains can lower regulatory risks when compared to traditional power generation. Additionally, if renewable fuel sources such as biomass are utilized, there is the potential for creating marketable credits and an additional revenue stream. These additional revenues can further enhance a positive return on investment in CHP.
Climate change has increased the pressure and expectation from regulators, businesses, and the public in general for greater emphasis on environmentally responsible solutions from businesses and local communities. The demand for operational and energy efficiencies requires us to reexamine every link in our supply chains. Simultaneously, mission-critical facilities must continue to operate in a continuous, seamless manner. The good news is that reliability and cost are not always mutually exclusive. Existing solutions such as CHP, district energy, and facility operations and management outsourced to an experienced provider, can all generate material cost savings, enhanced reliability, and a reduced impact on the environment.