The microgrid is a disruptive technology. It can provide reliability, resiliency, and security of supply for the community it serves, whether it is a college campus, a military base, or a neighborhood. It can also benefit the distribution grid. But states and regulatory agencies are struggling with how to integrate microgrids into the utility grid at the same time they see an aging utility grid greatly in need of innovation.
Hurricane Sandy handed Connecticut, New York, and Massachusetts a major wake-up call when the utility grids proved to be so vulnerable to the gale winds. All have established or are working on regulations that will, in the end, promote the building of microgrids to provide dependability and adaptability in the face of climate change.
So what is a microgrid? The US Department of Energy defines it as “a group of interconnected loads and distributed energy resources with clearly defined electrical boundaries that act as a single controllable entity with respect to the grid. [A microgrid can] connect and disconnect from the grid to enable it to operate in both grid connected or island mode.”
Connecticut has enacted several regulations pertaining to microgrids, identifying them as distributed generation: the first regulation enables utilities to own distributed generation, the second enables the distribution of power from distributed generators to multiple users, and the third establishes a microgrid grant and loan program.
In July 2013, Connecticut’s Department of Energy and Environmental Protection awarded nine grants to cities around the state under a first round of awards for microgrid projects. The purpose of the grants, according to Connecticut Governor Dannel P. Malloy in a March 6 statement, is to help cities minimize hardships to residents and businesses during severe storms that shut down utility electrical grids. Proposals for a second round of grants were being accepted in April 2014.
The projects are intended to provide power for government services and businesses that are critical during extreme weather events; these include police, fire, emergency response operations, and hospitals.
In briefs submitted to Connecticut’s Department of Energy and Environmental Protection in December 2012, Connecticut Light and Power and United Illuminating discussed issues they face in complying with the regulations the state enacted, in particular concerning the distribution of power to multiple users organized in microgrids. Various state and federal statutes that govern submetering, electricity resale, and other topics must be clarified to allow multiple users to connect to a microgrid, they argued.
New York looks on microgrids quite favorably. Consolidated Edison, for example, has a “”˜utility of the future’ team that is looking closely at technology advancements, efficiency, changing customer needs, information technology, storm response, clean energy, microgrids, and economic recovery,” says Margarett Jolly, director of research and development at the utility, as quoted in a late April issue of Smart Grid Today.
Jolly says “Reforming the Energy Vision” was introduced at a meeting of the New York State Public Service Commission on April 29, a proceeding that will change the vision of the way the grid is designed now to allow the creation of energy resources for which customers can be responsible.
The current grid is inefficient because power needed for the hottest days of the year has to be available year round. Jolly says to think of the grid as becoming a platform for energy to flow in both directions and for producers and developers to provide that energy. This will make the grid more efficient.
“We need to explore different business models and to be open to all markets,” says Jolly. On the one hand, experience, barebones safety, and reliability argue for utilities to own microgrids. However, on the business side, if there are markets and innovations we should be open to them, she says. Ownership of a microgrid and its operations could be separated, she says, implying partnerships between developers and the utility.
More and more ConEd customers are looking to disconnect from the utility grid and operate in island mode and this adds to grid resiliency, she says. And options for cogeneration have improved, she says. Before Hurricane Sandy, the value of islanding was unclear. Now that value can be calculated, she argues.
The Massachusetts Department of Energy Resources (DOER) has initiated a “Community Clean Energy Resiliency Initiative,” as part of Governor Deval Patrick’s climate change preparedness effort. The initiative is designed to fund projects proposed by cities and towns throughout the state that will make them more resilient in the face of catastrophes such as Hurricane Sandy, and tornados. The funding pot is $40 million.
DOER Commissioner Mark Sylvia says members of his staff have been articulating the administration’s position on improving the resiliency of utility grids and microgrids and deploying electric vehicles. Furthermore, the Massachusetts Department of Public Utilities has in its docket a grid modernization plan, but it won’t impact this funding program, Sylvia says.
He adds that the emphasis will be on clean energy. The program offers a great opportunity to explore technologies, especially microgrids utilizing cogeneration and fuel cells, and the ability to island buildings in the face of storms.
The idea is to focus on critical infrastructure that serves the largest populations, Sylvia says. Public/private partnerships are being encouraged, such as hospitals working with regional quasi-governmental agencies. “We would also encourage municipalities to join with other municipalities and apply as regional entities,” he says.
DOER is looking to fund proposals from cities and towns seeking technical assistance, or those that have shovel-ready projects for clean energy technologies. These can include distributed renewable energy projects, energy storage and microgrids, that, in the face of a storm and utility grid shutdown, will island them from the utility grid. The selection process began in May 2014.
DOER hired the Cadmus Group and two subcontractors, MCFA (Mitsubishi Caterpillar Forklift America) and Homer Energy, to assist the department and provide technical assistance to cities and towns who will eventually be awarded funding.
Commissioner Sylvia says the department anticipates awarding a second tranche of funds to the cities who have already received technical assistance and have moved on to begin construction.
In California, the Public Utilities Commission released a white paper that summarizes the microgrid’s current state of development. It covers, in great depth, the issues hinted at in the Connecticut utilities’ briefs. Rather than summarizing its richness of detail, the reader is referred to the CPUC’s website, to read “Microgrids: A regulatory Perspective.”
The Business Perspective
Guy Warner, CEO of Pareto Energy, has identified a niche for microgrids in the market place. Pareto Energy LTD has designed and built microgrids and is now marketing GridLink, a way to integrate new distributed generation capacity with legacy grid infrastructure.
Pareto Energy was founded in 2004 to design and own microgrid systems through power purchase agreements (PPAs). However, the company found it difficult to attract customers because microgrid technology was too new and customers didn’t understand it, Warner says. So, it changed its business model to market GridLink, a non-synchronous microgrid interconnection system.
Warner summarizes where the microgrid industry is at the moment: “We still don’t have a standard way to connect to a utility network that is affordable and quick, and we are trying to find a win-win strategy for utilities to own microgrids,” he says.
He notes that utilities are finding some solutions. “Even when utilities are aligned, customers still need to be educated.” Demonstration projects are needed.
Furthermore, he says, “There is no regulatory construct in which multiple users can share electricity.”
In other words, a group of businesses in a business park would have difficulty forming a microgrid because of regulatory issues surrounding submetering multiple customers and resale of electricity when a utility is providing backup power to the microgrid.
Warner describes GridLink as a non-synchronous link that serves as a back-to-back inverter. Both incoming grid power and microgrid generated power is converted to direct current in an “E House” and then converted back to alternating electricity to be used in the host’s facility. The system has been approved by Connecticut Light and Power, he says.
GridLink was designed to allow the microgrid to automatically continue to operate when the utility grid goes dark. Under black start conditions, without an inverter, the microgrid has to shut down with the grid, and then it is started up to provide electricity to the buildings on its own. Warner says GridLink can also supply ancillary services such as dynamic VAR (Volt Amps Reactance), power factor correction, voltage support, and frequency regulation to help stabilize their local grid and remove inefficiencies.
He says GridLink is being installed for the first time at a shopping center in New York City to interconnect a cogeneration system that had not been connected to the grid. The cogeneration system operated during Hurricane Sandy, and the interconnection will allow cogeneration power to be shared at other nearby sites when the utility grid is offline.
San Diego Gas & Electric (SDG&E) created a microgrid in the desert community of Borrego Springs with funding from the US Department of Energy and the California Energy Commission. The community is located in the middle of a state park surrounded by mountains and is beset with flash floods during monsoon season. Since it is at the end of a 69-kV transmission line the flooding often cuts off electricity service for hours at a time.
SDG&E installed generators and energy storage systems and, in a September 2013 flood, brought power back on to a portion of the town, in essence islanding the community from the grid. SDG&E is continuing to upgrade the technologies and is planning to charge the energy storage batteries with solar power.
The University of California, San Diego (UCSD) has steadily built up its microgrid over the past 14 years, to where it now provides 92% of the campus’s electricity and 95% of the heating and cooling on an annual basis, according to Byron Washom, director of strategic energy initiatives.
The microgrid is made up of two combined cycle gas turbines providing 27 MW, 3 MW of steam turbines, 2.8 MW of fuel cells, 2 MW of photovoltaic solar cells, and 3.8 MW of thermal energy storage. As backup, the plant has a mix of 62 Caterpillar and Cummings diesel generators.
Washom says the acquisitions began with the steam turbines and the thermal energy storage in 200001, and were soon joined by the combined-cycle gas turbines in 2002. The solar PV systems were added beginning with 1 MW in 2007, and now totaling 2 MW.
“We’ve now saturated all architecturally suitable campus roof tops with solar,” he says.
The 2.8-MW fuel cell system, manufactured by FuelCell Energy, began operating in January 2012. Its gas fuel is generated by methane from the Pt. Loma wastewater treatment plant 17 miles away. The wastewater plant injects the methane into a San Diego Gas & Electric pipeline, and UCSD receives renewable credits. Washom says the fuel cell plant, which is the largest commercially available fuel cell unit in the world, is working well and supplies 10% of the campus electrical base load.
A 2.5-MW energy storage system is scheduled to be installed by December 2014. Negotiations for a supplier have concluded, but the company name could not be revealed at this writing since the winner has not been publicly announced, Washom says. He emphasizes this is not a demonstration. “It is an early commercial system, and we want to illustrate the flexibility of different solar electricity strategies.”
“We want to be a major participant in the advancement of energy storage in the supply/demand equation,” says Washom. He explains how the energy storage system will be used to shift loads: The energy storage batteries can be charged at night, and discharge the stored electricity during the day to offset electrical imports.
With the growth of renewables in the state, the utilities and the California Independent System Operator are assuming there will be an excess of renewable generation some days. Washom says they will be sending out dynamic market price signals of oversupply, and “we will load up our energy storage system with the power supply.”
He continues, “Based on solar forecasting, we will determine when and how we store the solar generated electricity. If there is a deficit of solar, we will discharge.”
He cites the following example. At 8 a.m. when the plant normally starts to import power, if a high-solar day is forecasted, “we will discharge stored electricity for two hours, and once the energy storage system is fully discharged, we will be ready to store the large supply of imported solar power.”
Washom’s department has also developed an aggressive energy efficiency program. “For the last six years, our budget has been $22 million a year. The strategy has been to meet new energy demand through energy efficiency investments to reduce the energy being consumed by older buildings.”
In the beginning they worked on the low-hanging fruit like lighting, and now they are working on more sophisticated savings, like optimizing air-circulating fans in laboratories-he calls those that aren’t efficient “energy vampires.”
In the last 10 years, UCSD has added 6 million square feet of buildings. The demand is twice that of commercial office space, he says.
As for the future of microgrids in California, Washom pointed out that the two largest markets for microgrids are university campuses and the military, which has six installations in the state. And all have an interest in or are developing microgrids. This is a reflection of both national and international trends, he says.
Two Microgrids Designed for Resiliency
Wesleyan University will not suffer blackouts in the major storms that are likely to hit Connecticut in the coming years. The university is now capable of powering its whole campus-all 81 buildings covering 2.3 million square feet.
Normally, its cogeneration or combined heat and power (CHP) system plus a solar array provide 95% of the electricity the campus uses at all times. In the case of an emergency, by judiciously shutting off lights, some ventilation equipment, and other demand reductions, these can keep the campus operating as a microgrid.
Alan Rubacha, the director of physical plant at Wesleyan, says there are two major reasons that motivated the development of Wesleyan’s microgrid. First, they wanted to reduce their electrical and gas costs, and as they are saving $2 million a year, they achieved their objective. The second reason is reliability. The area had a snowstorm in 2011 that knocked out all the power to the campus. By running the cogeneration plant, they were able to get large parts of the campus up and running.
The system runs parallel with the utility grid under normal operations due to regulations that prevent it from exporting power. Rubacha says, “We have to maintain a little bit of imported power.” But it’s cheaper to use the power on campus instead of exporting it, he adds.
He says a GE Jenbacher 2.398-MW reciprocating engine was installed in 2008 and a Dresser Rand Guascor 656-kW reciprocating engine was installed in 2014. The 200-kW solar photovoltaic (PV) array was installed in 2012. The exhaust heat from the reciprocating engines is used to generate steam for the campus heating system and air conditioning. The heat from the intercooler loop and jacket water is used to heat domestic hot water.
They are keeping their eyes on new technologies as they develop, but that he’s not enamored of fuel cells, says Rubacha. “They are extraordinarily expensive and use the same amount of gas as the reciprocating engines, and don’t make sense for us,” though other facility managers find fuel cells to be desirable because they don’t have to be concerned with the issues raised by mechanical moving parts.
According to Rubacha, Wesleyan paid for the $9.4-million cost of the equipment and installation with a combination of cash and $1.2 million in grants from the state Public Utility Regulatory Authority. Wesleyan was one of the recipients of the grants awarded by the Department of Energy and Environmental Protection in 2013, receiving $600,000 that was used to connect the athletic center’s 600-kW load to the campus grid. It is the first grant-funded project to come online.
The university has plans to expand the microgrid, but it was too early to talk about them, he says. The school is committed to conservation, having already reduced demand by 30% through installing insulation, efficient lighting, and new weather-stripped windows.
Microgrid Designed for Public Shelter
The University of Connecticut was another recipient of a phase one incentive grant from the state. The $2.14 million will be used to convert its 400-kW ClearEdge fuel cell and a 6.6-kW PV solar array into a microgrid. Currently, they provide power to a series of buildings at the Depot, a research campus about a mile from the main campus, according to Rich Miller, director of Environmental Policy at the University of Connecticut.
The underlying motivation for the upgrade to a microgrid has to do with the weather Connecticut has experienced. Miller says the area has had two 100-year storms, a 50-year storm, and a blizzard in the past 3.5 years. Each significant part of the state missed power for extended periods of time, he says. The microgrid is being designed to serve as a storm shelter for the public.
The Center for Clean Energy Engineering and the Center for Energy Innovation, plus other labs and 15 cottages housing learning centers and administrative functions occupy the Depot. It was originally a campus for the handicapped and when it was shut down, the university inherited the buildings, Miller says.
The fuel cell is fed by natural gas and produces no combustion. It, and the solar array, supply 100% of the power needed by the Depot buildings during off-peak hours. During peak hours, the Depot buildings exceed the capacity of the fuel cell and solar array and rely on grid power. The fuel cell’s waste heat also supplies heating and cooling to some of the buildings.
Currently, both the fuel cell and the solar array shut down when the grid goes offline due to a storm or hurricane or other type of accident. They can provide power to a limited number of buildings during the outage. Once the microgrid becomes operational and can “island” the two systems some building loads will still need to be shed since selected buildings will be designated to meet public needs. All of the facilities on the microgrid would experience a spike in demand during a utility grid outage, Miller says.
The Depot will serve as a staging area during outages and the cottages will convert to warming and cooling centers. Utilities and the public will be able to plug in equipment and recharge electronic devices increasing demand beyond the Depot’s normal usage.
The upgrade is still in the design stage. State funding will be released when the project is 30% complete, according to Miller. Schneider Electric has been hired to develop the project, and AC Corporation is the project manager and owner’s representative. All issues concerning the contracts were resolved the first of April. When the proposal was submitted in 2013, the design had to be 60% complete, he says.
The next proposal will likely include energy storage. “The solar system needs a boost in efficiency especially in this part of the country,” says Miller, and energy storage will provide that boost to assure the microgrid is reliable and efficient. He says after the microgrid is operational, there will be darkness for about 1.5 minutes when the grid goes dark. Energy storage will not only fill that gap but also take over when the solar array is not producing power. Energy storage will also offer black start capability to bring the microgrid online when the grid fails.
Battery storage is still being researched for UCONN’s phase two grant proposal, which is due in August, says Miller. They will release a request for proposals from manufacturers before then to get manufacturers’ ideas as to the size and technology of an appropriate system.
Miller says they are planning to expand the solar array with more panels and will likely install other renewable technologies, like wind turbines.
He adds that Connecticut Light and Power has been supportive of the microgrid project and sent its approval of the project in a one-page letter soon after receiving the proposal.A 25-MW cogeneration plant was installed on UCONN’s main campus in 2006, says Miller. It supplies 80% of the campus’s power, and 70% of its heating and cooling needs. It has islanding capability and did so in 2012 during a Halloween snowstorm.