A grid is an electricity network that connects consumers (homes, business establishments, and industries), infrastructure (wires and poles), and power plants. It can be divided by scale into macro and microgrids, and both can be owned by the government or a private group. Grids generally operate by producing energy using gas generators, which are then distributed to a wider area using transmission lines. Someone who is connected to the macrogrid can send or consume energy directly to/from the grid, and microgrids operate on this same principle. Microgrids are localized versions of the grid system that can operate on their own or in tandem with a macrogrid. Because of their size, they have a more limited range and can power at most a small city. Despite this, the unreliable nature of macrogrids through power outages and energy insecurity can lead one to choose to be connected to a community microgrid rather than a standard macrogrid. In this way, a solid, local system provides a building with a reliable power supply generated from renewables such as wind, geothermal, hydropower, or solar energy in tandem with gas generators.
Microgrids essentially perform like macrogrids but are tailored to the needs of a specific area. They can range in size from 100 kilowatts to multiple megawatts, which enables them to power anything from a single building to an entire community. From a technical standpoint, they are constructed similarly to the macrogrid but with greater emphasis on renewable energy and storage. Microgrids do commonly contain natural gas generators, but in tandem with renewables such as solar, wind, and hydropower. Therein lies another of a microgrid’s strengths – the energy production capabilities of these sources are catered to the requirements of the area it will be supplying, and a microgrid manager controls this output depending on the load. In being able to reduce energy production and transmission when necessary, microgrids reduce greenhouse gas emissions at the source by only producing the required energy load for the city and with more carbon-neutral energy sources. Alternatively, a microgrid controller can focus on profits by selling excess energy to third parties for credit. Generally, microgrids are connected to the macrogrid and serve as a failsafe if the macrogrid suffers an outage, as demonstrated in some of the case studies included in this report.
Microgrids can come in different forms, including general-purpose and community-focused. These impact the energy production of the microgrids by powering different things- general-purpose microgrids provide energy much like the macrogrid where needed, while a community microgrid serves a more public focus, powering emergency services, cell towers, and water pumping. For residents of Easton, a general-purpose microgrid would better address emissions issues because it would focus on residential infrastructure and replace the entirety of the energy currently being consumed from the macrogrid, which primarily consists of fossil fuels. Whether 100% on renewable sources or not, powering a community with a microgrid makes great strides toward reducing emissions and increasing grid resilience. As such, microgrids have been found to garner more community involvement in the process because communities can limit the impact of costly power outages and support the continuity of service at affordable costs. Furthermore, in being tailored to the energy needs of a city’s residents, the community would have the opportunity to learn about their energy consumption, and why this is relevant to the health of the community and the climate.
Microgrids can also mitigate energy losses by reducing transmission distance and thus line losses. Since microgrid electricity is produced locally, line losses are minimized and there is less power required to meet general demand. Additionally, the locality of the microgrid can allow for the heat produced during energy production to be captured and repurposed for other energy needs. which could be beneficial to the lower-income renters of Easton that use more heat on account of their poorly constructed and maintained homes and apartments.
Because of current financing structures, a microgrid would only be able to power publicly-owned residential infrastructure, which limits our implementation areas. Many microgrids across the nation use solar energy as a renewable power source as it only requires access to sunlight to function. Using solar as the power source for a microgrid aligns with goals set in EP-2 of Easton’s climate action plan, as they seek to expand and support solar installations on new projects. While renewable energy production is generally focused on solar, Easton’s geography as bordered by the Delaware River could also allow for a unique integration of hydroelectric power. An Easton resolution has determined that hydropower along the canal system could be a feasible source of renewable energy for the city and is working with New England Hydropower LLC to develop these facilities, so this could be a significant aspect of the renewable energy portfolio of an Easton microgrid, but more research is needed. The amount of energy generated is also important, as it must reliably support the buildings that we have chosen.
This is one of the most significant challenges faced by MIT and the Masdar Institute- determining the components that will enable sufficient power generation for the needs of the community. Naturally, finding the optimal ratio for cost vs. emissions is difficult as the two are contradictory, but systems and techniques were developed to assist in this decision. The Masdar Institute has developed an “analytical tool to help designers create the best possible microgrids for their needs, given the relative importance they place on minimizing emissions versus minimizing cost… For a defined level of demand and reliability of service, this powerful tool can determine the mix of devices and the strategy for operating them that will best meet the needs and preferences of the designer.” One aspect of this analysis of particular importance is the Pareto front, which graphs emissions and costs to demonstrate the best possible solutions in any combination of design and operating choices. While this tool could be an integral part of establishing a microgrid within Easton, we must first determine the balance of emissions and costs that is acceptable for Easton and perform more research into the energy demands of the city. It should be noted that in performing these emission/cost analyses, one must include the emissions created during the manufacturing and installation of these technologies to produce the most accurate analysis.
In summation, microgrids generally consist of renewable energy sources such as turbines and solar panels alongside generators to produce the necessary energy for a given area. They are flexible in that they can be catered to the energy needs of any area, and their employment of renewable energy reduces greenhouse gas emissions. In addition to using more renewable energy, the locality of the grid makes use of energy that would otherwise be lost when traveling from a centralized power station, known as “line losses.” It would also enhance grid resilience during extreme weather conditions as its relatively small service area is significantly less susceptible to damages, preventing further energy-intensive blackouts. These benefits are emphasized by the real-world case studies where microgrids have been implemented.
Microgrids are being implemented in cities across the country to deal with various energy-related issues, and with notable benefits in many areas. In addition to playing an essential role in removing planet-warming emissions from utilities, the advancement of microgrids can also assist in providing climate resilience to frontline or marginalized communities. This is of particular importance because these people are often the most impacted by climate change. Because of this, many communities view microgrids as a key solution to building climate resilience. Two such Boston communities that are attempting to establish microgrids are Chinatown and Chelsea, each of which is heavily burdened by climate change.
Following the efforts in Chinatown and Chelsea, neighborhoods, cities, and community groups, such as Roxbury and Cambridge, have expressed significant interest in microgrids themselves. This expansion of microgrids lays the foundation for enabling residents to take control of their energy and creating communities that identify as climate-resilient, an issue that low-income residents in Easton need to improve their energy efficiency. Below are a few brief descriptions of case studies where the benefits of a microgrid were realized in other ways.
Case Studies:
Chelsea, Massachusetts
Chelsea, Massachusetts is another such city that is designing a microgrid with a specific focus on the compromise between city officials and the community. This “microgrid without borders” is designed to power a couple of critical buildings, and then as many citizens as can be supported by the remaining power. As a small industrial city located near Boston, Chelsea is only 2.2 square miles, causing it to be one of the state’s most dense populations. Although the city has numerous reasons for wanting a microgrid, the main one is Hurricane Mario in Puerto Rico. The storm decimated the vast majority of the island’s grid in 2017, which created the largest blackout in United States history. This felt incredibly close to home for many of Chelsea’s residents, as the community has an exceptionally large Puerto Rican population. One of the main reasons why the microgrid in Chelsea is so successful is due to how small the town is. The microgrid is located right in the center of the city, allowing it to power numerous significant buildings. Another reason why it succeeded is that the project was centered around the existing community, which isn’t normally the case. One of the biggest pullbacks for why microgrids are difficult to implement is the immense cost. Luckily the project received a $200,000 grant from a nonprofit organization called Green Communities. This not only allowed them to build the microgrid but also helped the city strive to decrease its carbon emissions and save money on energy. This is yet another example of the flexibility of microgrids and the benefits that they can bring to a community.
Bronzeville, Illinois
Bronzeville, Illinois is another unique case of microgrids in which a community microgrid is connected to another at the Illinois Institute of Technology, creating a microgrid cluster that increases efficiency and reliability. This cluster will allow the city of Bronzeville and the University of Illinois to share power in the case of an outage. Additionally, the microgrid cluster allows either party to cut back on its nonessential loads and share power with the other, which is a huge deal in today’s power world. The Bronzeville microgrid consists of 750 kW of PV, a 500 kW/2 MWh battery energy storage system, and a 5 MW of dispatchable natural gas generation. Essentially, this means that the microgrid cluster could keep both the city and the university powered for up to four hours. The Bronzeville microgrid project will be completed sometime this year and will be located just south of Chicago. It is incredibly difficult to find the proper funding for a project of this magnitude, which is why the $4,000,000 grant from the DOE’s Solar Energy Technologies Office was such an immense help. The microgrid will save the Illinois Institute of Technology a whopping $200,000-$1,000,000 per year, so they should have a phenomenal return on their investment in no time. This efficiency and reliability are why the Bronzeville microgrid should be a model for other microgrids around the country and even the world. Additionally, it is why Hamden, Connecticut is planning to build one microgrid by 2025 and another by 2030, to provide power to the 62,000-person town as well as its schools, shopping centers, emergency services, and town center.
Princeton University
Princeton University’s campus microgrid is an example of a smaller-scaled microgrid that has proven to be beneficial to the school. The microgrid draws electricity from a gas-turbine generator and solar panel field and can work alongside the existing utility grid or be completely disconnected when energy from the utility grid is threatened. This specific microgrid is capable of producing 15 megawatts of energy. Normally, Princeton’s microgrid operates while synchronized with the local utility, which benefits both the university and local ratepayers. In the case where the price of utility power is lower than Princeton’s cost to generate it, the microgrid automatically transitions to draw from the utility grid. When Princeton’s microgrid produces power less expensively, it will only run in the university’s most highly demanded areas. On the other hand, when Princeton’s microgrid generates more energy than the university needs at a given time, or when the utility grid’s price of power is high, Princeton exports some of this power to earn revenue while also lowering the average power price for grid participants. The microgrid has proven to be reliable after the power outages caused by Hurricane Sandy, as it provided the school with access to electricity after only 20 minutes of no power. In addition, this microgrid on Princeton’s campus allows them to have a much lower carbon footprint and higher reliability associated with behind-the-meter CHP. In addition, Princeton’s microgrid offers itself as an example of what it takes to build a successful microgrid. This includes economic dispatch, underground power distribution, full commissioning and periodic resetting of critical components, testing using realistic conditions, designing systems with multiple fuel and water supply options, regularly practicing the use of emergency response teams, and planning for human needs during regional emergencies.
Blue Lake Rancheria, California
Located in California, the Blue Lake Rancheria Tribe invested in the implementation of a microgrid for their hotel, casino, and Tribal buildings with hopes of increasing their power reliability and resiliency. With the ability to control their energy source, the microgrid saves them over $200,000/year in energy costs and cuts 200 tons of GHG/year. This allows the microgrid to serve about 10,000 people (or about 10% of the country’s population) in an outage. The implementation of this microgrid shines a light on how badly resources are needed during an extended power outage. Even excluding the power shortages, the Blue Lake Rancheria microgrid served as an example of how all microgrids should be. The project received a Microgrid Greater Good Award from Microgrid Knowledge at Microgrid 2019 in San Diego. It was selected due to both its environmental and economic benefits. Microgrids are incredibly expensive to implement, which is why the $5,000,000 grant from the California Energy Commission’s Electric Program Investment Charge was so beneficial.
Colleges are establishing microgrid systems as well, such as Las Positas College in California. Their project began by determining the project needs, the goals of the microgrid and the power demand of the College to frame the issue and advance with the details of energy-producing technologies and the necessary storage for a reliable system. Upon the implementation of this microgrid, Las Positas College demonstrated a potential 10-12 year financial payback, operational benefits to the college, and social and environmental benefits. The projected savings from the microgrid were $100,000 to $150,000 per year, which represents a similar cost/benefit ratio to that of installing PV cells.