What is a Microgrid?
What is a Microgrid?
The Department of Energy (DOE) defines a microgrid as “a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can operate in either grid-connected or in island mode, including entirely off-grid applications.”
This means that if a facility has energy needs (load) and produces energy (distributed energy resources), in such a way that it can connect to the larger energy grid or operate while cut off from the grid, then it is a microgrid.
One common type of microgrid is a solar array with battery storage at a facility, which allows the facility to stay partially or wholly powered during a blackout – but there are many other possible types of microgrids.
Why a Microgrid?
Microgrids can provide many benefits to a facility and to the surrounding area. Microgrids increase a facility’s energy reliability and resiliency, provide economic benefits, increase energy independence, and decrease environmental pollutants like greenhouse gases.
Reliability & Resiliency
Energy systems that are reliable and resilient are capable of consistently serving energy needs even in the face of instability, reducing or even eliminating interruptions like blackouts. Microgrids can provide a facility a consistent source of energy that is produced on-site which reduces vulnerability to outages and shortages of the larger electric grid system, including cutting out the need to import fuel for backup generators and other supply chain vulnerabilities. As a microgrid is designed for the specific site and facility, it can be tailored to withstand local hazards while meeting a facility’s needs.
Energy systems that are reliable and resilient are capable of consistently serving energy needs even in the face of instability, reducing or even eliminating interruptions like blackouts. Microgrids can provide a facility a consistent source of energy that is produced on-site which reduces vulnerability to outages and shortages of the larger electric grid system, including cutting out the need to import fuel for backup generators and other supply chain vulnerabilities. As a microgrid is designed for the specific site and facility, it can be tailored to withstand local hazards while meeting a facility’s needs.
Microgrids can provide on-site power for a facility that doesn’t need to be paid for once built. Extra power generated in a microgrid can be sold back to local utilities for energy credits or occasionally monetary deposits. Even if a microgrid does not generate enough energy to sell back, or is only used for emergency situations, the decrease in energy interruptions allows a facility to run without incurring the costs associated with these interruptions.
Microgrids also empower facilities to have more energy choices independent from the wider grid and power producers. Facilities may choose particular energy sources and mixes of sources according to what works best for the facility’s site and what types of energy the facility desires. This includes choosing how dependent on the larger electric grid a facility’s microgrid is. A facility may choose to develop a microgrid that operates as only backup energy in emergencies to a routine addition during normal operations to generation that is used more often than the utility-provided energy.
Microgrid Technologies
Solar energy is commonly used for energy production in microgrids. Solar panels take in energy from the sun’s rays and transform it into electricity that can be used immediately or stored in batteries. Solar arrays generate a predictable amount of electricity with little maintenance and no emissions; and they can be configured in unique shapes and sizes to fit a facility’s site.
Solar arrays are also easy to combine with other electric generation on-site and can even be combined with other uses at sites (such as covering walkways or parking lots).
Some facilities may find it difficult to install solar panels if there’s no available flat (or flattenable) surfaces due limited space or unsuitable buildings. Solar production and available power will also be limited by the size of the array and battery storage.
For more information on solar in PA, see Solar Energy | Department of Environmental Protection | Commonwealth of Pennsylvania
Geothermal energy harnesses the heat energy from the Earth below. Geothermal wells are dug under a facility or nearby on-site, allowing for energy to be produced directly on-site. Wells can be dug to various depths to access various amounts of geothermal energy. Geothermal energy can be developed in very site-specific ways to augment energy production for a microgrid.
While only a few facilities and their sites in Pennsylvania are suitable for using geothermal energy for electric generation, virtually all of Pennsylvania is suitable for using geothermal energy for heating and cooling.
For a quick overview of geothermal energy and its potential in PA, see: Pennsylvania Report - Executive Summary
Wind
Wind power is another form of energy production that generates a predictable amount of electricity without creating emissions. Wind power allows for electric generation throughout the day-night cycle if in the right place.
While wind power is possible in much of PA, the most worthwhile sites for wind are limited to specific parts of Appalachia and the shores of Lake Erie.
Some places have seen limited urban adoption through small vertical wind turbines, which can be fitted into far more circumstances, albeit with smaller production capacity.
For more information on wind in PA, see the wind section in Renewables | Department of Environmental Protection | Commonwealth of Pennsylvania
For more information on where wind is most suited for in PA, see WINDExchange: Wind Energy in Pennsylvania
Hydro
Hydropower has been providing energy for people since long before electricity was harnessed. A micro-hydropower system – hydropower generation of under 100 kw - can provide extra wattage from waterways with consistent flow. Larger on-site hydro projects may also be possible, if a facility’s site has the right conditions.
Hydropower is bound by the specific environment of each site more than other generation types, but understanding if hydropower is a feasible option is possible from the very beginning of planning. Building a hydropower project with a dam or low-head dam (weir) involves navigating robust environmental impact regulations that run-of-the-river hydropower projects do not involve.
For more information, see: Types of Hydropower Plants | Department of Energy
Nuclear
An emerging option for microgrids is nuclear power. There are several small nuclear reactor – or microreactor – designs that have been built, and small modular reactors (SMRs) have also been deployed. Nuclear power is carbon-free and buildable at any site, producing extremely reliable energy in a highly controlled manner.
Nuclear power also comes with many responsibilities and regulations to keep operations safe, and any plans to use nuclear power in a microgrid must include solid plans to operate the nuclear generator correctly.
For more information, see: Microreactor Technology at Idaho National Laboratory Overview - Idaho National Laboratory
Other Options
There are more ways to produce energy on-site, and technology is always advancing to make different modes more feasible. Facility’s looking to produce its own energy is not bound by the options presented above.
Whether it’s looking at the above power sources in different formats, smaller parts of the energy sector like renewable biofuels and biomass, or interest in new power sources, microgrids can be designed from the very beginning with a unique loadout that suits a facility best.
PA Funding Resources
The state of Pennsylvania runs several programs and hosts several tools that can be used to help finance a microgrid or microgrid components. A list has been compiled below:
Commercial Property Assessed Clean Energy (C-PACE): C PACE | Department of Environmental Protection | Commonwealth of Pennsylvania, Pennsylvania C-PACE - Pennsylvania C-PACE, Alternative & Clean Energy Program (ACE) - PA Dept. of Community & Economic Development
DEP Energy Programs Office Funding sources:
- Energy Funding and Assistance Finder
- PEDA
- Green Energy Loan Fund (GELF)
- Municipal Opportunities for Retrofits and Energy Efficiency (MORE) Program
PA Department of Community and Economic Development Programs
PA Microgrid Examples
Regulations
The interconnection between a facility's microgrid and the wider electric grid allows electricity to flow not just to a facility, but from it. It is the interconnection process that allows a facility with a microgrid to sell its excess energy to utilities. Each utility has its own interconnection process that must be followed. As this process can take a long time, it is important to note that the microgrid process itself does not need interconnection, interconnection is only needed to sell electricity to a utility or aggregate bundle. As such, a facility can complete and use a microgrid without an interconnection, the microgrid will just not be able to sell its electricity until it is interconnected.
The Federal Energy Regulatory Commission (FERC), regulates the wholesale sale and interstate transmission of energy. It creates regulations that determine how electricity can be sold, including excess electricity produced by microgrids.
The most important regulation for facilities with microgrids is the newly finalized FERC order no. 2222. FERC 2222 requires transmission organizations to create a way for Distributed Energy Resources (DERs), such as microgrids, to participate in their electricity markets. Under 2222, DERs can be put into aggregate units with other DERs that have their electricity sold on the transmission organization’s market. Pennsylvania’s transmission organization is PJM.
As FERC 2222 is still new, PJM has not yet completed setting up their system for DER aggregates. Facilities with microgrids that are interested in selling excess electricity to the grid at large instead of their individual utility should make sure to check PJM’s official communication channels for updates on the aggregate system.
Most regulations involving microgrids do not come from the federal level, but state, county, or municipal levels. The most important body for microgrids are local zoning boards that will decide whether to permit a microgrid siting, and under what circumstances. In Pennsylvania, zoning boards are functions of municipalities, unless there is no municipal zoning board, in which case the county zoning board serves that capacity. These zoning boards are the AHJs – Authorities Having Jurisdiction – alongside other bodies that may have jurisdiction over aspects besides siting permits.
Siting permits are the primary permits needed to build a microgrid. As a microgrid often involves building energy generation where there wasn’t any before, these permits are usually extremely comprehensive in considering all impacts and environmental risks that may arise. However, despite being a type of energy generation build, microgrids are small, can go in places that are not usually industrially zoned, and do not carry the same risks as a typical large plant. As such, most zoning boards do not have a pre-existing process or procedure for permitting microgrids.
When approaching a zoning board for permits, a facility may have to provide much more information to the board about the technology they intend to install than if they were building a new building or installing an HVAC system. A permit will typically only be granted when the impacts and risks are understood and planned for well enough. For some parts of the microgrid, this may be very easy. A solar array and other types of on-site power generation can involve less risk to the area than a traditional backup gas generator. For other parts of a microgrid, such as batteries for energy storage, permitting may be more complicated. It’s important to understand what concerns the AHJs may have and address them early on in the process so that the microgrid can be developed smoothly.
Battery Energy Storage Systems (BESS), or on-site energy storage, are one of the most difficult parts of a microgrid to permit. In Pennsylvania, AHJs are primarily concerned with fire safety. Some AHJs across the country have also put noise and aesthetic considerations into their permitting regulations.
The biggest concern people have about BESS in Pennsylvania are the fire risks of storing large amounts of electricity in a battery. Like an electric car’s battery catching on fire, a BESS that catches on fire is best left to burn itself out instead of using water or traditional fire suppressants. As such, AHJs may have strict safety standards that must be met to approve any permits. While there is no overarching federal safety regulation for BESS yet, there are some fire safety standards made by independent industry organizations, such as the National Fire Protection Associations standard and UL’s 9540 standard and testing. One of the best ways to ensure a BESS meets a permit’s safety standards is to carefully vet the battery before buying it. Making sure a microgrid’s batteries have a high threshold for thermal runaway, are from a company with high safety standards, and meet the regulations of organizations like UL can significantly decrease risk. AHJs may be unfamiliar the details of batteries and err on the side of caution when it comes to something as serious as fire. It’s important to work with the AHJs, including the local fire departments, to make sure everyone understands what the actual risk of BESS are compared to other fire risks. Permits often require that a fire safety plan be made specifically for a BESS, which should always be adhered to.
Some places across the country have put in permitting ordinances based on aural and aesthetic concerns. In practice, the typical noise level of a BESS is 70-75 dBA – slightly louder than an average conversation, slightly quieter than yelling – and comes primarily from a BESS’s cooling system. A noise study and/or plan to manage noise levels may be part of the permitting process. Some communities are also concerned with aesthetics and may require a specific type of fence or landscaping around a BESS.
BESS are a way to store energy to be used later, often taking a role that would otherwise be filled by traditional petroleum backup generators. Like backup generators, BESS can catch on fire and release chemical fumes that a bonfire would not, although BESS do not carry the additional risk of leaking fuel into the ground that traditional generators do. Like backup generators, the risk of fire significantly decreases when safety and security are considered from installation through maintenance.