There are several discussions out there about off-grid electricity; but how they actually microgrids work? Explained briefly by Allison Lantero from the Department of Energy and the Microgrid Institute.
What is a microgrid?
A microgrid is a local energy grid with control capability, which means it can disconnect from the traditional grid and operate autonomously.
How does a microgrid work?
To understand how a microgrid works, you first have to understand how the grid works.
The grid connects homes, businesses and other buildings to central power sources, which allow us to use appliances, heating/cooling systems and electronics. But this interconnectedness means that when part of the grid needs to be repaired, everyone is affected.
This is where a microgrid can help. A microgrid generally operates while connected to the grid, but importantly, it can break off and operate on its own using local energy generation in times of crisis like storms or power outages, or for other reasons.
A microgrid can be powered by distributed generators, batteries, and/or renewable resources like solar panels. Depending on how it’s fueled and how its requirements are managed, a microgrid might run indefinitely.
How does a microgrid connect to the grid?
A microgrid connects to the grid at a point of common coupling that maintains voltage at the same level as the main grid unless there is some sort of problem on the grid or other reason to disconnect. A switch can separate the microgrid from the main grid automatically or manually, and it then functions as an island.
Why would a community choose to connect to microgrids?
A microgrid not only provides backup for the grid in case of emergencies, but can also be used to cut costs, or connect to a local resource that is too small or unreliable for traditional grid use. A microgrid allows communities to be more energy independent and, in some cases, more environmentally friendly.
How much can a microgrid power?
A microgrid comes in a variety of designs and sizes. A microgrid can power a single facility like the Santa Rita Jail microgrid in Dublin, California. Or a microgrid can power a larger area. For example, in Fort Collins, Colorado, a microgrid is part of a larger goal to create an entire district that produces the same amount of energy it consumes.
Other examples of microgrids around the world are available on Berkeley Lab’s example page.
MICROGRID TRENDS
The number of installed microgrids is small, but it’s growing in many regions around the world. The International Energy Agency (IEA) estimates that to achieve its goal of universal access to electricity, “70% of the rural areas that currently lack access will need to be connected using mini-grid or off-grid solutions.”
Microgrid projects are driven by factors that can be very different from one deployment to another. Some key drivers include:
- Need for electrification in remote locations and developing countries
- Customer need for more reliable, resilient, and sustainable service
- Grid security and survivability concerns
- Utility needs for grid optimization, investment deferral, congestion relief, and ancillary services
- Demand for lower-cost energy supplies than are locally available (especially at remote sites, such as islands, military or mineral/resource installations, and isolated communities relying on expensive, high-polluting fuels)
- Environmental, efficiency, and renewable energy benefits
In many areas, however, microgrids face challenges and uncertainties across a range of issues — including:
- Government policy, regulation,
- Utility tariffs, contracting,
- Financing, risk management
- Interconnection, interoperability
- Resource planning,
System operations - Technology and
- Fuel supply trends
DERs and technologies available to make microgrids work:
- Microgrid control system
- Energy management systems
- Gas or diesel cogeneration / CHP
- Fuel cells and microturbines
- Photovoltaic (PV) modules
- Wind, biomass, small hydro
- Storage capacity (usually batteries)
Fully grid-tied systems that can’t operate in island mode aren’t microgrids, but instead are defined as grid-tied distributed generation (DG). Also, backup systems that serve very specific, limited loads and don’t otherwise actively balance supply and demand, might be considered microgrids, but arguably they are more properly in the categories of uninterruptible power supply and simple backup systems.
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