Microgrids

Types of Microgrid

Microgrids are built and deployed for a variety of reasons. They can be grouped into roughly five categories.

  1. Community Microgrids (focus of this article) – are microgrids designed to service a designated community. They may or may not have a connection to the main grid. The focus of this type of microgrid is to pool local resources (mainly small-scale renewables) to maximise energy self-reliance. They may also be built or joined for financial reasons – such as high electricity prices on the main grid.

  2. Campus and institutional microgrids – are for places such as universities and hospitals that need to maintain a power supply in the event that the main grid goes down. The main purpose of this type of microgrid is to maximise usage of on-site generation.

  3. Remote area microgrids – have no connection to a larger grid, and must be completely self-reliant for their energy needs. The purpose of this type of microgrid is to provide constant, reliable power for the community it serves. Examples include microgrids for remote mining settlements or small to medium-sized islands.

  4. Military base microgrids – maintain a connection to a main grid but also have enough generation on site to power the community they service for as long as possible in the case of a mains grid outage.

  5. Commercial & industrial microgrids – are for commercial, manufacturing or data storage facilities for which loss of power supply could be devastating or costly. In these cases, the purpose of the microgrid is usually to maintain supply for at least long enough to power down without damage to the system, but in some cases they may be able to supply power to the system indefinitely.

Components of a Microgrid

  • Local generation - Any type of generator may have a place on a microgrid, but the ‘fuel free’ nature of renewable energy sources makes them particularly appealing for two main reasons: 1) lessened need to import fuels, and 2) decreased exposure to fuel price fluctuations. Solar PV panels, wind turbines, waste-to-energy, biomass and small-scale hydro power plants may all feed into a microgrid, but diesel generators and cogeneration facilities may also be deployed as backup or to maximise resilience.

  • Consumption (AKA ‘load’) -  There is no point in having power generation if there is no one available to use it. Any type of building or structure that uses electricity is considered a load, and taken into account in the demand-supply energy balance.

  • Energy storage - A higher reliance on affordable but ‘intermittent’ renewable energy generators like solar panels and wind turbines lends to various forms of energy storage – with electrical battery storage (e.g. batteries) being the most versatile and (increasingly) affordable. Energy storage will enable the microgrid to store excess energy in times of surplus and release it again in times of need.

  • Grid management system: A microgrid taking advantage of modern communications technology will have a ‘smart’ system in place that puts all resources to use in the most cost-effective and efficient way possible. When electricity demand looks ready to outstrip supply, the management system may even ‘shed’ optional loads – remotely and automatically switching off non-essential devices within households and other buildings to prevent a blackout.

  • Point of common coupling (PCC): This is the point at which the microgrid connects to the mains grid. A PCC is not a feature in all microgrids, but where it is it offers an extra degree of resilience, as the mains grid can be drawn on as a source of ‘backup ‘power’. Conversely, in the event of a mains grid outage, the microgrid may be able to continue to operate normally.

Joining a Community Microgrid

If you are interested in joining a community microgrid, you have one of the three options below.

  1. Finding an existing microgrid to become part of - Unless there is an up-and-running microgrid nearby that is willing to bring you into their fold with a new physical connection to your home, this will require physically moving house. You could start by searching for community microgrids near you, but at this stage there are relatively few available.

  2. Creating a microgrid out of existing network infrastructure - Depending where you are and what the situation is with your local electricity network company, you may be able to pool resources with your neighbours, community or local government to ‘detach’ from the main grid. Substantial planning would need to go into this approach, and the costs will involve both buying out the existing infrastructure from the entity that owns it as well as ensuring that there is enough energy generation and storage capacity located on your grid node to sustain your community without a connection to the larger grid. Some kind of management system will also be necessary to ensure that all the local resources are put to the best use possible.

  3. Creating a microgrid from scratch - This is potentially the most capital and planning-intensive option of the the three detailed here, especially if the goal of the microgrid is to take an entire community off the grid. In addition to the considerations in item 2) above, it will also be necessary to build the connection infrastructure itself – the ‘poles and wires’ of the system. This option may be best for communities where each individual  home is already energy independent on its own right, as building a microgrid would mainly be a matter of ‘connecting the dots’ to tie the collective capacity together.

In Summary

Community microgrids are one of the most exciting concepts to have to have emerged in the distributed/renewable energy revolution. They present a unique, appealing, and (possibly) economical option for communities to take their energy matters into their own hands.

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