Three ways microgrids can help power resilient communities

Start a conversation about renewable energy and there’s a very real possibility the term microgrids will be mentioned. But here’s where the definition of a microgrid creates confusion, not to mention whether there is a place for decentralised energy in our traditionally centralised energy generation landscape.

A renewable energy microgrid is a system that comprises multiple small-scale energy generation installations connected to the local grid but more importantly to each other, and to storage, and to energy users with a digital architecture to facilitate energy sharing and optimise the supply/demand efficiency. In simple terms, it is power generated and stored locally and distributed and consumed locally at the precinct, neighbourhood, locality or campus scale.

A microgrid is a technology-neutral approach. This means it can incorporate a variety of inputs such as rooftop PV and solar thermal, biofuel generators using local feedstock such as agricultural waste, or small hydropower technology such as pelton wheel turbines in any combination. Provide the appropriate integration platforms and supporting infrastructure including cabling, substations, storage and switchboards – along with energy storage in the form of networked small storage batteries, or a large centrally-located battery – and you have a complete microgrid.

Within a dense urban context, microgrids will typically be grid connected, with some exchange of energy between the microgrid system and the main grid distribution system. But it is also feasible – and sometimes desirable – for the installation to operate in ‘island mode’, that is, without any energy connection to the mains grid.

That is the first big benefit of microgrids – the ability to be energy-independent.

If your conversation is with someone from a remote location, you can bet they’ll have something to say about self-sufficiency. We have been seeing microgrid proposals led by utility companies in regional and rural locations that have aimed to improve energy resilience for “fringe of grid” communities; those who are at the edge of a grid or at the end of a branch of the main distribution system.

This protects community energy supply in the event of grid failure, while also reducing pressure on main grid supply, particularly during peak demand events such as a heatwave. It is also valuable insurance for communities exposed to risks of blackout from storms, flooding, bushfire, or damage to power lines.

The impact of two tornadoes and three damaged transmission lines in parts of South Australia and Victoria provide an interesting case in point. It’s unlikely those at the fringe of the grid blinked an eye. For those in other parts of those states, there was the proverbial jolt – that critical infrastructure can fail and when it does it leaves us without power and feeling powerless.

Currently, much of the investment focus is on utility-scale renewable energy developments. These are typically constructed in regional areas, some considerable distance from the end users. This means there needs to be substantial investment in the enabling infrastructure including transmission wires, power poles, cabling, switchgear, substations and so forth.

But also, as electrical energy is transported over distances, a significant amount of energy is lost from the system. For example, the US Energy Information Agency estimates around 5% of all electricity generated in the US annually is lost during transmission and distribution. That is also why regulators such as the Australian Energy Market Operator incorporate transmission loss factors into the financial analysis of any generation asset’s performance. In essence, the closer an energy source is to the people and assets consuming the energy, the more closely what is generated will match what is available to meet demand.

The other side of this equation is where microgrids are being designed and installed for an existing precinct, community, or campus. Here, the energy use profile can be estimated with a high degree of accuracy before designing and specifying the system. This means assets can be right-sized for likely demand with a margin for contingency and changes such as increased use of cooling as climate change accelerates.

The demand-side factors also form part of the third major benefit of microgrids – they can help progress a smarter approach to energy use.

One of the key elements of making a microgrid successful is ensuring energy users are supported in optimising how and when they use energy, to better match the supply and generation profile of the local renewable technology.

Helping people understand that using the tumble dryer or the dishwasher during the day when solar PV is at peak is better than doing so at night is a good first step. There are also practices such as pre-cooling and pre-warming that can use renewable energy to power the air conditioning or heating and leverage internal materials and spaces as thermal storage which can be explained in user-friendly language.

It is also valuable to have some education and engagement around ensuring essential supplies are maintained if the microgrid needs to switch to island mode. There are ways to use the IoT platforms that manage a microgrid to act as a consumer interface to support good decision-making to protect local supply. This can be tailored to customer needs and overall priorities around what is essential in an emergency such as maintaining power to refrigeration, lighting, communications and basic cooling and ventilation.

While there are demand management approaches that enable the utility manager to remotely switch off householders’ equipment (such as air conditioning during a demand response control event), there are social and ethical issues to consider around who gets to have the power to decide what is most important to people.

Ultimately, how we do energy differently is the core question for the net zero transition as it affects communities and our built environments, infrastructure, manufacturing, and transport. The answer starts with continuing to have conversations that explore options with an open mind and the best interests of stakeholders at heart.