Explained: Microgrids
What are microgrids?
A microgrid is a local power network which provides energy to a group of surrounding users. Microgrids are small-scale versions of central grids, with their own power generation, energy storage and network energy distribution. One key advantage of microgrids is their dual functionality; they connect to the grid but can operate without it.
How do microgrids work?
Microgrids provide power to a small group of users via locally produced energy sources, such as solar panels, wind turbines, or hydroelectric plants. When this power is produced, it can be distributed to users or stored – primarily in a battery, but even pumped-hydro storage. The system which manages the distribution of power is also capable of continuously managing the generation of energy during the peaks and troughs of demand – a feature known as ‘power smoothing’.
The microgrid connects to the central grid via a single connection point which acts as a switch. When the switch is ‘open’, the microgrid can maintain the same voltage as the central grid and therefore integrate as part of the wider power network. The connection is bidirectional which means the microgrid can both transmit and receive power from the central grid.
When ‘closed’ the grid becomes an ‘island’ which operates as a normal closed network. Since microgrids often incorporate renewable energy sources which suffer from issues of intermittency, they also will need a back-up source (such as a power generator) if they are to be truly self-sufficient. You can read more about the intermittency issue here.
What are the benefits of microgrids?
Microgrids are essential in the drive for a low carbon economy. By connecting local power sources to the wider network, they are an integral part of moving reliance away from large-scale fossil fuel-based power sources to smaller renewable sources. Distributed networks are also much more efficient since they can manage energy production according to demand on a more local basis and with a greater degree of accuracy. It also means that far less energy is lost in transmission, which in central grids where energy sometimes must be transported long distances can be up to 25%.
Microgrids can also supplement the existing central network, providing “grid services” to store energy when it is cheap (in off-peak times) or provide energy when it is expensive – a feature of the bidirectional connection point. They can also serve as backup capacity or can even assist with smoothing out frequency and voltage fluctuations.
Microgrids provide their users with greater certainty of energy supply and control over their energy costs. They can be incredibly helpful where network reliability is lacking or subject to interruption in more remote regions. Even where the central grid power is generally more reliable, microgrids can provide certainty to energy users where even occasional power-shortages can be costly or dangerous – for example manufacturing plants or hospitals. Further, a localised power network also offers insulation from external events such as extreme weather conditions or man-made events like or cyber-attacks. With both threats on the rise across the globe, moving to ‘modular’ power grids will be key to minimising the damage caused and enabling an effective response.
What are the potential applications of microgrids?
Currently, microgrids are generally only used by large organisations such as hospitals, manufacturing facilities or universities. However, as discussed above they have a huge amount of potential and are already being applied in exciting new ways. For example, a winery in California called Stone Edge Farm has developed a comprehensive microgrid which incorporates various renewable energy sources and methods of storage. The farm uses the microgrid as part of its wider sustainable strategy since it also grows its own foods and has a sophisticated water management system. Along with the microgrid, these have enabled the vineyard to achieve a carbon-negative footprint - providing an incredible (albeit expensive) example of what can be achieved with the right approach.
Once widespread, microgrids could also help to change energy usage habits through a concept known as ‘collective self-consumption’, which is where producers and consumers form local collectives to manage their energy needs. For example, a solar panel owner that produces excess power could form a cooperative with their neighbours to supply them with energy at a given rate. By joining together, different parties can pool their resources and potentially gain access to technologies that would otherwise be unavailable – due to cost, not having the space for the installation, etc. This also taps into the fact that buildings will be their own power stations in the future.
Co-ops do present significant logistical, technical, and financial challenges. Fortunately, there are many technologies in the microgrid space on the rise. For example, Green Energy Corp in the US are helping to simplify the process of developing a microgrid by providing ‘Microgrid as a Service’ – they offer both project development services as well as ongoing technical support. Another start-up called Fohat (based in Brazil) is developing a software platform which integrates distributed energy sources and manages peer-to-peer trading through blockchain technology, providing transparency and enabling users to choose from a variety of suppliers.
With all the technical challenges, there is clearly a long way to go before we see microgrids on a widespread scale. However, their contribution to the energy puzzle is clear: relieving demand from the central grid and providing local, reliable, resilient energy to surrounding communities.
Author: Thomas Parke