Microgrids - Incorporating Sustainability and Resilience in Power Systems

Do you ever wonder what happens when you turn on a light? Where did that electricity come from? How far did it travel to get to you? What was used to generate it? Most of us don’t know the answer to this which is a pretty daunting thought. It is a commonly accepted fact that humans are contributing to climate change by producing excess amounts of carbon byproduct from our use of fossil fuels. Energy production in the form of electricity is a major proponent of the use of fossil fuels but, as many of us don’t directly interact with this industry, it is hard to understand why this is the case and how we can help to change it. On top of that, power demands are increasing worldwide, and the race for upkeep of our power generation, transmission, and distribution systems (the grid) has become a greater challenge. Most of the operating transmission lines in the U.S. today were built in the 1950’s and 1960’s and were given a 50 year life-expectancy. This means that the vast majority of transmission lines are outdated and have a much greater chance of failing. In addition to operating past life-expectancy, over 640,000 miles of those lines are at full capacity. In the event of an outage, transmission lines often need to be taken down and repaired or replaced which requires that their power load be re-routed through other lines. Since most of these lines are at full capacity this leaves the grid in a vulnerable situation.

It has been seen time and time again how easily a power grid can be taken offline for days, weeks, and even months. This can be due to natural disasters, failing infrastructure, and even cyber attacks. The Ukraine experienced this first hand in December 2015 when Russia led a cyber attack on their power grid effectively gaining access to their control system and shutting down breakers for power distribution. This left 230,000 in the dark for about 2 to 6 days and required manually switching breakers to get the system back up. The control system however, took two months to get back online as the hackers had re-written firmware which made access almost impossible. This is concerning for the U.S. because most of our grid has no manual capabilities and if a cyber attack were to occur there would be no way to restore power without access to the control system.

Natural disasters are another major concern as climate change has been making storms, earthquakes, and fires much more extreme. It has been painfully clear for Puerto Ricans who, after hurricanes Urma and Maria, were left without power for months. Even today, more than 6 months later, over 150,000 homes still have no power. This has been a direct result of an extremely vulnerable power system with single points of failure and no infrastructure set in place as redundancies in the event of this type of disaster. While this may been seen as a worst case scenario, in reality it is a very real possibility for the U.S. and other countries around the world.

 

So how can we change our power systems to be resilient to these types of disasters, failures, and attacks?

Microgrids, or local area power and energy systems (LAPES), are an integrative approach for adding reliability and resistance to a power system without taking it offline. Microgrids are just as they sound - micro-sized grids - and can be implemented anywhere. They utilize a combination of power generation technologies to meet energy demand and can operate in conjunction with the main grid or in ‘island mode’, essentially providing power to only their local area and operating autonomously. A typical microgrid uses photovoltaic panels, fuel cells, batteries, and generators to achieve the availability of power required for undisturbed distribution.

While the term ‘microgrid’ is relatively new, first used in 1997, the use of them can be found as early as the 1880s. All isolated grids are considered microgrids which can be found on large electric ships, remote areas and even the space station. The concept is not new but incorporating these into the main grid certainly is. After the 2011 earthquake in Eastern Japan many of the affected towns decided to increase their resilience by using microgrids. While this was just an afterthought for most towns in the area, there was one microgrid which endured the 2011 earthquake. In Sendai, Japan a campus microgrid provided power through the earthquake with only a couple of hours of down time. This system used battery stored power and gas engine generators to make up the difference while the main grid was out and proved to be a key addition to increasing availability during the outage.

 

What other benefits can we reap from the use of microgrids?

Demand for renewable energy has increased on a global basis and with this there has come an inherent difficulty for incorporating these types of generation into the grid on a large scale. The difficulty stems from renewable sources providing power during their optimal times, such as solar only providing power while the sun is up and wind turbines only providing power while the wind is blowing. What problem does this create for the grid? Energy demand is an instantaneous occurrence which requires supply to meet demand exactly equally. Conventional power generation, such as coal plants, will use rotating turbines to ramp up or down energy to meet the needs of the consumer. Solar and wind on the other hand cannot be changed instantaneously to keep up with this demand. Storage systems such as batteries are critical for providing this aspect with renewable energy but incorporating this on a large scale for the main grid would require an immense amount of storage. By incorporating renewable energy into microgrids the availability of a system can be maintained without relying so heavily on storage because a variety of power generation features can be dispatched when it is optimal for that particular source. The microgrid can be controlled in such a way that the fuel cells and generators only turn on when the wind and solar cannot provide enough power to meet demand. This makes way for renewable energy to be the primary source and nonrenewable energy to be the back-up. As storage systems become more efficient and smaller in scale there will be the opportunity for renewables to take over power generation in full capacity. By using renewables in microgrids it not only provides for an easier transition long term, but also for better access to areas where these sources will achieve greatest output. It is typically not feasible to erect large power generation facilities where ever ones sees fit which makes it difficult to choose the optimal location for large scale solar and wind. By utilizing a microgrid the options for placement become much greater as they have a much smaller footprint.

Another appealing aspect of microgrid conversion is their adaptability to smart grid technology. Smart grids are still a relatively new concept but have been gaining popularity. The idea behind a smart grid is to provide more control to the customer and/or consumer on how and what they use their energy for. It is mainly economically driven but also environmentally driven. There are two schools of thought behind this: one being the customer (the utility companies) and the other being the consumer (households and businesses). The first advent of smart grid technology was smart meters which provided for power usage feedback for the customers and consumers. This enabled people to be more aware of how they use their energy which has inherent benefits for improving energy usage. The next step would be to provide control systems with real time feedback and interfaces for consumers to choose how and when they would like to use the energy they pay for. With a large conventional grid providing power to tens of thousands of households and businesses it is challenging to give each individual any control over how power is produced and managed. Microgrids are inherently local which enables the local community to make decisions which will better suit their needs and provides a level of control which is not necessarily attainable with mass distribution.

Having access to electricity is an often overlooked privilege and the mechanisms that make it possible can be somewhat daunting and mysterious, but they don’t have to be. By using renewable energy such as solar, which can be incorporated in your home, and converting to microgrids with smart technology, any person can take part in how we power our world. With more people involved, the road towards sustainability and efficiency will become easier to travel.

Ally Jackman

 

Kwasinski, A., Weaver, W., & Balog, R. S. (2016). Microgrids and other local area power and energy systems. Cambridge: Cambridge University Press.