Microgrids: Complexity Worth the Investment

April 24, 2023
Andreas Görtz, President, Sustainable Power Solutions, Rolls-Royce Power Systems discusses the complexity of microgrids and how embracing complexity can help overcome the obstacles.
During a recent interview, I was asked why microgrids haven’t become a larger part of the world’s energy mix given that the concept has been around since the 1990s and seems to offer so many advantages. My answer was simple: complexity. A microgrid isn’t a product, but rather a complex solution to an energy challenge. It is made up of multiple inputs with various considerations. While the benefits provided by microgrids are very attractive – energy independence, grid stability, efficiency, decarbonization – to be successful, microgrid operators must understand that there is also a great deal of complexity that is required to realize these benefits.

At its heart, a microgrid is a combination of two or more distributed energy resources and energy storage that are connected by a smart controller. While this sounds simple enough, the complexity comes in determining which distributed energy resources are the most applicable for considerations such as the space available, the power needed and the natural resources to be harvested. There are many questions to be answered. How much space is available for battery storage? What is the average harvesting factor for natural resources such as solar and wind? How much power needs to be generated from traditional sources such as diesel and gas or even hydrogen gensets? What is the cost of fuel in the area where the microgrid will operate? With answers to these questions plugged into multiple simulations, we can get to the starting point for designing an effective microgrid.

You may be wondering if all this complexity is worth the investment, and you wouldn’t be wrong to do so. There are easier ways of securing power through more traditional means. The complexity becomes worth the investment when you look at larger goals such as decarbonization, energy flexibility and, of course, cost optimization. Even more compelling is that you can build a microgrid around your existing power system by adding storage and photovoltaics (PV), for example. In such a scenario, you don’t need to replace your diesel or gas system to achieve lower emissions and cost savings. By reducing the run times of your traditional systems through use of stored energy from renewable sources, you save on both fuel costs and emissions.

We recently commissioned a microgrid solution for a logistics park in the United Kingdom. This particular solution addressed the national energy grid constraints in the area, while also offering a sustainable power supply for the logistics park’s tenants, which was highly attractive. We installed two mtu QL EnergyPack battery energy storage systems with 2.3 MWh total capacity to provide a fast, flexible and carbon-free response to varying load demands. Fed by the installed rooftop solar panels, the EnergyPacks act as the sole source of power in times of low demand. Three mtu Series 4000 L64FNER combined heat and power systems, which provide the main power source with 3 MW total power, are also future-ready as they are capable of being converted to hydrogen power. Two backup 1 MW mtu 16V2000 DS1250 generator sets ensure power security in the event of an emergency and add black start ability.

All the mtu systems and on-site solar PV are coordinated by a smart mtu microgrid control system consisting of two microgrid controllers operating in duty and standby mode for added resilience. The system handles both the dynamic load and power needs for optimal commercial and technical efficiency. The microgrid operates in parallel with, and supplemental to, the grid supply and can also operate off grid, if required. With the mtu smart controls, the microgrid provides energy using the best source or combination of sources at any given time. With this solution, the customer expects to realize a savings of between 5% and 10% on grid energy bills and the microgrid is also upgradeable if extra power is needed, such as by adding additional PV.

The project I just described was not an easy one. It was quite complex and required a great deal of coordination, communication, simulation and negotiation to finally deliver. In the end, a successful microgrid is worth this complexity to realize the benefits of flexibility, decarbonization, energy independence and, in this case, cost optimization. By embracing complexity from the start, all parties can work together to overcome the challenges and realize the many benefits a microgrid solution has to offer.

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