Understanding the Benefits of Microgrids

4/24/2023

Microgrids are not a new facility strategy but they’re an increasingly beneficial one. What are microgrids? Microgrids are small-scale power grids that can operate independently or collaboratively with other small power grids. Facilities that strategically use microgrids in their facilities can operate independent of the macrogrid for a period of time. This means, depending on the sophistication, certain critical pieces of can continue operating. Microgrids can range in size from a single zone in one facility to multiple facilities spread over several blocks or miles.   

As beneficial as microgrids can be for facility resilience and a number of reasons, they are not plug and play strategies. Facility managers have a number of considerations for implementing microgrids effectively. 

FacilitiesNet recently spoke with Brian Patterson, founder and chairman of the board of the Emerge Alliance, an organization founded in 2008 to promote the adoption of new vanguard standards for direct current (DC) and hybrid AC/DC power infrastructure in buildings, neighborhoods and communities. Patterson discusses how microgrids are an increasingly important facility strategy. 

FacilitiesNet: Please explain the benefits of microgrids. 

Patterson:

• Microgrids can remove capacity constraints of power availability by adding new power capacity generated at or near the grid edge. Today, depending on where your business is located, power from the local utility may be limited and delays of up to two years or more have been reported. Because of their power electronic conversion and management capability, they facilitate a greater use of multiple and/or combined clean renewable energy sources. 
• Provide shared and reserved storage capacity at the grid edge which can buffer/bridge power loss from the grid, storing clipped power from solar or wind generation that exceeds real-time load or grid needs, and provide extra power for peak load curtailment. 
• More easily incorporate new, natively DC generation, storage, and loads like H2 fuel cells, long duration flow batteries, variable speed brushless motor loads like heat pumps, air handlers and compressors, electronic loads and robotics, micro data centers, etc. 
• Be non-synchronous DC-coupled which makes them self-grid forming with no dependance on grid connection for frequency regulation and synchronization 
• Be networked in self-healing/configuring mesh topologies, typically DC-coupled, which allows a bottom-up semi-autonomous supply and demand balancing. 
• Operated with semi-autonomous distributed control, which can fail safe in a fully operation mode without reliance on central or hierarchical control from other grid operators 
• Provide AC grid support at the distribution edge because of its independent capability to broker grid support based on its own internal needs 
• Enable “Energy as a Service” differentiation and capability because, properly architected in dc or hybrid ac/dc, they are natively capable of delivering various power quality levels and forms, including pure sinewave ac, isolated and highly regulated dc, class 4 fault managed dc (touch-safe digital electricity up to 450 V line to line and 225 V line to ground) and even native ELVDC dc power, power over ethernet (PoE), and USB Power Delivery (USB-PD). 

FacilitiesNet: Why is DC and/or hybrid AC/DC a resilience strategy? 

Patterson: Resilience can be defined as the ability of a power system to either ride-thru or quickly recover from a disturbance or threat that would otherwise cause a sustained power loss.  DC and/or hybrid microgrids are typically locally deployed power systems that can easily and quickly disconnect from a grid-down power loss or disturbance, regardless of whether the grid power loss was caused by physical or cyber damage to the macrogrid. DC and hybrid AC/DC microgrids have the advantage of being non-synchronous (DC-coupled) and therefore do not rely on an external frequency (the macro grid typically at 3 Phase 60 HZ) to continue operation.  This is very different than other grid connected distributed energy resources like standalone solar arrays, storage systems, fuel cell generators, etc. that rely on the grid for black-start capability. 

FacilitiesNet: What steps should facility executives take to implement a microgrid(s) in their facilities? 

Patterson: Whatever process is used to implement a microgrid, it should include considerations that can achieve the highest efficiency, the lowest risks, the lowest carbon footprint, and the most cost-effective energy solution. Depending on in-house expertise, either a pre-packaged or engineering firm provided approach could be used. Some planning approaches provide once-and-done engineering and the more advanced approaches incorporate digital-twin engineering. The more complex or larger in scale, the more the planning should be comprehensive, including digital twin modeling and management. A basic framework for microgrid planning is offered by the Smart Electric Power Alliance (SEPA) and includes the following areas of consideration: 

• Identifying roles and responsibilities and considering regulatory implications. 
• Understanding the use case needs and analyzing the proposed site. 
• Collecting and analyzing energy consumption and load profile data. 
• Considering customer resiliency needs and screening for different solutions. 
• Considering economic factors that impact the user and/or utility. 
• Identifying potential microgrid services and operating modes. 
• Considering different fuel mix approaches. 
• Identifying possible microgrid assets. 
• Determining the sizing and capacity of the microgrid 
• Conducting engineering and interconnection analysis. 

Ideal pre-planning would further include: 

• Financial Modeling 
• Risk Management Review 
• Legal Review 
• Market Participation Opportunity Analysis 
• Zoning Opportunity and Requirements 
• Identify Key Vendor/Partners Required for Each Engagement 
• EaaS Operations 
• Maintenance Planning 

In the specific case of DC and Hybrid AC/DC microgrids can benefit by a new design tool called DCide, which is in pilot introduction and beta testing in the market by Direct Energy Partners in coordination with the EMerge Alliance. It is intended to be based on and in compliance with new EMerge microgrid standards now in development.   

Greg Zimmerman is senior contributor editor for the facility group, which including FacilitiesNet.com and Building Operating Management magazine. He has more than 19 years’ experience writing about facility issues.