Microgrids: A Primer

Introduction A number of distributed energy trends add up to increased interest in microgrids. The objectives and value propositions include access to renewable resources for energy and environment, a more resilient electricity supply amidst storms, optimized energy use by local generation and by local control. Individually these objectives are already being served in various applications and with available distributed energy technologies. A prominent example is roof-top photovoltaic (PV) systems. Widely deployed and custom fit to end-user's sites these systems rely on the grid for balancing differences in output and demand. Also common, battery energy storage and standby generators protect critical processes in applications like hospitals and computer centers. Commercial combined heat and power (CHP) systems usually serve local heat requirements with power to the public grid as a byproduct. Nothing new here, but put them together with a grid connection and a control, and you have the makings of a microgrid. In concept microgrids employ an integrated approach that captures the benefits of several distributed resources. They may provide value to both producers and end users. It's a good concept, but still, the extent of adoption will depend on many factors such as renewable policies, the weather and the price of natural gas. Also future advancements in distributed energy technology and product options are expected to bring improved economics. Ease of grid integration will also be a critical factor in deployment. The challenge, and opportunity, is to create a safe and effective operational collaboration. Utilities can play an important role here. Considered from the broader system viewpoint, harnessing distributed resources can add both flexibility and resiliency to the electric power grid. This primer reviews the drivers for distributed resources and their extension into a microgrid configuration. It explores barriers and challenges for adoption including technical, economic and regulatory. Technologies expected to improve performance or support integration are identified. The primer touches on ownership and business models as well as the likely end-user candidates where a microgrid may contribute to uptime and overall energy efficiency. Finally, it discusses the future for microgrids and points out ways utilities can strategically incorporate them into the larger grid operations.