Advanced micro-grids: improving resilience

Advanced micro-grids are helping American energy systems to respond to disruptions more effectively. They can also improve the quality of life for people in the developing world. Sandia National Laboratories’ Mike Hightower updated Energy Ireland delegates on its research.

Mike Hightower is a distinguished member of technical staff at the Sandia National Laboratories in Albuquerque, New Mexico. The labs are operated by Sandia Corporation (a Lockheed Martin managed company) and owned by the US Department of Energy.

Over the last 10-15 years, he explained, energy had been recognised as a major driver for the economy and national security. Many countries were now interested in how to achieve long-term energy security but needed to balance this against the intermittency of using indigenous renewable energy.

Sandia’s research is increasingly looking at how energy systems can handle “abnormal environments” such as cyber-security attacks or natural disasters. The number of severe weather events affecting energy supplies in the USA doubled between 1997 and 2007 (to around 50 per year) and was followed by a spike of 100 incidents in 2008.

Advanced micro-grids have been a major focus of Sandia’s research on energy assurance. Essentially, these are designed to operate in both an islanded and grid-tied format and are based on big data. The research question being addressed is: “Can you use the automation, active management, smart metering, smart grid technologies in a distributed fashion to improve overall reliance [and] energy assurance?”

These types of micro-grid systems could be used as the “building blocks” for a smart grid in the United States. American utilities can serve up to 5-10 million customers and are generally not used to working with big data. The utility companies want to divide their customer base into smaller neighbourhoods or commercial sectors so that IT companies (e.g. Cisco and IBM) could process that data.

Utilities could then use the load and demand data from 60-70 aggregated micro-grids (5-20MW in size) to make their decisions and help manage their energy production. Integrating and aggregating those micro-grids and adding a point of common coupling creates more opportunities for renewable and distributed energy generation and storage that can help increase the system’s reliability, availability, and sustainability.

“Much more sophisticated cyber-security controls” are possible with micro-grids, where the utility is primarily dealing with 60-70 entities rather than 200 million entry points. “It’s a scalable implementation and aggregation of these technologies which, from our standpoint, looks like it can be quicker, faster and cheaper than trying to do this on the transmission side or trying to do it in one large fashion.”

Sandia’s R&D on micro-grids is currently focusing on distributed generation and energy storage integration for military and commercial applications. This covers load management and control strategies, cyber-security, and the safety requirements for integrating renewable electricity technologies.

Energy security is a priority for the military whereas commercial customers often prioritise energy reliability and resiliency.

The SPIDERS (Smart Power Infrastructure Demonstration for Energy Reliability and Security) is one of its most mature programmes. Three major demonstrations are under way:

• Pearl Harbor and Hickam Air Force Base, Hawaii;

• Camp Smith, Hawaii; and

• Fort Carson, Colorado.

Pearl Harbor’s micro-grid became operational in December 2012 and has a 20 per cent renewable energy share from a 1MW system. The Fort Carson project, becoming operational in October, will have 40 per cent renewables from a 3MW system. The Camp Smith project, to be completed in May 2014, will involve demand-side management and electric vehicle integration for a 5 MW system.

Combined cooling, heating and power systems (CCHPs), which have proved popular in Europe, are seen as an important way to improve energy efficiency in the USA. Automated micro-grids show great flexibility but control, management and cyber-security are “concerns that are becoming important.”

The use of islanded and grid-tied networks can greatly improve the return on investment of both distributed energy and storage resources. Coupling, networking and federating micro-grids is also seen as a way to enable better use of distributed energy and storage resources.

Currently 3-10 MW size micro-grids are being considered by utilities as a good scale for both performance and cyber-security trade-offs. Sandia is looking at coupled advanced micro-grids for large countries and utilities as one of the best approaches for accelerating smart grid integration.

Local power for developing countries

Interviewed afterwards, Hightower added that if micro-grids can be designed to operate efficiently with 50-60 per cent renewable penetration, almost every part of the world has the chance to have a reliable power supply. The UN estimates that 1.6 billion people (23 per cent of the world’s population) have no access to electricity.

Micro-grids have real potential to improve the quality of life in Africa, South Asia and other parts of the developing world. With energy being generated “on the roof, in your back yard or down the block,” it would become easier to deliver low cost water and waste water treatment and reduce carbon footprints.

Demand response was an important aspect: “You’re actually going to make it so that people can reduce their energy costs significantly, if they are smart.” He also praised the EU’s commitment to growing renewables. “From the United States, we see that Europe doesn’t have as much renewable potential and yet they’re pushing forward very quickly.”

Micro-grid standards