Microgrids, Distributed Energy, and Resilience

Wednesday, January 31, 2018

Four months after Category 5 Hurricane Maria swept through Puerto Rico causing catastrophic damage, much of the island is still without power, food, and water. The storm knocked out power to almost all the commonwealth—homes, schools, hospitals, and other critical services and infrastructure were left without power. Even now, over one-third of the island is still without electricity, and many are left without access to food and running water.

Destruction of the energy infrastructure on the island of Dominica, following Hurricane Maria (Photo: Wikimedia Commons)Electricity is essential to meeting residents’ basic needs. Carmen Maldonado, mayor of Morovis, explained that 80% of her town is without electricity—and that residents have been forced to purchase fuel for power generators, leaving them less money for clean water and food. And, without refrigeration, many Puerto Ricans are forced to rely on FEMA for delivery of food.

Reducing Vulnerability Through Distributed Energy

Microgrids—a group of interconnected loads and distributed energy resources that can connect and disconnect from the grid—may provide a solution to reducing vulnerability and improving resilience in the wake of a changing climate and increasing risk of natural disasters. In the aftermath of the recent tragedy, Puerto Rican officials have been discussing potential plans for privatization and improvement of the island’s grids. Battery companies Tesla and the German-microgrid company Sonnen have discussed plans to increase production of battery production, and have announced plans for developing microgrid electricity distribution systems for Puerto Rico.

Superstorm Sandy

Superstorm Sandy provides yet another example of the risks of extreme weather events to our energy grid—nearly 8 million households were without power. For nearly two weeks, large stretches of the Northeast including parts of New York City suffered loss of power, and resulted in over $70 billion dollars of lost business. Some district energy systems, however, were able to withstand the storm, illustrating how local resources can be optimized in such an extreme weather event.

For example, New York University continued to supply power through its use of a distributed heating system. Although not technically a microgrid, this distributed heating system reflects how distributed energy systems—small-scale power generation or storage technologies—can increase resilience, particularly as a changing climate brings more extreme weather events and greater potential for loss of power. Indeed, the success of distributed energy during Superstorm Sandy spurred the state of New York to provide $500,000 to utility companies serving four of the state’s municipalities in order to launch feasibility studies on the implementation of microgrids.

Microgrids on Skids

With studies showing that microgrids and other methods of distributed generation can increase our resilience in the wake of global climate change, it seems clear that microgrids are a viable solution and one that will be increasingly employed in the future. But the path toward more resilient and distributed generation energy systems will be a bumpy one. The microgrid industry faces numerous hurdles, such as gaining acceptance from utility companies and regulatory impediments. Another problem to solve is how to quickly integrate resilient microgrids into our energy systems.

Japanese multinational Hitachi recently stated that the microgrid industry needs to develop a small, modular solution able to be designed and created in a “controlled environment” and then sent out and installed within a day. This “grid on a skid,” which could be designed in a few variable sizes, could allow microgrids to be set up in areas very quickly. Such a system would likely use technology such as a contained, combined heat and power (CHP) unit, photovoltaic solar panels for installation on rooftops, and energy storage and control units.

The War of the Currents

The increasing severity and frequency of extreme weather events, in addition to risks of cyber and other attacks, as well as electric grid malfunctioning, all pose threats to our electricity transmission systems. These risks merit a revisiting of the debate surrounding AC and DC power, a discussion that goes back to Thomas Edison and his former employee Nikola Tesla in the 1880s.

Now referred to as the “War of the Currents,” this debate began because Edison developed a direct current—DC—that runs continuously in one direction, similar to a battery, and became the standard during the first few years of electricity in the United States. Because direct current is more stable than AC, it can be used to transport electricity farther, and results in greater efficiency because of reduced electricity loss.

George Westinghouse, along with Tesla, on the other hand, felt that an alternating current—AC—was a better solution as it is easier to scale up. Whereas DC is difficult to convert to lower or higher voltages, an alternating current can change direction multiple times per second, and thus can be changed to different voltages through a transformer.

To date, AC has mostly won out in terms of electricity generation—for example, in 1893, Westinghouse and Tesla built a power plant at Niagara Falls to harness hydroelectric power for New York City using AC power, winning out over DC-based proposals. Today, however, our computers, LED lights, and electric vehicles all use DC power.

DC Power and Microgrids

This debate is being revisited a century and a half later as studies are examining how AC and DC power could be used in tandem. Recent catastrophic weather and increasing risks to our electricity systems have in particular sparked discussion on how combined approaches can increase grid resilience and efficiency, enable use of newer and cleaner energy technologies, and even potentially reduce consumer costs.

Appliance company Bosch has developed a new microgrid system that uses DC, which they claim can provide “significant energy efficiency, cost, reliability, and safety benefits” as compared to the conventional AC systems. In this novel microgrid, distributed generation such as solar photovoltaics are directly connected to energy-efficient DC lighting and ventilation, and can therefore maximize the efficiency of locally generated energy. Additional power can be supplied through an AC/DC converter that can offer additional power when locally generated energy is not sufficient to supply the load.

Solar power is particularly interesting. Solar is a type of DC power, but it uses the “photoelectric effect,” where energetic light causes electrons on the surface of a material to be dislodged, thus creating a negative charge. However, this negative charge doesn’t run out as long as there is radiant light. This type of DC power is therefore a non-exhaustible energy source.

One thing is certain—when planning for a future with increasing climate variability and extreme weather events, microgrids play a key role in ensuring electric grid resilience and reliability.


This blog is based on Miriam Aczel’s original piece published on the Leaders in Energy blog, available here: https://leadersinenergy.org/microgrids-distributed-energy-resilience/.