Sustainable Microgrids

Sustainable Microgrids

Oct. 23, 2015
Microgrids are being hybridized with renewable generation and energy storage.

Globally, one of the fastest-growing power-delivery technologies is the microgrid, yet when looking for the word on, the search returns: “The word you’ve entered isn’t in the dictionary.” That is remarkable considering how long this technology has been in use by utilities, industrial facilities, military bases and residential customers worldwide. It seems Merriam-Webster’s dictionary needs to play catchup in the technology sector.

Along with providing power-outage protection, these devices have been very successful at supplying black-start power and providing reinforcement of the centralized grid in times of heavy demand. To be clear, a microgrid is a much smaller version of the centralized grid. It comes complete with generation, a control system and load. It is capable of operating in parallel with the utility grid or completely separate from it.

The technology can be found in large metropolitan areas as well as in remote corners of the world and everywhere in between. Microgrids have been part of the utility scene for decades, but extreme weather-related outages such as hurricanes and ice storms, along with weak grids requiring backups, have put the technology front and center.

Today’s microgrid components have a very small footprint and can be installed anywhere in the world. Courtesy of ABB.

The Early Days

When microgrids first appeared, cost was the biggest challenge affecting their deployment, but increased usage has brought down prices and enhanced features have made them more cost-effective and justifiable.

Another factor encouraging the installation of more microgrids has been improved regulatory and utility acceptance, although there is still a way to go. For example, in the United States, federal, state and local governmental entities have not only increased their support of the deployment of microgrids, but many also are offering incentives with their grid-resiliency programs to give the technology a boost.

The U.S. Department of Energy (DOE) has funded an $8 million microgrid program. The DOE’s National Renewable Energy Laboratory (NREL) will be working with companies to develop more sophisticated controllers for microgrids. NREL’s energy system integration facility will be used to test these devices with real-time simulations at full power.

One noteworthy project is located on the National Grid’s system in Potsdam, New York. The microgrid will use local renewable resources as much as possible and have underground components. The proposal calls for a combination of technologies including 3 MW of combined heat and power generators, 2 MW of solar photovoltaic (PV), 2 MW of energy storage and 900 kWh or more of hydroelectric generation.

The Leinster Mine needs both the voltage support of the microgrid and the ability to provide power to its loads. Courtesy of ABB.

It also will include underground distribution lines from the microgrid to its protected loads because of the area’s propensity to ice storms. Prior to Superstorm Sandy, this area held the record for the most damaging weather-related outage caused by the infamous 1998 ice storm.

Clarkson University is designing the underground distribution system, which will be built in parallel to the existing grid. GE is developing an enhanced microgrid control system to integrate these different power resources into a system that can power Potsdam’s protected loads and enable National Grid to use these resources for energy management.

The entire microgrid system will be tested at NREL’s facilities prior to deployment. The goal of the Potsdam microgrid project is to develop a system that can be adapted to other towns and communities susceptible to extreme weather-related disasters like Potsdam’s ice storms.

Microgrid capacity is projected to continue its growth at substantial levels. Courtesy of Pike Research.

Solar Microgrids

One of the most exciting attributes of today’s microgrids is the role renewables have taken in the technology. Environmental friendliness is becoming an important feature to stakeholders. Back in the day, anyone installing a microgrid was limited to generation that burned fossil fuels. Although fossil fuels are used still, the push is on to limit them. Elements like PV solar, wind and fuel cells are being integrated into microgrids.

Interestingly, at the very time the cost of microgrids is being reduced, the prices of PV panels and inverters also have been dropping steadily. This has made microgrid technology very desirable in underdeveloped portions of the world where there is no electricity. A recent paper from the International Energy Agency pointed out more than 1.3 billion people do not have access to electricity. International Energy Agency said getting fossil fuels to those areas can be challenging and expensive, but they have solar and wind resources that can be tapped for electricity.

Not only is this concept popular with remote areas needing electricity, it is becoming important to communities in the developed and developing countries committed to improving their carbon footprint by reducing their dependency on fossil fuels. According to GTM Research, installations of microgrid technology are experiencing record growth worldwide.

In the U.S. microgrid market, GTM predicts the cumulative capacity of microgrids will reach approximately 2.8 GW by 2020. More importantly, that 2.8 GW represents a $3.5 billion investment during that period, which will encourage further development of the technology.

HIS Technology reported approximated 45 GW of PV was installed globally in 2014 and estimates 2015 installations will be in the range of 53 GW to 57 GW.

GTM said, “2014 was a transitional year.” It predicts the Asia-Pacific region will install about half of the projected global installations of PV in 2015. China will install about
14 GW of the region’s projected 30 GW of PV. GTM stated, “Europe will begin an upswing and North America, primarily the United States, will continue its year-over-year growth.”
The Solar Energy Industries Association points out low PV costs are driving the record PV installation. The association also noted most of the major solar companies now offer some form of energy storage with their systems.

Isolated islands such as Kodiak offer unique opportunities to prove the value of microgrid technology when integrating renewable energy into the island’s power grid. Courtesy of ABB.

Microgrids with Storage

Figures from GTM show battery storage technology is currently integrated into 44% of the installed microgrids in the United States. If renewables are playing such a substantial part in the generation component, it only makes sense customers are adding storage to mitigate the intermittency of PV systems.

Storage also improves the capability of a microgrid. Energy storage gives the microgrid an enhanced ability to be used in demand management and energy management systems, but there are more storage options available than batteries.

Alaska leads the world in microgrid deployments, according to Navigant Research. One of the more interesting microgrid installations took place on Kodiak Island off Alaska’s southern coast. Kodiak Electric Association is a rural electric cooperative serving a population of 15,000 with no interconnection to the mainland. Many years ago, the cooperative committed to producing 95% of its electricity using renewable generation by 2020. Today, the majority of its 28 MW of power is produced by hydrogenation and 9-MW wind generation with some diesel backup.

The system also has two 1.5-MW battery systems, so it is truly a hybrid system. The city of Kodiak decided to upgrade its diesel crane to an electrically driven crane with more capabilities than the diesel crane. The electric crane was expected to generate power fluctuations, which could destabilize an isolated grid like the one on Kodiak Island. Something had to be done to the cooperative’s grid to address this issue.

Kodiak Electric Association selected ABB to provide an enhanced microgrid. The system included two ABB 1-MW Power-Store grid-stabilization generators. These devices are based on a fast-acting spinning flywheel technology with ABB inverters to store short-term energy to absorb and inject both real and reactive power onto the microgrid. PowerStore also can be outfitted with batteries or whatever the customer specifies, so it is flexible.

The ABB microgrid provides voltage and frequency support to the Kodiak Electric Association grid. The flywheel component also extends the life of the two battery systems by reducing the wear and tear during charge-discharge cycles caused by the electric crane. Its energy management capabilities reduce the intermittencies from the island’s 9-MW wind farm, which is why this is such an interesting application of hybrid microgrid technology.

Microgrids come in various sizes that can power buildings or much larger areas. Courtesy of ABB.

New Elements on the Scene

There are solar microgrids, wind microgrids and storage microgrids, so it makes sense that we are now seeing combined elements like solar-plus-storage and wind-plus-storage microgrids coming onto the scene. Taking advantage of advancements in microgrid controllers, these new elements can balance the microgrid’s loads with the renewable energy resource’s output.

For example, the solar-plus-storage microgrid offers stand-alone operation and also can provide dynamic energy management in parallel with the grid. Not only is the customer side of the meter taking advantage of the solar-plus-storage microgrid technology, but the utility side of the meter is benefiting, too. One of these microgrid projects was installed in Borrego Springs, California, and recently made history with an unprecedented accomplishment.

Several years ago, San Diego Gas & Electric (SDG&E) received an $8 million grant from the DOE to launch the Borrego Springs microgrid, which is an “unbundled utility microgrid,” according to the utility. SDG&E owns the distribution assets, but some or all of the distributed energy resources are owned by the customers. This was followed by a $5 million grant from the California Energy Commission (CEC) to expand the Borrego Springs microgrid. The project partners included Lockheed Martin, IBM, Advanced Energy Storage, Horizon Energy, Oracle, Motorola, Pacific Northwest National Laboratories and the University of California, San Diego.

The DOE and CEC project is a hybrid microgrid with a total microgrid installed capacity of about 4 MW, made up of two 1.8-MW diesel generators, a 500-kWh/1,500-kWh battery at the substation (which will be instrumental in achieving peak load reduction), three smaller 50-kWh batteries, six 4-kW/8-kWh home energy storage units, about 700 kW of rooftop solar PV and 125 residential home area network systems.

The grants provided funding to increase the size of the microgrid to include all of the Borrego Springs community and tie NRG Energy’s nearby 26-MW Borrego solar facility into the microgrid. The NRG facility provided enough renewable energy to power the entire community of 2,800 customers. This expansion makes the Borrego Springs microgrid one of the largest microgrids in the United States.

In addition to the NRG solar farm, the Borrego Springs microgrid’s distributed generation resources include two traditional 1.8-MW diesel generators and several battery systems that allow the microgrid to fill in the power fluctuations from the solar facility.

After completion of the DOE- and CEC-funded microgrid expansion, SDG&E was able to use the microgrid to eliminate a power outage needed to repair the radial transmission line feeding Borrego Springs. It had been damaged by lightning and the utility estimated the outage time to repair the damage would be about 10 hours.

Early on the morning of May 21, 2015, the microgrid was seamlessly switched, placing the Borrego Springs community on the microgrid’s power. Nine hours later, the maintenance was completed and the microgrid was switched back to the SDG&E grid.
The utility believes this is the first time in the U.S. a solar-based microgrid with energy storage was used to provide electricity for an entire town, avoiding a significant outage. The results were so positive, SDG&E plans to incorporate more advanced computer software and sensors to continue to enhance the microgrid.

Remote villages are hard to supply with fossil fuels making microgirds with renewable generation very desirable. Courtesy of ABB.

Isolated Microgrids

The ability of the microgrid to island itself from the grid and supply power to the community is a huge selling point for the devices. This allows remote populations the ability to be self-sufficient energy islands, which is not the same thing as being cut off from the grid.

For example, Native American reservation communities are not always located close to a utility grid and extending distribution lines can be super expensive, which is why microgrids are considered an attractive alternative to line extensions. GreenBiz reported, “According to the Energy Information Administration, around 14% of households on
Native American reservations lack access to electricity, 10 times higher than the national average.”

The CEC has provided a $5 million grant to help fund the Blue Lake Rancheria microgrid project, located in northern California. The microgrid will be powered by a 0.5-MW PV installation, 950-kWh battery storage system, biomass fuel cell system and diesel generators.

The Blue Lake Rancheria and Humboldt State University’s Schatz Energy Research Center have partnered with Pacific Gas & Electric Co., Siemens, Idaho National Laboratory and REC Solar to build this low-carbon microgrid. It will provide electrical power for the reservation, including tribal government offices, economic enterprises and a Red Cross safety shelter.

Siemens is implementing its Spectrum Power 7 Microgrid Management System to dynamically manage and control the distributed generation resources providing power to the microgrid. The installation of the microgrid will be completed in 2016 and will enable the Blue Lake Rancheria microgrid to operate independently from the Pacific Gas & Electric Co. grid in the event of an emergency such as an earthquake. The microgrid project is being used to prove the validity of using microgrid technology to address limited access to electricity on tribal lands in more remote locations.

In Africa, the potential of microgrid technology has just begun to be realized. Studies report that some areas of Africa have very good conditions for constant wind energy, not to mention solar resources. That makes microgrid technology very valuable for renewable energy integration and the most cost-effective solution to provide electricity to local communities. One of those areas is Marsabit, an oasis at the edge of the desert in a windy area of northern Kenya with a population of 5,000 that is not connected to any national grid.

Located on top of a windy hill, a diesel generator has been the only generation source producing electricity. Socabelec East Africa Ltd. has decided to add wind turbines to the existing installation and to stabilize the resulting microgrid through ABB’s PowerStore. The grid-stabilizing generator will interface with both diesel power station and wind turbines and will allow for maximum penetration of the clean wind energy so to reducing reliance on fossil fuel and emissions.

Microgrids are not just for remote locations or isolated networks. Buildings can require microgrids, too, especially when they need to provide for their own power needs. This condition is very common in countries where the main power grid is under-dimensioned or cannot keep up with the fast pace of additional power demand.

In such countries, many buildings, facilities and industrial sites are forced to install their own generation plants to ensure uninterrupted power supply when main network faults occur. ABB’s offices in Longmeadow, Johannesburg, South Africa, meet these requirements. This building will have a microgrid with a PV energy source, an integrated diesel generator and storage batteries. It is being used to demonstrate microgrid technology to the rest of the African continent.

The key to successful microgrid deployment is having the necessary components for the project. Courtesy of ABB.

Mainstreaming Microgrids

There has been a great deal of activity in the microgrid world in the past five years. The technology has moved from a specialized niche to being a mainstream utility grid asset. The cost of distributive generation continues to drop. In many parts of the world, solar generation costs are equal to or below that of utility-generated electricity, which has been a great incentive for the adoption of microgrid technology to integrate this generation into the transmission grid.

Microgrids differ from the centralized grid by providing closer proximity between generation and the load. Their capabilities have increased in both depth and dimension as the technology evolves. With the addition of renewable generation and storage components, microgrids have reached a new level of complexity.

Customers may have solar, wind, fuel cells, hydro or a combination of these plus other types of generation resources. If they do, they will want to blend them into a sophisticated mix of environmentally friendly resources. The customer expects the manufacturers to develop resource management systems to control and protect such a mix, which they have.

Storage has played a significant part in this process, too. Like the variety of renewable generation available, energy storage has many existing technologies to meet the demand. The principal storage technology used with microgrids has been the battery, but that has many offshoots such as advanced lead-acid, nickel-cadmium and lithium. There also are systems coming available with flywheel storage, hydrogen storage and ultracapacitors, to name a few.

Each renewable and energy storage technology has its own particular pros and cons, which need to be understood, addressed and controlled to attain their fullest potential. Today’s microgrid is definitely not the microgrid of yore. It may bear the same name, but that is the only commonality. The mega grid has its shortcomings and problems, but one of the most promising solutions to these foibles is the microgrid and the modularity it can provide with all its bits and pieces.

Sidebar: The GRID4EU Project

Electricity has been around for a long time. In fact, so long that we constantly hear the electrical grid is old and out of date. There have even be comments about how Thomas Edison would be at home in any substation or generation plant used today. If you think about it, that just isn’t true. Sure, the basic components are similar to devices used in those early days, but that appearance is only skin deep.

Today’s digital grid is a smart grid, and it’s getting more intelligent all the time. As this technology unfolds, there is a great deal of talk about the electrical grid of the future. It is an exciting topic and many have let their imaginations run wild with science fictional ideas, but in the European Union (EU), they are doing more than talking about it; they have decided to take an active approach rather than the reactive posture many others in the industry accept.

GRID4EU’s six major European distribution system operators. Courtesy of GRID4EU.

The European Commission proposed a large-scale demonstration of distribution networks with distributed generation and active customer participation several years ago. It took form in 2011 as the GRID4EU project. Six major European distribution system operators (DSOs) pooled their expertise and answered the commission’s proposal. These DSOs represent more than 50% of the metered electricity customers in Europe, and they have a enormous stake in how the grid will develop as more advanced smart grid technology is deployed.

The DSOs represented in the GRID4EU project are the CEZ Distribuce (Czech Republic), ENEL Distribuzione (Italy), ERDF (France), Iberdrola Distribucion (Spain), RWE (Germany) and Vattenfall Eldistribution (Sweden). The project is designed to develop and test new innovative technologies. It will also advance standards for these technologies with real-world experience.

In addition to the six DSOs, there is a unique partnership of 27 energy suppliers, manufacturers, system integrators, research centers and universities from the EU taking part in the project. This is the largest smart grid project in the EU. The GRID4EU project has received 25 million euros in EU funding and 29 million euros in industry funding.

The GRID4EU consortium. Courtesy of GRID4EU

The project consists of six different pilot projects taking place in six different countries that seek to complement and enhance each other. GRID4EU will test the potential of new technologies in areas such as renewable energy integration, resiliency, electric vehicle development, demand side management, microgrids and energy storage. It will also work toward improving peak load management, energy efficiency and load reduction, and keeping the whole system balanced.

What makes the project unique is its approach. Overall, it is a large-scale demonstration project that has to be scalable and can be replicated over the entire European grid. What makes GRID4EU standout from the pack is the innovative methodology being used. There are many partners involved with the six pilots and all are working together in an effort to share the results of each of the pilot projects for their mutual benefit and improvement of their common knowledge.

Interactions and synergies between demonstrators. Courtesy of GRID4EU.

The utility industry members of the EU have taken seriously the application of this developing smart grid and microgrid technology. The GRID4EU project will take a great step forward defining that grid of the future. It will require an integrated system of all these developing and developed technologies. We have the tools in the toolbox, but combining them into one cohesive future grid is the challenge. GRID4EU has taken that challenge and is raising the bar for the rest of the industry as it moves toward completion.

About the Author

Gene Wolf

Gene Wolf has been designing and building substations and other high technology facilities for over 32 years. He received his BSEE from Wichita State University. He received his MSEE from New Mexico State University. He is a registered professional engineer in the states of California and New Mexico. He started his career as a substation engineer for Kansas Gas and Electric, retired as the Principal Engineer of Stations for Public Service Company of New Mexico recently, and founded Lone Wolf Engineering, LLC an engineering consulting company.  

Gene is widely recognized as a technical leader in the electric power industry. Gene is a fellow of the IEEE. He is the former Chairman of the IEEE PES T&D Committee. He has held the position of the Chairman of the HVDC & FACTS Subcommittee and membership in many T&D working groups. Gene is also active in renewable energy. He sponsored the formation of the “Integration of Renewable Energy into the Transmission & Distribution Grids” subcommittee and the “Intelligent Grid Transmission and Distribution” subcommittee within the Transmission and Distribution committee.

Voice your opinion!

To join the conversation, and become an exclusive member of T&D World, create an account today!