Twentynine Palms already has 7 acres of solar photovoltaics (PV) that total more than 1 MW, as well as a gas-fired cogeneration plant in excess of 7 MW. In the future, additional solar PV, fuel cells and advanced energy storage systems may also be added to the marine base’s on-site resource mix. GE has helped design a microgrid control strategy– for the largest microgrid in the U.S. among DOD sites – managed by a platform based on existing GE controls already utilized for smart substations. The controller is flexible and can manage other “smart” distributed resources, including inverter-based sources, through proprietary algorithms.

Local generation sources, power from the utility grid, and the marine base’s load demands will all be monitored and coordinated using the configurable logic of GE’s Multilin Universal-Plus relay (See Figure).  The relay’s algorithms will enable mixes of renewable energy, fossil fuel generation, and grid power to be balanced at different times.  In addition, loads can be better predicted and prioritized during periods of higher consumption or islanded conditions.  With this controls architecture in place, Twentynine Palms can optimize on-site resource while in grid-connect mode, but also extend its operations capacity and maintain high performance in an off-grid situation. Since the GE controls technology is flexible, it also may be able to be deployed in mobile microgrid applications. (The company is already deploying the same controller in a smaller remote community microgrid of approximately 4 MW (winter season) in British Columbia known as “Bella Coola.” For more details, please visit http://www.genewscenter.com/Press-Releases/Clean-Energy-Powers-Bella-Coola-B-C-2ac3.aspx)

GE and the ESTCP Office wish to certify the technology using the Twentynine Palms base as an evaluation vehicle for future microgrid development enabling widespread implementation across the more than 400 bases within the US. The microgrid with its advanced supervisory control technologies is being viewed as one of the premier examples of the environmental and energy surety technologies yet to be deployed by the military. It is one of the first to incorporate variable renewables and is beyond the scale of most pilot projects, which typically fall in the sub-megawatt range.

Consider a campus, with multiple buildings that are currently served with electricity from the local utility, utilizing natural gas through a boiler system for heat generation. The yearly operating cost of this campus includes electricity costs, natural gas costs and maintenance costs and is represented with the red line. Our study then evaluates the transformation of the campus to a Microgrid with an on-site Combined Heat and Power (CHP) facility that generates both electricity and heat.

This CHP system is grid-connected, and allowed to purchase electricity from the utility using a real-time pricing structure. This means the utility at this location allows the electricity price to vary during the day. Our advanced energy management technology then determines when to make electricity and heat locally, versus buying from the utility and Gas Company when rates are advantageous. The operating cost of the Microgrid system is shown in green, and demonstrates greater than 40% reduction from the current operating mode, made possible by the high efficiency of the CHP system and the benefits of participating in the local electricity market.

So what are microgrids? Microgrids are power systems that utilize locally available power generation resources to service part or all of the local loads. These systems may or may not be connected to the bulk grid that are maintained and operated by the utilities.

Some examples of microgrids can be campuses with several buildings or a group of houses in a residential complex or even a remote village with residential and commercial loads. Microgrids can be designed to be able to operate in a normally grid-connected fashion, with the ability to separate from the grid and operate in an island mode as well. The power generation assets in Microgrids can be diverse; energy can come from renewable resources like wind turbines or solar panels, it can come from conventional resources such as reciprocating engines or gas turbines, or it may come from Combined Heat and Power (CHP) systems which not only generate electricity but also thermal energy. Microgrids may also contain assets like energy storage (e.g. batteries, pumped hydro, compressed air etc.) and controllable loads (e.g. water treatment). A conceptual diagram of a microgrid is shown above.

There are different hierarchies of intelligence that are needed to operate a microgrid. First there are controls, which are exercised at the level of each asset, these are called ‘local controls’. Then there is the Energy Manager – which supervises all these assets on a system level and manages the overall objectives of the microgrid operator. The usual objective is to optimize operating performance and cost in the normally grid-connected mode, while ensuring the system is capable of meeting the performance requirements in island mode. So the Energy Manager is not only the ‘glue’ that binds all these assets on a system level; but also provides additional benefits in cost and performance, which help in promoting more penetration of renewable energy resources and thereby reducing dependence on fossil fuel.

In this program, GE is working with the US Department of Energy to develop advanced controls, energy management and protection technologies for Microgrid applications. In my next entry, I will give you a good example of the economic benefits that can be achieved through the use of microgrid. Stay tuned.

As Juan talked about in his blog entry, one of the key areas our Lab focuses on is the technical challenges with incorporating renewables like wind and solar into the electric grid. Grid integration is becoming an increasingly important issue as renewables become more widely utilized. And there’s no question about the great potential for renewables growth in the U.S.

I wanted to share with you an exciting project we are working on here at Global Research in offshore wind. GE will design and develop an optimized multi-megawatt turbine system targeted to operate in offshore environments.

Under a $27 million partnership between GE Global Research and National Renewable Energy Laboratory (NREL), GE is embarking on a four-year Low Wind Speed Turbine Phase II Development program. The goal is to develop technologies for a multi-megawatt offshore wind turbine prototype with high reliability and availability at agreed cost goals. The program will identify innovative solutions for new foundation types, construction techniques, rotor design, drive train and electrical system while optimizing the total life cycle cost of offshore wind farms. Turbine design and actual prototype will incorporate best technology practices from land-based turbines while incorporating lessons-learned from first generation offshore pilot projects to develop a new robust turbine concept optimized for offshore operations. Optimum turbine size is expected to be in the 5-7 MW range suitable for more than 20m water depth.

We’re very excited to be working on such a huge project here at Global Research. The design of a next generation offshore wind turbine will help advance the wind industry and greatly expand wind energy potential here in the U.S.