Novel Direct Current Architectures Face Challenges in New York, California
If I had to pick two states that are leading the charge on reinventing electric utilities they would be New York and California. Yet even in these state laboratories of regulatory reform, new novel forms of distribution networks often referred to as “microgrids” that rely upon the inherent advantages of direct current are facing obstacles.
The core challenge facing DC distribution networks lies with the need for standards and open grid architectures that can help integrate the increasing diversity of resources being plugged into retail power grids. This, among other issues, is the focus of the first major conference sponsored by the Institute of Electrical Energy Engineers (IEEE) on DC distribution networks taking place in Atlanta, Georgia on June 7-10th of this year.
In New York, a privately held company with approximately 10 employees, Pareto Energy of Washington, DC obtained preliminary engineering approval from Con Edison and a $2 million grant from NYSERDA with which it has begun installing its patented GridLink at the 12.8 MW CHP plant that serves Kings Plaza Shopping Center on the Brooklyn waterfront. GridLink converts power from each generation source (including grid power) from AC to DC, collects all the power on a common DC bus, converts that DC power back to AC, and distributes power to any load (including those on the utility grid). All the while, each power source is electrically isolated from one another. In short, GridLink creates a non-synchronous plug-and-play microgrid, thereby obviating the need for time-consuming and expensive interconnection studies required for many distributed generation projects.
Although the Kings Plaza has never been connected to Con Edison’s grid, it provides both electric and thermal energy to the center as costs that are less than half of the alternative of using Con Edison’s grid for power and boilers/chillers for heating/cooling. Under the plan, Pareto’s GridLink is designed to export 8 MW of low-cost power from the King Plaza’s CHP unit to the utility grid at a cost savings of nearly 40% compared to status quo synchronous interconnection. In addition, the site may be utilized to serve nearby low-income communities during a major power outage, serving the public purpose of community resilience.
Despite these impressive potential benefits, some regulatory snags have delayed the project, and Pareto has filed a protest at the New York Public Service Commission claiming discrimination against an innovative and lower cost option to traditional power delivery infrastructure to meet contingency requirements for reliability within the Consolidated Edison service territory.
In California, the issues are different, but they also involve DC. In this case, Bosch, which was awarded a California Energy Commission grant of $2.8 million grant this year to develop a high penetration solar PV DC microgrid at an American Honda Motor Co. parts distribution center in southern California. The project is designed to validate the efficiency performance benefits of a patented system allowing to directly connect DC power flowing from solar PV to LED lighting and DC ventilation systems located within the building, as well as a DC energy storage device. The benefits of DC attached to this project include lower installation and operating costs. In addition, this project is pioneering the application of a DC distribution network within existing building codes in order to boost reliability, reduce consumption, fully utilize solar power to meet approximately the full load of the building, thereby capturing resilience benefits via sustainable networking.
While Bosch observes it has not run into any problems with building codes or other such potential obstacles to its DC building grid business model, they have identified an interesting dilemma. Since state subsidies for both solar PV and energy storage are linked to the size of the inverter interconnecting with the AC grid, DC technologies are being discriminated against, despite the fact they are more efficient and reliable.
In both cases, the status quo is being challenged by new technology revolving around a nonsynchronous microgrid incorporating the advantages of DC, the subject of next report to be published this coming June.