Electronic Design

How Three Companies Established Smart Grid Leadership

Bloom Energy, Silver Spring Networks, and Maxim have taken leading positions in the Smart Grid technology marketplace.

The Smart Grid has been in the news for several years now, even though most people don't know what it is (see "What's The Smart Grid?"). But that hasn't stopped several semiconductor companies from staking out a serious position in designing and marketing products for it.

These companies have established their presence with front ends and microcontrollers for electric meters and ZigBee chips for the home-area network (HAN). Three companies have been particularly aggressive—the comparatively unknown Bloom Energy and Silver Spring Networks and the more familiar Maxim Integrated Products.

BLOOM ENERGY's FUEL CELLS

Two years ago, Bloom Energy introduced a solid-oxide fuel cell (SOFC) ac generator in a form factor roughly the size of a gas- or diesel-powered standby generator (Fig. 1). A vital difference, however, is that these SOFCs must operate full-time, not on an emergency basis, at a very high temperature. They also can't be turned on and off instantly. Many of these SOFCs have been deployed at large corporations.

In fact, Cypress Semiconductor is using them to operate its facility in San Jose (see "Cypress CEO T.J. Rodgers Declares Independence From The Power Grid"). The Bloom Energy Servers at Cypress run on methane (natural gas) and provide higher efficiency (51% versus 47%) than even the most efficient three-stage, gas-powered-steam generating stations.

Yet that's only part of the efficiency story. The Bloom Energy Servers, commonly called Bloom Boxes, consume the methane at the site of the energy consumption, so there are no transmission-line losses. And since they consume natural gas, the Bloom Boxes release half as much carbon dioxide per kilowatt-hour as a coal-fired generator.

Part of the mystery surrounding the Bloom Box is how its fuel cell can withstand temperatures of up to 1800°F, which would cause many other types of fuel cells to break down or need maintenance. Bloom is not revealing that secret. And in terms of performance, according to the company, a single cell (one 100 × 100 mm metal-alloy plate between two ceramic layers) generates 25 W. Peak output from one Bloom Box full of these plates is 100 kW. Each Bloom Box costs $700,000.

FILLING A NICHE AT CYPRESS

The Bloom Boxes' role in the Smart Grid lies in distributed generation. In a typical industrial application, such as the Cypress facility in San Jose, the Bloom Boxes work in concert with rooftop solar panels in a grid-tied system that enables the company to sell surplus production back to the electricity supplier.

Overall, the current solar and fuel-cell installations provide only 75% of the Cypress plant's total electricity needs. But CEO T.J. Rodgers has said he wants to fill in the other 25% through new operating efficiencies and new technologies he hopes to have the opportunity to invest in. He's already on the boards of Bloom and SunPower, which supplied the solar panels.

In addition to Cypress, other large companies that have installed Bloom Boxes include Coca-Cola, Adobe, eBay, Google, FedEx, Bank of America, Wal-Mart, Safeway, and Kaiser Permanente (Fig. 1).

SILVER SPRING NETWORKS

Silver Spring Networks makes the communications hardware that goes into smart meters, but its communications reach extends far beyond the physical layer. It supplies "The Smart Energy Network," a two-way, IP-based (Internet protocol) communications link to every point on the grid. In the field, it's agnostic in terms of the medium, using 900 MHz, powerline communications (PLC), WiMAX, or whatever link a customer chooses (Fig. 2).

The physical network nodes can be installed on light or power poles or at the substation. In energy-supplier offices, Silver Spring network management software interfaces with existing back-office systems and connects them to the Smart Grid.

Rather than concentrate exclusively on remote meter reading or dynamic pricing, the company chooses to emphasize the Smart Grid's benefits in system monitoring in its customer outreach. Before the Smart Energy Network, repair services had to wait for a customer complaint before acting. Also, there was no way to determine the extent of the outage, nor was there a way to verify when all customers had their service restored.

But if powerline voltages vary outside of a set window, or if a fault brings down one consumer's or many consumers' electricity services, the Smart Energy Network reports the results to operations virtually instantly. This enables the intelligent dispatch of repair personnel and system monitoring as services are brought back online.

For the long term, Silver Spring has built in the hooks that will allow companies to advise customers of rate changes predicted or in real time, with the ability to provide that information on a display at the customer site or communicate it to a smart appliance that will automatically respond to price changes according to customer-entered presets. There are also hooks for monitoring or controlling such Smart Grid features as electric vehicle charging, distributed generation, distributed storage, pre-payment, and more.

This is not vaporware. Silver Spring has been engaged with electricity suppliers in many locales. A year-long project with Oklahoma Gas & Electric gave 2500 homeowners in the town of Norman, Okla., an array of home energy management devices, platforms, and pricing structures to evaluate. There were smart thermostats, home energy displays, and Web portals from Silver Spring, as well as a set of consumer programs from OG&E to test how customers reacted.

OG&E offered customers two types of programs: time-of-use pricing and variable peak pricing. Time-of-use pricing would change only a few times per day, though there was the possibility of a few "emergency" days when customers might be charged more than twice the usual price per kilowatt-hour.

Under variable peak pricing, homeowners might see more frequent pricing changes based on wholesale power markets. It could range from a base rate of 11.3 cents per kilowatt-hour at standard usage time, to 4.5 cents off-peak, to 23 cents and up for high-usage periods.

The results are still being assessed. But broadly, the experiment shows that it was possible to cut peak loads by up to 57%, and cut average, across-the-board energy use by up to 33%, over the course of a hot Oklahoma summer.

Silver Spring also is engaged in other tests with additional companies such as American Electric Power, Baltimore Gas & Electric, CitiPower & Powercor Australia, ComEd, Florida Power & Light, Guelph Hydro Inc., Indianapolis Power & Light Company, Jemena, Maui Smart Grid Project, Modesto Irrigation District, Pacific Gas and Electric Company, Pepco Holdings, Public Service Company of Oklahoma, Sacramento Municipal Utility District, and Western Power.

MAXIM INTEGRATED PRODUCTS

Like other companies in the linear/mixed-signal IC business, Maxim has the required expertise in capturing voltage and current data and digitizing it. What's unique about Maxim is its 2010 acquisition of Teridian, a long-term semiconductor participant in the electricity metering business.

This acquisition gave Maxim a leg up on metering technology, which it has extended beyond the home or business electric meter, plus the PLC part of the neighborhood-area network (NAN). In fact, PLC just received a boost with the approval of the IEEE P1901.2 standard for G3-PLC.

In addition, Maxim has moved its Teridian metering technology beyond the meter, leveraging it for broader control functionality. Last year, the company demonstrated metering-technology-based ac- and dc-power measurement capabilities adapted for high-power LED-lighting ballasts to provide metering and on-off control capabilities inside streetlights.

Today, depending on location, a municipality may pay the electricity supplier as much as $1000 per month for each streetlight based on a flat fee. With the switchover to LED streetlights, cities can take advantage of two interrelated Smart Grid features. One is simply the ease of monitoring that the PLC adds to the equation. The other is the ability to turn LEDs on and off easily.

If it can be done easily, there are obvious advantages in selectively turning streetlights off at night. For example, turning off every third streetlight in certain districts after a certain hour can produce a huge savings in a city's electric bill. If necessary, motion or body-heat sensing could be added to turn them back on. Perhaps it would also be desirable to provide fire trucks and police cars with an RF override device.

Something similar could be completed in public and private parking garages, again with motion sensing. This would even be a help with building security because a lights-on condition would alert guards to the presence of human beings.

One drawback to doing any of this in the past is that gas-discharge lamps, widely used for outdoor area lighting since the 1960s, have a complex turn-on process that discourages extinguishing them once they're on. In contrast, LEDs turn on and off instantly.

At the same time, the ability to accurately meter power consumption for each streetlight or garage-lighting fixture using Smart Grid technology would enable city managers and private garage owners to negotiate electricity rates based on actual use, rather than an arbitrary monthly usage fee. In addition, using something like Silver Spring's monitoring software, the city maintenance department or the private garage owner would have near-instantaneous information about outages.

Maxim demonstrated this capability at the Lightfair conference last May. The demo was based on the Teridian/Maxim 78M6613 energy-measurement system-on-a-chip (SoC) integrated in a ballast capable of measuring its own power efficiency. The demo ballast had both Digital Addressable Lighting Interface (DALI) and ZigBee controls.

According to Jay Cormier, Teridian/Maxim business manager for energy measurement and communications, the 78M6613 is the industry's first SoC energy-measurement solution for ac and dc power that enables the capture and reporting of real-time energy data. Measurement accuracy is ±0.5% over a 2000:1 dynamic range. The SoC itself includes tools, self-calibration, and ac-power diagnostics, including power, power factor, voltage current, voltage sag, and dip.

On the PLC side, Maxim participated in the development of the IEEE P1901.2 standard for G3-PLC, an orthogonal frequency-division multiplexing (OFDM) implementation that replaces the original frequency shift keying (FSK) version of PLC, while maintaining a carrier frequency below 500 kHz, which allows the signals to pass through transformers (see "G3-PLC Provides A Technology Platform For The Smart Grid," p. 44).

The new standard supports IPv6, and with OFDM, data rates of 300 kbits/s are possible. The MAX2992 modem pairs with the MAX2991 analog front end (AFE) to provide a complete PLC chipset for Smart Grid communications. Maxim partnered with ERDF (Electricité Réseau Distribution France) and major equipment manufacturers to define the specification and conduct field tests. The first deployment was to customers in France last summer.

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