3/21/2012 | 4 MINUTE READ

Green Guide

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“Smart Outlet” Creates Electrical Grid Flexibility; Super Seaweed; The Power of Air


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Self-Monitoring “Smart Outlet” Creates Electrical Grid Flexibility

As electric vehicles (EVs) gain popularity, charging requirements will place increasing demands on electrical grids. For example, a standard household 120-volt outlet typically has a 15-amp circuit breaker, meaning the maximum amount of energy that an EV can consume is approximately 1,500 watts, or 1.5 kW per hour. Since a battery pack normally needs 12 to 15 kWh for a full recharge, it can take 10 to 12 hours for a full charge. Using a 240-volt outlet—such as those used for large appliances—an EV will receive 240 volts at 30 amps, or 6.6 kW per hour. Still requiring a charge time of about five hours. Either option equates to a lot of stress on a grid. To get the most of grid architecture, researchers at Sandia National Laboratories (sandia.gov) have developed a “smart outlet” that can independently measure, monitor, and control electrical loads with no connection to a centralized computer or system. It is designed to make the power grid more distributed and intelligent, capable of reconfiguring itself as conditions change.

Decentralizing power generation and controls allow the grid to evolve into a collection of microgrids, which can function individually or collectively as part of a hierarchy or other organized system. Outlet co-inventor Anthony Lentine explains: “A more distributed architecture can also be more reliable because it reduces the possibility of a single-point failure. Problems with parts of the system can be routed around or dropped on and off the larger grid system as the need arises.”

What’s more, the smart outlet can get better use out of less-predictable energy sources like wind and solar power because it can vary the load demand to compensate for variations in energy production.

“With the increased use of variable renewable resources, such as wind and solar, we need to develop new ways to manage the grid in the presence of a significant generation that can no longer supply arbitrary power on demand,” Lentine says. “The smart outlet is a small, localized approach to solving that problem.”

What Makes the Outlet “Smart”

The outlet includes four receptacles, each with voltage/current sensing; actuation (switching); a computer for implementing the controls; and an Ethernet bridge for communicating with other outlets and sending data to a collection computer. The outlet measures power usage and the direction of power flow, which is normally one-way, but could be bi-directional if something like a photovoltaic system is connected. Bi-directional monitoring and control allows each location with its own energy production to become an “energy island” when the main power grid goes down.

The outlet also measures real power and reactive power, which provides a more accurate measurement of the power potentially available to drive the loads, allowing the outlets to better adapt to changing energy needs and production.

If the outlet is successful, similar technology can be built into energy-intensive appliances like EVs and connected to a home-monitoring system, allowing the homeowner greater control of energy use.


^ Anthony Lentine is the co-inventor of the “smart outlet.” The experimental technology monitors and controls electrical loads without a connection to a centralized system.


Super Seaweed?

Sugarcane and corn, the mainstays of ethanol produc-tion, may have a new competitor in the biofuel world: seaweed.

Scientists at the Berkeley, CA-based Bio Architecture Lab (BAL; ba-lab.com) are engineering a genetically modified version of E. coli to extract the sugars in seaweed and convert them into renewable fuel. The modified microbe is powerful enough to digest alginate—the main complex starch found in brown seaweed—into smaller sugar compounds that it subsequently ferments into ethanol.

The researchers say they chose the underwater feedstock because of its low cost and fast growth. And unlike corn and sugarcane, seaweed doesn’t compete with food crops for land and water use. The researchers also say that fuel based on the material would emit less CO2 than corn-based ethanol.

Still in the research phase, BAL is operating four seaweed farms in Chile where they have had success in growing seaweed at economically viable production yields. The next step is studying the economic impact of using the algae to produce ethanol on a larger scale.


^ Scientists at the California-based Bio Architecture Lab have discovered a method to convert the sugars in seaweed, shown here during harvest, into a renewable fuel.
(Photo courtesy of Bio Architecture Lab)


The Power of Air

If researchers at IBM (ibm.com) are successful, lithium-air batteries (you read that correctly: air) will seriously extend the number of miles electric vehicles (EVs) can travel. Whereas EVs with lithium-ion batteries can generally go about 100 miles on a charge, IBM says its battery technology ups that to 500 miles.

The lithium-air batteries have energy densities more than 1,000 times greater than the ion variety. They use carbon cathodes (not metal oxides), which react with oxygen from the air to produce an electrical current. They are also said to be significantly lighter than those currently in use.

So why isn’t this super battery available now? IBM had a problem with the original automotive application, with chemical instability and frequent recharging taking a toll on a battery’s life. The good news is that the researchers say they’ve found alternative electrolyte compounds that will eliminate this problem. Their goal is to have a prototype ready by 2013, with commercial models on the market around 2020.