Engineers propose nanogrids, smarter switches
Bruce Nordman, an energy analyst at Lawrence Berkeley Lab, called for engineers to define a new class of nanogrids using standard Ethernet Category 5 cables. The small grids could take several forms including an individual hut in a poor village that uses a solar panel or car battery to supply energy through its home and perhaps to its neighbor.
“If we could have an infrastructure where people can safely deliver power and manage it, we could do a lot to increase people’s quality of life,” Nordman told a gathering of about 100 Ethernet Alliance members. “Why not let Ethernet be the way to deliver it,” he said.
“Just as some people went from having no phone to having a cellphone, they may go directly to having distributed nanogrids, bypassing our legacy expensive central grids,” he said. “I am not proposing getting rid of the central grid, I just think it could be less crucial,” he added.
Nanogrids could use all direct current power and thus eliminate the need for energy wasting conversions. The concept could be applied in developed countries as well, linking rooftop solar panels on a home through gateways to home appliances.
The distributed grids would need ways to track, manage and pay for energy. Nordman said the IETF is developing EMan, a protocol for tracking and reporting power use over Ethernet that could become a foundation for nanogrid protocols.
“Really every notebook computer today is a nanogrid” because it provides power through USB to peripherals, he noted. “So we already make good use of nanogrids today, and we could make better use of them,” he said.
Ceiling lights connected to Cat 5 cables are also commercially available, he noted.
So far nanogrids are just a concept. “I’m just trying to sell the idea to get more people working on it,” Nordman said. “I’d like to show functioning demos putting together installations with different products—that would be a powerful next step,” he said.
Separately a Google engineer proposed ways to make network switches in a data center more power efficient. The systems are currently among the poorest data center devices in using power proportionally.
Today’s CPUs adjust across about 70 percent of their power range dynamically and still accomplish meaningful work, said Bob Felderman, a principal engineer in platform networking at Google.
By contrast, DRAMs operate over about 50 percent of their power range, hard drives only 25 percent and network switches as little as 15 percent. “The network stands out like a sore thumb,” said Felderman.
“We are looking not for on/off states, but lower power states where systems still get things done,” he said. “In our perfect universe, we’d like to slow down to 10 percent of the link speed and use 10 percent of the power,” he added.
Infiniband does relatively well here, scaling down as needed to fewer, slower links and saving power. “I’d love to see that with Ethernet,” he said.
He described a research paper that proposed a so-called Elastic Tree where networks can be remotely managed to consolidate traffic on fewer lines, shutting switches on and off as needed.
Currently, Google is experimenting with the OpenFlow technology initially developed at Stanford for software-defined networks
“We’re very actively working on OpenFlow control of our nets for traffic management,” he said. “The next step would be to leverage these capabilities for energy efficiency,” he added.
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