What if the small data centers peppered throughout universities and small corporations could be powered by solar energy?
What if by using solar, the tech industry could significantly cut the carbon emissions attributed to small data center use?
These are the questions Rutgers researchers are attempting to answer. At an event at the end of April 2012, the university officially opened its solar-powered micro data center, called Parasol, which looks a bit like a metal frame with 16 solar panels on top enclosing a metal shack. The entire thing has been plunked onto the roof of the Piscataway campus’s engineering building.
The solar panels provide energy and shade the container from the sun. The container hosts two racks of energy-efficient servers (up to 160 of them) and networking equipment.
The system monitors the temperature and energy consumption of all components, turning off devices not in use. Parasol is wired into the grid and can draw on conventional power if solar is not available and storage batteries are exhausted.
Rutgers has funded the hardware for the project. In addition, $420,000 has come from the National Science Foundation (NSF), part of a total of $1.5 million in NSF grants that Ricardo Bianchini, the professor of computer science who is project codirector with Prof. Thu Nguyen, has received.
Before the NSF money arrived, the project had “support from Google for the general idea of having energy-efficient data centers that can both sense your environment and decide how to compute, based on what the environment is like,” Michael Pazzani, vice president for research and economic development at Rutgers, said.
Bianchini said climate change is directly related to the CO2 emissions released into the atmosphere. It turns out the information and communications technology industry has a very large carbon footprint, about the same as that of the entire aviation industry. What’s worse, that footprint is expected to double by 2020.
The tech industry indirectly increases CO2 emissions because most electricity in this country and around the world is generated by burning coal or natural gas, which are very carbon-intensive.
“The vast majority of electricity consumption [by data centers] actually comes from small and medium data centers,” Bianchini continued.
Bianchini said there are two approaches to attacking the emissions problem. Data centers can be colocated with renewable energy sources, like a large solar array, wind farm or hydro plant, or they can self-generate part of their electricity usage. For small data centers, the cost and the space requirements of solar and wind are manageable.
However, wind and solar are unique because when the wind is not blowing and the sun is not shining, you don’t have electricity unless you can figure out a way to store it, Bianchini added. “Your workload may not match the availability of energy … There are points where I have workload but no energy, and points where I have energy and no workload to run it.”
Bianchini is doing research on matching energy demand to supply. “You can play tricks in terms of delaying computations, degrading computations, adjusting duty cycles,” and so on, to try to match the two. “We can also do a follow-the-renewables type of computing, where we can move workloads from data center to data center, to wherever there are renewables available.” The setup will also allow the university to study trade-offs, such as using batteries or restoring electricity to the grid.
Rutgers is building the software necessary to maximize using green energy in Parasol. The first two software systems, dubbed GreenSlot and GreenHadoop, assume there are no batteries and brown energy should only be consumed when green energy is not available.
A new system called GreenNebula, an extension of the OpenNebula cloud manager, will be “aware” of the green energy available at the data center and maximize its use by migrating virtual machines across green data centers. It will also let Rutgers share Parasol with researchers from other institutions.
Parasol will be the hardware laboratory that allows Rutgers to do this research for real, not with simulators as it did in the past. It will also enable the university to explore hot research areas in data center study, such as energy-efficient free cooling: the idea that outside air can be used to cool the machines without a compressor or chiller. “This is the reason Parasol is on the roof. It allows us to study free cooling without the interference of a central air conditioner,” Bianchini said.
Another area of study is so-called “wimpy servers,” very energy-efficient servers that “look more like your laptop than a big-time mainframe. … We want to look at the types of workloads that are good for these kinds of energy-efficient servers,” Bianchini said.