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Waste in, data out: Microsoft's closed-loop data centre experiment aims to change the impact of the world's IT sector.

MICROSOFT recently announced a small clean-tech project that could upend the growing environmental impact of the global information technology sector. The personal computing giant is investing $5.5-million to research, develop and build a 200-kilowatt data centre powered by renewable biogas energy from a wastewater treatment plant.

Located at the Dry Creek Water Reclamation Facility in Cheyenne, Wyoming, the data plant pilot project will function by passing biogas through a highly efficient molten carbonate fuel cell that converts methane and carbon dioxide into electricity. Microsoft claims that their system will reduce emissions by productively using greenhouse gases that would otherwise be flared off by the wastewater plant. The fuel cell will also produce less CO., per unit of power compared to the grid and reuse waste heat to save additional energy.

The hope is that this project will become a model for converting larger data centres--which typically occupy 100,000 [ft.sup.2] and can consume as much energy as 25,000 houses--from carbon-intensive to clean-powered. Microsoft and other tech giants currently rely on coal for half of their data centre energy demands, 80 per cent of which are for operating and cooling servers and other storage and networking equipment. Data centres alone consume up to two per cent of global electricity supply; their total usage jumped by 63 per cent to 38 gigawatts (GW) from 2011 to 2012, and is expected to rise again to 43 GW in 2013.

"The necessity for clean, renewable, reliable and low-cost power will increase exponentially in the near future," wrote Microsoft's Christian Belady on the company's blog. "Without a bold shift in strategy, our entire industry will become more dependent on a costly, antiquated and constricted power grid."

How Waste is Converted Into Energy

BIOGAS IS A COMBUSTIBLE gaseous fuel comprised mainly of methane, which is also found in other fossil fuels. To create biogas, microbes use high temperatures to degrade and anaerobically digest organic matter such as wastewater sludge, landfill, plant materials and manure.

At the pilot project's wastewater treatment plant in Wyoming, microorganisms break down sewage sludge from households and businesses. This produces biogas made up of methane (C[H.sub.4]), CO and small quantities of hydrogen sulfide ([H.sub.2]S), as well as moisture and siloxanes.

The [H.sub.2]S and siloxanes are filtered out using--activated carbon and a biotrickling filter, and moisture is condensed and drained back into the treatment plant.

A molten carbonate fuel cell (provided by FuelCell Energy Inc.) converts the biogas into electricity through a series of reactions. To support these reactions, the fuel cell consists of an anode, cathode and electrolyte, much like a battery.

In the initial reforming stage, the C[H.sub.4] in biogas combines with water to produce hydrogen gas ([H.sub.2]) and C[O.sub.2]. The [H.sub.2] is fed into the anode while the C[O.sub.2] is fed into the cathode. The cathode receives oxygen from outside and reacts with the C[O.sub.2] to produce carbonate ions (C[0.sub.3.sup.2]), which are transferred to the anode. Inside the anode, the [H.sub.2] and C[0.sub.3.sup.2]combine to produce electricity (8e-).

The electrochemical reaction in the fuel cell is considered clean compared to traditional internal combustion technologies because it does not produce carcinogenic diesel particulate matter (DPM) and emits very low quantities of nitrogen oxide (NOx) and sulfur oxide (SOx) into the atmosphere.

The two main by-products of the fuel cell's electrolytic process are high-quality C[O.sub.2] and water vapour, which can be reused for industrial applications such as fire extinguishers and pressured gas.

The other by-product, heat, is fed back to anaerobic digesters to provide the ideal environment for micro-organisms.

The electricity produced by the fuel cell powers the modular data centre. The data centre uses the electricity to power the computing needs of homes and businesses, effectively closing the loop. Unused electricity from the data center is returned back to the wastewater treatment facility to offset their electricity cost.
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Publication:Alternatives Journal
Date:May 1, 2013
Words:681
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