Fuel Cells for Data Centers: Power Generation Inches From the Server Li Zhao, Jacob Brouwer National Fuel Cell Research Center University of California, Irvine {lz,jb}@apep.uci.edu Jie Liu, Sean James, John Siegler, Aman Kansal, Eric Peterson Microsoft, Redmond, WA {liuj,seanja,jsiegler,kansal, ericpete}@microsoft.com ABSTRACT Typically, improving data center availability requires designing in more infrastructure; the antithesis of reducing costs. Is there a way to cut infrastructure, cost and emissions while improving energy efficiency and server availability? We consider and evalu- ate the integration of fuel cells with IT hardware with various architectural designs, essentially col- lapsing the entire energy supply chain, from power plant to power supply unit, into the confines of a single server cabinet. In this paper, we propose a distributed power architecture for fuel cell pow- ered data centers to achieve high reliability and ef- ficiency. We experimentally validate the design and demonstrate the use of a 10kW Proton Exchange Membrane Fuel Cell (PEMFC) stack and system as the distributed power source to power a server rack, eliminating the power distribution system in the data center and the grid outside of the data cen- ter. The PEMFC is found to respond quickly and reproducibly to both AC and DC load changes di- rectly from the rack. By utilizing the fuel cell DC output, 53% energy efficiency in a single server rack can be achieved. We also carry out cost analysis to quantify the cost savings that could be achieved with fuel cells placed in each rack. We evaluate and characterize the performance and the dynamic load following capability of the fuel cell. In ad- dition, direct DC power from the fuel cell system eliminates the capital cost and operating conver- sion losses from systems that use energy storage Microsoft Research Technical Report MSR-TR-2014-37. . and AC/DC conversion equipment. Reducing com- ponents in the energy supply chain not only cuts cost but reduces points of maintenance and failure improving availability. 1. INTRODUCTION In the last decade, we have witnessed dramatic advances in data center design due to the demand of offering uninterrupted cloud and online services at lower expense. For example, in many designs, aggressive air-side economization (using outside air directly to cool servers) has replaced computer room air conditioning (CRAC) systems; evaporative cool- ing has replaced chillers; and power over-subcription is used to better utilize power capacity. As a re- sult, power utilization efficiency (PUE), defined by the ratio between overall facility power consumption and the power used by the servers, has improved from an industry average of 2 to the best practice of 1.11 in at least one news release [12]. However, the fundamental data center power infrastructure, consisting of transformers, power distribution units, UPS systems, and backup generators, has changed little. This power system is necessary to deal with the high-voltage AC power grid and its relatively low reliability at 99.9%. In this paper, we explore a drastically different design point for data center infrastructure by lever- aging the natural gas grid (or other locally avail- able bio-gas or hydrogen source) and fuel cell tech- nologies. Our analysis and experiments show that we can achieve low cost, low greenhouse gas emis- sion, high reliability, and high efficiency by using mid-sized fuel cells (producing a few kilowatts) at the rack level, directly supplying DC power to the servers, and effectively replacing the power distri- bution system in a data center by a gas distribution network. Fuel cells (FCs) convert energy from fuel (e.g., hy- drogen, natural gas, ethanol, or bio-gas) into elec-