The Department of Energy and Utilities has been involved in a number of substantial projects that are now closed.
Installation of the ICC’s Photovoltaic Array (1984)
Intercultural Center’s 300kW Photovoltaic Rooftop Array
The photovoltaic array at Georgetown University was installed in the summer of 1984 and turned on September of that year. The array spans almost 36,000 square feet of active area on the roof of the seven-storied Intercultural Center (ICC) that lies in the heart of campus. At the time, it was the largest rooftop array of its kind. It is made up of ten sub-arrays, which are distributed on the four south facing planes sloped at 35 degrees. They form a weather-tight roof for the ICC. The system was designed to produce 300 kW under standard test conditions of 1,000 watts per square meter (W/m2) at 28° C.
The basic unit of the array, a module, is an approximately 2′ x 4′ panel of 72 polycrystalline cells arranged in two parallel paths of 36 series cells each. In case of an open circuit failure of a cell, each group of 12 series cells is provided with a bypass diode. Eighteen panels are connected in series to form either a positive or negative half string with respect to a direct current neutral connection. A bipolar string from the positive to negative terminal generated about 512 volts direct current. There are a total of 4,464 panels in the array, providing 124 bipolar strings distributed among the ten sub-arrays. Sub-array nine had the highest generation capability with 16 parallel strings, while sub-array three had the least with 9 parallel strings. Each string is rated to contribute about 4.8 amps to the direct current generation. The inverter system or power conditioner operated above 95% efficiency in producing three phase 480/277 volt alternating current power to the building. The unit operated when there was enough sunlight to generate a threshold of about 5 kW.
From December 1985 to October 1986, the system was out of service to allow for enhancement of the lightening protection and to increase the general safety of operations. With that exception, the system operated regularly with only infrequent and brief (less than a day) outages, usually a result of the built-in protection features which activated to shut the system off. The unit turned itself on when there was sufficient light for stable parallel operation and then off once below this threshold. The early years saw as high as 300 kW peak generation and about 360,000 kWh per year. Deterioration of panels from within coupled with an accumulation of baked grime on the surfaces saw the production drop to just less than 200 kW peak and 250,000 kWh annually. The surface of the array was scrubbed in late 1993 and production recovered to about 240 kW peak and 300,000 kWh per year. Due to both aging and a reduced number of functional cells, the array’s production declined to about 160 kW peak and 100,000 kWh per year in 2007. Repairs returned the array’s yearly capacity to approximately 200,000 kWh, yet from July 2009 to June 2010, the system produced only 164,300 kWh and peaked at 160 kW. Over the years maintenance costs grew and efficiency waned, so, in December of 2011, seven years after its projected death, the photovoltaic array was shut down. The next step is to dismantle and replace it, but that would require substantial effort and funding. For now it rests quietly on the roof of the ICC, a stark symbol of Georgetown’s commitment to sustainability and renewable power. All in all, the photovoltaic array was a relatively trouble-free and hands-off generation system, which used no fuel and produced no pollution. From installation to shutdown, the array generated a total of 5.8 million kWh.
One of Georgetown University’s Fuel Cell Buses (Generation II)
Fuel Cell Bus Program (Advanced Vehicle Development Team)
The Georgetown University Fuel Cell Bus Program began in 1983 and was concluded in 2011. A fuel cell bus is an all-electric hybrid bus powered by a combination of a fuel cell and batteries. The fuel cell, which replaces the gasoline or diesel engine in a typical hybrid vehicle, generates electricity through chemical reaction fueled by oxygen and hydrogen. Using hydrogen and oxygen generates no pollutants as only water is the by-product of the process. The hydrogen for the fuel cell can be stored on the vehicle in canisters or generated on demand through extraction from another fuel type (e.g., methanol). Methanol, also called wood alcohol, is rich in hydrogen which makes it a good fuel source for a fuel cell system. It is a liquid which simplifies refueling.
Georgetown had three generations of fuel cell bus development projects, all supported by grants and contracts from the Federal Transit Administration (FTA) and the U.S. Department of Energy (DOE), with supporting funds from other interested federal agencies.. Five methanol-fueled fuel cell buses were built which proved efficient and quiet and functioned with near zero emissions.
In 1983, Georgetown managed a feasibility study conducted by Los Alamos National Lab and sponsored by the U.S. Department of Transportation (DOT) that concluded transit buses were ideal vehicles for fuel cell power. As a result, two 25 kW phosphoric acid-fuel cell (PAFC) systems (fuel cells are characterized by the type of catalyst used) and low temperature steam reformers for methanol were developed to prove fuel cell systems could power a 30foot transit bus.
In 1991, Georgetown was awarded contracts to build three methanol-powered fuel cell hybrid electric 30foot buses (Generation I). The first bus rolled out on Earth Day 1994, and the remaining two in 1995. Each bus was outfitted with a 50 kW PAFC.
Georgetown University was awarded a grant by the FTA in 1994 to build two larger (40ft) fuel cell buses (Generation II). The buses were Nova Bus models, popular in the mid1990s. BAE Systems provided the hybrid electric drive system. The first bus had a 100 kW PAFC fuel cell from United Technology Corporation and started running in 1998. The second bus, sent out in 2001, had a 100 kW Proton Exchange Membrane (PEM) fuel cell provided by XCellSys, a German fuel cell company.
In 2005, development began on a third generation methanol fuel cell system with the limited funding remaining on the grant. Georgetown awarded contracts to the Electric Power Research Institute and two German companies, the Center for Solar and Hydrogen Research (ZSW) and NuCellSys (formerly XCellSys). The team developed a fuel cell system and an onboard methanol reformer that was much smaller and lighter. While the previous system weighed around 4,000 pounds, this system weighed less than 1,000. It was packaged to fit the same space a diesel engine on a standard transit bus would, making it about a sixth of the volume of the previous system. Testing of the new system was successful, though some technical issues remained when funding ran out in 2011. The system was left in place at ZSW’s test laboratory in Germany. In September 2011, Georgetown submitted a final report on the history and the state of the technology of the methanol fuel cell bus project.