A California University campus has added a fuel cell cogeneration plant to its existing solar and microturbine-based on-site energy systems. And, as Andy Skok reports, the university uses all the outputs from the fuel cell plant to supply heating, power, cooling, irrigation and even carbon dioxide to stimulate plant growth.

Students and staff at California State University Northridge (CSUN) have been building green energy solutions for much of the past fifteen years. This university is making a measurable impact on its surroundings while continuously increasing its commitment to clean, distributed power. And an ultra-clean fuel cell is now providing the next logical step.

CSUN recently installed a 1 MW system comprising four DFC300MA power plants produced by Fuel Cell Energy, Inc., creating the world’s largest university-based fuel cell installation. The fuel cell plant is the latest addition to its showcase of alternative energy commitments, which includes solar panels, thermal energy storage and a high-tech greenhouse. Not only does the fuel cell allow the academic study of these efforts, it demonstrates the current commercial state-of-the-art by reducing reliance on the electrical grid, saving money and providing clean, quiet, 24/7 efficiency. Using readily available natural gas as its source fuel, it provides its power without combustion. Hydrogen is reformed from natural gas and used to power the plant, resulting in utility grade power and usable heat energy.

California State University’s 1 MW fuel cell installation provides approximately 18% of total campus power needs
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Because of their high operating temperatures, carbonate fuel cells are an excellent source of excess heat energy, which can be used for local heating and cooling needs. In addition to meeting 18% of the university’s baseload electrical requirements, the fuel cell’s cogeneration process provides cooling, space heating and hot water for several buildings.

The university is making maximum use of the fuel cell’s additional by-products – CO2 and water. The biology department plans to use some of the CO2 for carbon enrichment testing, and a ‘Subtropical Rainforest’ microclimate environment where CO2 and condensed water will be channeled into a Free Air Carbon Enrichment System, helping plants grow faster and providing partial carbon sequestration in the process.

A history of innovative solutions

Located on 356 acres (144 hectares) in the heart of the San Fernando Valley, CSUN has over 35,000 students, and is one of the largest and fastest growing schools in California’s 23-campus state university system. Ever-increasing demands for new power have led to ever-more-innovative solutions by CSUN staff, students and distributed energy firms.

In true California style, natural disaster has also helped to shape decisions at the university. The 1994 Northridge earthquake, which caused a great deal of damage to the campus, provided an opportunity to implement much-needed improvements. Tom Brown, executive director of physical plant management at CSUN, began an innovative energy-efficiency programme, designed in conjunction with a new central power plant.

Thermal storage

To complement the heating plant, three electric centrifugal chillers were installed. These generate chilled water at 39°F (4°C) during off-peak night-time hours, at much lower electrical rates. The chilled water is stored in a 2.3-million-gallon storage tank, then used for cooling during peak daytime hours, typically between 1 pm and 5 pm. This allows the chillers to be shut down during the part of the day when peak electric load is reached, and when higher rates would be paid.

The chillers are a good example of the explosive growth at CSUN. When the tank was originally installed, a single cold-water filling met cooling needs for several days. That same tank is now usually depleted during four peak hours each day. So in an effort to accommodate newly planned buildings, two new high-efficiency chillers will be added to help CSUN keep pace with burgeoning demand for additional cooling.

A new chiller for the Biology Science building will start construction soon, while one for the Performance Arts building is being designed and will start construction within the next few years.

Cogeneration with microturbines

CSUN’s first cogeneration effort was the addition of six natural gas-fired 30 kW Capstone microturbines. These were provided by the National Fuel Cell Research Center (NFCRC) at the University of California-Irvine, under a grant from the South Coast Air Quality Management District (SCAQMD). Under the agreement, NFCRC arranged for the installation and subsequent test of the microturbines’ performance. CSUN volunteered to be the host site, to pay for the fuel and to maintain the equipment.

Operation began in December of 2001, and was monitored by NFCRC from May 2002 to December 2004. Running continuously between 10 am and 8 pm, these units perform effective peak shaving, and currently provide 3% of all electrical needs at the CSUN. All recovered waste heat is used to provide hot water across the campus system.

According to SCAQMD, capacity and load factors were variable in 2002, but began achieving stability in 2003. By 2004, each microturbine was operating at capacity and load factors between 74% and 85%, and reliably producing between 10,000 and 19,300 kWh each month.

Solar photovoltaic

CSUN then added solar photovoltaic (PV) capability in two steps. In each case, the solar collectors were located in parking lots and designed to double as daytime shade providers for parked cars. And in each case, a team of student engineers helped to complete the installation. Working together, the two solar systems supply 2% of all electricity used on campus.

The first system was completed in 2003 and provides 225 kW of capacity, using pre-wired 75-W solar panels from Shell Solar. Although the total cost was an estimated US $2 million, Los Angeles Department of Water and Power (LADWP) and Southern California Gas Co. provided a total of $1.7 million in incentives.

Using more densely configured 165-W Sharp solar PV panels, the second project, completed in 2005, produces more than twice as much power – 467 kW – from a similar ground area. This project came in at $3.4 million, with $2.3 million being provided in incentives from the same two utilities. For the second installation, CSUN engineers provided a chance for students to see the PV process in action. A large glass window within the structure allows viewing of the solar collector’s operation, and displays figures for the amount of electricity being generated by sunshine.

Finally, fuel cells

Student growth from increased enrolments, and the resulting demand for more power, has outstripped even CSUN’s innovative energy efforts. Studies commissioned by the university suggested that its central power plant, just nine years old, was already reaching peak cooling capacity and could not support further expansion. New buildings would require their own heating and cooling capacity. A new distributed generation solution, particularly one with compelling cogeneration capabilities, seemed an obvious alternative.

The new power plant, comprised of four DFC300MA natural gas-fired fuel cells, has been operating since February of 2007, and supplies 18% of the campus electricity needs. (Combined, the four distributed energy systems provide 23% of all campus electricity.) Fuel Cell Energy provides operation and maintenance, and also trained the CSUN personnel. CSUN staff and engineering students not only wrote the specifications, they also constructed the plant – all in just one year.

Although the total estimated cost of the fuel cell power plant is $5.3 million, some $3.2 million will be recovered in state and utility company incentives. Total projected cost savings, taking into account building design, maintenance and chiller operation, will amount to $14.5 million over the power plant’s 25 year life cycle.

Green in more ways than one

One of the main reasons for such incentive-based savings is the new plant’s reduced carbon footprint and significantly reduced pollution levels. Because fuel cells make their energy without combustion, they produce virtually zero emissions of nitrogen oxides (NOx), sulphur oxides (SOx), or particulate matter. Many states, including California, consider them as a form of renewable energy that can qualify for state grants and other incentives.

As part of California’s Self-Generation Incentive Program (SGIP), Southern California Gas Company awarded CSUN $2.25 million in incentive funding, and the Los Angeles Department of Water and Power (LADWP) provided a $500,000 rebate. When the new chiller system is operational, LADWP will provide an additional $336,000.

Flexibility in building design and construction is a key factor for this type of power. Project savings, when compared with costs to support individual building systems and when combined with the new chiller plant now under construction, are estimated to be $65,000 in annual campus maintenance and $235,000 in annual energy costs. There will also be a $7 million reduction in future capital construction costs and total estimated life-cycle savings of $14.5 million.

To accommodate flexible siting, DFC fuel cell power plants are modular in design, containing separately configured units for DC power, electrical balance of plant, heat recovery/oxidant supply, and fuel and water treatment. Each module is arranged on its own skid to provide efficient transport to the installation site and ease of access for future plant maintenance. And because it runs quietly as well as cleanly (a DFC 300 kW fuel cell produces a noise level of just 72 decibels at a mere 3 metres of distance) the fuel cell at CSUN can be located in the heart of the campus.

Chilling out with CHP

Long established as efficient generators of heat using CHP, carbonate fuel cells can be just as effective at addressing cooling needs in warmer-climate applications – see Figure 1. CSUN’s fuel cell plant is at the heart of an efficiency cycle of electrical generation, thermal recovery, and chilled water distribution. The fuel cell plant will provide electric power to two 1000-ton chillers, built in a satellite chiller plant directly beside the fuel cell stacks. With an electric efficiency of 47%, the fuel cells already surpass microturbines and other engine technologies. Adding an efficient CHP process tapped into the plant’s exhaust stream, overall efficiency is increased to an estimated 83%.

Figure 1. Combined heat and power from a fuel cell system
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CSUN’s physical plant staff helped design and construct the barometric thermal trap used to recover the multiple waste heat streams, which exit the heat recovery unit at temperatures between 650°F and 750°F (343°C–399°C). Once combined and drawn through the trap, the waste heat enters the first-stage heat-recovery coil, transfers most of its heat, and drops to 170°F (77°C). Currently used to heat campus buildings, this first stage heat will also provide thermal power for the new chiller system.

A separate loop will be constructed to process second stage heat, which will pass over a latent heat-recovery coil, exit at 140°F (60°C), and be piped to the nearby student union to heat domestic hot water and a swimming pool.

CO2 to go

Although most of the carbon dioxide reductions from the system are a result of the fuel cells’ non-combustion process and overall high efficiency, the exhaust stream still contains CO2. At CSUN, this CO2 is put to good use in a sustainable development project.

After passing through the latent heat-recovery coil, exhaust heat still containing CO2 is directed into a recovery chamber and then exits to the atmosphere. As part of CSUN’s carbon-dioxide-enrichment research programme, a new distribution system is being built to collect side-stream flows of condensate from the recovery chamber and direct them to a greenhouse. There, the carbon-rich condensate will be used to boost plant growth.

This will form the basis for the university’s Subtropical Rain Forest, where a condensate diffusion system will help to create an artificial subtropical climate for basic education and research. And another valuable fuel cell by-product – water – will be used to irrigate the rain forest. Large plastic cooling towers, fuelled by the new chillers, will provide moisture for production of the rainforest plants.

Thus the new system provides an educational resource for students from biology to bioengineering. While budding botanists are studying photosynthesis, students from the College of Science and Mathematics can help estimate a fuel cell’s carbon dioxide enrichment potential within that same controlled environment.

But perhaps the biggest point of interest is for the engineering candidates – the fuel cell itself. Says Robert Ryan, a faculty member in CSUN’s College of Engineering & Computer Science: ‘Having a state-of-the-art fuel cell plant right here on campus is a unique research opportunity for our mechanical and electrical engineering faculty, and an extraordinary opportunity for us to mentor our student engineers.’

Part of the campus, part of the solution

Thus the DFC power plant rounds out a series of solutions – for distributed power and environment friendliness – while maintaining a low profile within the CSUN community. In addition to providing high-value electricity independent of an unreliable grid, each of the ‘by-products’ produced by the DFC300MA – heat, water, both hot and cold, and even carbon dioxide – are put to use providing value for faculty and students. Add in the education that the fuel cell technology provides for both amateurs and professionals, and this investment should continue to pay dividends far into a cleaner, more efficient future.

Andy Skok is Executive Director of Strategic Marketing, FuelCell Energy, Inc., Danbury, Connecticut, US.
e-mail: askok@fce.com