A 200 kWe trigeneration system based on a PAFC fuel cell has been operating successfully at a local government headquarters building in London for a year and a half. Here, John Lidderdale describes the installation, its several advantages over conventional energy supply systems, and its early operating experience.
Logan Energy has completed the installation and integration of a 200 kWe PAFC power module and associated cooling module at the Transport for London (TfL) Palestra Building in Southwark, London, UK. The fuel cell forms part of an integrated trigeneration system providing electrical energy, heat and cooling to the Palestra building. It is said to be the largest capacity fuel cell operating in London.
As part of its commitment to reduce energy consumption and greenhouse gas emissions TfL commissioned the project in 2008; at that time it estimated a reduction in carbon emissions of 40% and a cost saving of à‚£90,000 per annum as a result of the combined cooling, heat and power (CCHP) installation.
To communicate the benefits of hydrogen, and the fuel cell to people passing and visiting the building, a permanent multi-media exhibition display has been created – fuelled by the energy generated on site.
The state-of-the-art hydrogen fuel cell, funded by the à‚£25 million TfL Climate Change fund, provides electricity, heat and cooling to the building. In addition, the building’s hot water supply will be heated by the fuel cell. At times of peak energy use, the building will generate a quarter of its own power, rising to 100% at off-peak periods.
The waste heat from power generation will be pumped into a unit on the roof which will work to keep the building cool, and supplements the building’s six electric chillers.
Savings made from reduced energy bills in the next financial year will be reinvested to fund more energy saving projects. Once optimization of all the systems has been completed, full and complete data will be available to monitor the system performance.
|Fuel storage tank|
THE TRIGENERATION PROJECT
The fuel cell system has been installed into the pod area at ground floor level to the Blackfriars Road elevation of the building; offloading and positioning of the unit was undertaken at the weekend to avoid unnecessary disruption to traffic in the area.
The system is configured to operate in three modes:
- grid connect ” system is connected to the main building electrical distribution system
- idle ” the system is disconnected from all systems
- grid independent (island) ” the system is connected to one of the three uninterruptible power systems providing back up power to critical IT equipment.
As part of the integration the system has been fitted with independent metering to monitor not only electrical energy delivered to the building and gas consumption, but also any heat rejected by the system, providing a complete picture of the system performance.
A system of interconnecting insulated pipe work, and electrical cabling connects the fuel cell power module to existing systems to distribute heat and electricity to associated plant and equipment, including an absorption chiller, hot water storage system and the main electrical building distribution system.
The system is monitored by building maintenance staff using a remote serial communications link to a dedicated computer running the user interface software. All operating parameters are available to view, but alteration is restricted to authorized staff and engineers.
Coordination of the services installations required a multi-disciplined team of designers and installation engineers to ensure all the system interfaces were appropriate and fitted together seamlessly to create an optimized low carbon generation system.
The trigeneration system is capable of providing 200 kWe and approximately 263 kWth of energy to the building services installations, operating at a system efficiency of 36%. It is anticipated that this figure will reduce over the life of the equipment.
On completion of the installation the integrated systems were subjected to over 40 individual, witnessed, and monitored tests to ensure correct performance and operation. Once the optimization phase is finished, complete system monitoring will begin and all results will be published in future display energy certificates to be issued by TfL. Ongoing optimization of the systems will continue and system monitoring and performance will be undertaken through the coming year to ensure complete annual operating and seasonal cycles are included within the recorded data.
|Figure 1: A schematic diagram shows the fuel cell leading the energy supply process|
When compared to grid-produced coal-fired electrical energy an overall reduction in energy use of approximately 40% is anticipated. This will be confirmed when all systems are monitored, including all the heat generating circuits.
The fuel cell has been integrated into the buildings’ fire detection system and is configured to disconnect from the building network in the event of a fire on all floors except the ground and basement levels. In the event of a detection of fire at these two levels the system will shut down completely.
Emissions from the fuel cell system are significantly less than traditional generation processes, and NOx levels less than 1 ppmV and carbon monoxide levels below 2 ppmV are expected. All other emissions of SOx, particulates and non-methane hydrocarbons are negligible.
THE COMPLETE SYSTEM
The fuel cell acts as the principal electrical source and principal boiler, and is ‘always on’. In the normal mode it runs as a base load unit providing the first 200 kWe to the building load. The approximately 130 kW of low grade heat (63à‚°C) goes to the thermal store for the building and the approximately 130 kW of high grade heat at 142à‚°C goes to an absorption chiller that provides cooling for one of the data centres within the envelope.
The fuel cell package contains a reformer that extracts a hydrogen rich reformate stream from natural gas and supplies it to the fuel cell stack, the majority of the remainder is carbon monoxide and carbon dioxide. The carbon monoxide is either used internally to provide the steam for the steam reformation process, or converted to carbon dioxide and discharged with the rest to atmosphere. The inherent efficiency of an electro-chemical process over a mechanical one is such that carbon reductions around 40% can be achieved against a conventional, non-CHP installation where electrons come from the grid and heat comes from mains-fed boilers.
Figure 1 shows how the fuel cell leads the supply process for the building, both for electrical and thermal demand. The system also includes a 700 kWe internal combustion engine CHP unit, 2 LV transformers, 2 HV supplies and a standby generator.
Installed in the pod area ” one fuel cell trigeneration unit
Since commissioning in February 2009 the installation has run without incident. There has been one occasion when the power supply to the building failed and the fuel cell reacted exactly as programmed. Having detected the browning of the grid, the fuel cell switched from grid parallel to grid independent mode, the UPS panel we supply disconnected from the building distribution system and the fuel cell adopted load following. When the grid was re-established the local panel re-connected and the fuel cell switched back to base load, 200 kWe mode.
This installation is the first:
- combined cooling heat and power fuel cell installation in the UK
- phosphoric acid fuel cell installation in London
- fuel cell to provide essential power, ie prime power plus automatic changeover to provide power on grid failure.
- reduced emissions ” NOx, SOx and carbon dioxide
- quiet operation, less than 40 db at 3 m
- higher efficiency of operation fuel-to-electricity than an engine driven equivalent, between 34 and 40% electrical
- utilizing heat output can increase operating efficiency to 80 ” 87%
- reduced energy costs
- modularity: 200 kW up to 2.4 MW
- low maintenance
- stable quality electrical power
- reliability of operation.
John Lidderdale is the managing director of Logan Energy Limited, Edinburgh, Scotland, UK.
Logan Energy Ltd is a UK-based expert in energy solutions harnessing the power of hydrogen. Being independent of both manufacturer and technology enables the company to provide impartial advice on today’s hydrogen technology, offering an alternative energy option.
Passionate about hydrogen and with an unparalleled history in fuel cells, Logan Energy in Europe does not limit itself to the application of fuel cells but all technologies that either generate or utilize hydrogen.
Logan Energy Corporation is headquartered in Atlanta, Georgia, US and has been providing clean, quiet and reliable fuel cell solutions to commerce and industry since 1994. Logan has been responsible for the installation of over 130 fuel cell solutions and presently operates 25% of the global installations, equating to about 18% of the global capacity.
Logan Energy exists to provide fuel cell solutions against a growing demand in the UK and throughout Europe for clean, quiet, efficient and reliable energy schemes which can run on carbon free fuels or use hydrocarbon based fuels more efficiently than any other technology and thus significantly reduce carbon emissions.