PALESTRA – FUEL CELL CHP TRIGENERATION

Background

The London Energy Strategy identified the implementation of fuel cell combined heat and power (CHP) as part of a ‘show by doing’ approach to stimulating low and zero carbon technologies in London. The development and implementation of fuel cell CHP was included in the London Climate Change Agency’s (LCCA’s) business plan and a feasibility study was undertaken by the LCCA to determine its practical implementation in Palestra. The study also included other options that could be combined with the fuel cell CHP project to maximise the reduction in CO2 emissions at Palestra.

The Hydrogen Fuel Cell

The hydrogen fuel cell is not only a British invention but more specifically, a London invention. The principle of hydrogen fuel cells was first demonstrated to the London Institution by British scientist and judge Sir William Grove in 1839. He discovered a relatively straightforward electro-chemical process where hydrogen and oxygen interact within a cell to generate electricity and heat.

 How a Fuel Works

The fuel cell contains an anode and a cathode with an electrolyte sandwiched between them, separating the two. Hydrogen is supplied into the anode and oxygen into the cathode. The two gases want to join but are prevented from doing so by the electrolyte which causes the hydrogen to split into a proton and an electron. The proton passes freely through the electrolyte whilst the electron is forced to take a different route around it, creating an electric current before re-combining with the proton to make hydrogen again and combining with oxygen through a catalyst, creating a molecule of water.

There are several different types of fuel cell that work on this principle, each using a different material for the electrolyte (alkaline, phosphoric acid, molten carbonate, solid oxide and solid polymer or proton exchange membrane). Each operates at different temperature ranges and is suitable for different applications within stationary or portable power, or transport. The hydrogen fuel cell proposed to be used on the Palestra – Fuel Cell CHP Trigeneration project is a phosphoric acid fuel cell.

UTC Power Phosphoric Fuel Cell CHP

Since Grove’s experiments, the technology has been developed intermittently facing opposition from the prevailing Hydrocarbon Economy, and it was not until the 1960’s space programme that fuel cells were used in a real practical environment. UTC Power (who also make the alkaline fuel cells for the NASA Space Programme) produced the first commercial stationary phosphoric acid fuel cells in 1991. See www.utcfuelcells.com .

More recently other manufacturers have produced demonstration fuel cells for the emerging residential CHP and transport markets but the UTC phosphoric acid fuel cell CHP is the only commercially available stationary fuel cell with UTC having installed over 260 fuel cell power plants in 19 countries on 5 continents. The UTC stationary fuel cell fleet has delivered over 1.1 billion kWh of energy worldwide but there is only one fuel cell CHP in the UK, the Woking Park – Fuel Cell CHP Trigeneration project, developed and implemented by the London Climate Change Agency’s Chief Executive Officer when at Woking. The Palestra – Fuel Cell CHP Trigeneration project will be the first fuel cell CHP system in London.

Please see downloadable pdf

Woking Park - Fuel Cell Combined Heat and Power System: US Department of Energy Project Report

Plant Description

The Palestra system will utilise a UTC Power Pure Cell 200 fuel cell CHP unit. The Palestra fuel cell will operate using phosphoric acid as the electrolyte, natural gas chemically reformed into hydrogen gas by steam reforming and oxygen extracted directly from outside air. The Pure Cell 200 can also operate on biogas, waste gas from sewage treatment, or other biogases. Biogases are rich in hydrogen and the Pure Cell 200 can be provided with a dual fuel option (biogas and natural gas) to ensure continuity of supply at full power and to take advantage of renewable gases in the future.

 
 

UTC Power Pure Cell 200 Fuel Cell CHP Operation

The UTC Power Pure Cell 200 Fuel Cell CHP is a packaged system combining the fuel processor (or reformer), fuel cell stack and power conditioner. The fuel cell stack comprises 32 sub-stacks of 8 fuel cells so the fuel cell CHP actually comprises 256 fuel cells. Heat is recovered at each sub-stack and aggregated to provide the fuel cell package heat output.

Project Description

The fuel cell project comprises a 200kWe fuel cell CHP, together with heat fired absorption cooling which will turn the fuel cell CHP system into a trigeneration system providing combined cooling, heating and power (CCHP). The project was originally conceived by the LCCA and included in the LCCA’s business plan to supply cooling, heating and power, which together with the renewable energy system installed at Palestra by the LCCA was originally intended to supply virtually all of the energy needs of the floors occupied by the LDA and the LCCA.                        

From the outset the feasibility study provided for two parts:-

(i) Fuel cell CHP trigeneration to supply CCHP to the floors occupied by the LDA and the LCCA.

(ii) Conventional or reciprocating engine CHP with additional heat fired absorption cooling and thermal storage to supply CCHP to the remaining floors of Palestra.

Since the start of the feasibility study it was announced that Transport for London (TfL) Street Management will be occupying the remainder and the larger part of Palestra. TfL is now the head lessee of Palestra and the LDA/LCCA are their tenants. Following the announcement it was decided that the project would be implemented as part of TfL’s fit-out contract managed by TfL Group Property and Facilities with the LCCA working in conjunction with TfL on the options for delivering the project.

The fuel cell CHP proposal is based on a high grade heat option that splits the thermal energy output into 50% high grade and 50% low grade heat. With this option it is possible to provide high grade heat to the heating and heat fired absorption cooling and low grade heat to the hot water system.

The second part of the LCCA study looked at three different CHP systems and the potential for extending the decentralised energy network to other nearby buildings. It also looked at the potential for recovering the water generated by the fuel cell for use in Palestra similar to the application for the Woking Park – Fuel Cell CHP project. If water recovery is able to be implemented this would turn the fuel cell CHP system into a quadgeneration system providing cooling, heating, power and 100% pure water to Palestra.

Project Implementation

The heat fired absorption chiller has already been installed on the roof of Palestra and the Fuel cell CHP is due to be delivered in July 2008. The conventional CHP is due to be installed late summer 2008 and the thermal store is due to be installed in December 2008. Individual plant will be commissioned when they are installed with the complete trigeneration package expected to be operational by February 2009.

 

Allan Jones MBE
Chief Executive Officer    
30 June 2008