overall efficiency. Currently serving more
than half of the university’s 5. 5 million sq
ft of property, the new systems lie two to
three miles apart and are not interconnected.
The university has a 10-year operation and
maintenance contract with Clarke Energy,
UK agents for the GE Jenbacher engines,
which undertakes all routine maintenance
and has engineers on 24-hour call to
respond to any engine problems.
Campus buildings not served by the
new energy centers are typically heated by
high-efficiency natural gas boilers, some
feeding a small group of buildings. A small
number of specialist laboratories, etc. are
cooled by electric chillers in the warmer
months.
Pollock Halls of Residence
Edinburgh’s first CHP project was the
2003 installation of a 526 k We GE
Jenbacher gas reciprocating engine to operate as the lead boiler serving the Pollock
Halls of Residence, home to more than
2,000 first-year undergraduates. Already in
place were three 2 MW dual-fuel (natural
gas and light oil) shell-and-tube boilers that
continue to provide top-up and standby
heating capacity. This system supplies heat
to 1,400 dormitory rooms in six houses
plus two administrative/refectory buildings
via an existing two-pipe low-temperature
hot water distribution system in walkway
ducts serving the north half of the site. The
new engine was simply lowered into the
lower level of the boilerhouse under the
refectory and connected in to provide a slipstream input on the site return main prior to
the existing boilers.
Since installation, the Pollock Halls
system has cut annual CO2 emissions by
450 tonnes and reduced noise nuisance in
an adjacent conference suite. The £ 1 million ($1.9 million) project was funded in
part through a £250,000 ($475,000) grant
from the Community Energy Programme
jointly managed by the Energy Saving
Trust and the Carbon Trust, established by
the U.K. government to help business and
the public sector reduce carbon emissions.
Courtesy University of Edinburgh.
St. Leonard’s Hall houses administration and function rooms at the university’s Pollock Halls of
Residence – site of the institution’s first combined heat and power installation.
King’s Buildings
Next, the University of Edinburgh
turned its attention to the 45-year-old
steam heating plant and distribution net-
work at its King’s Buildings campus, home
of the College of Science and Engineering.
The university considered four different
energy options for this project:
1. Close the existing central plant and
install individual boilers in each building: Expensive, intrusive and involved a
higher price for firm gas.
2. Strip out the existing central plant and
steam distribution system and install a
CHP system with new low-temperature
hot water distribution system: Lowest
life-cycle cost with only 5 percent standing heat losses versus 30 percent losses
from the old steam system.
3. Replace the existing central plant with
CHP, but retain the existing steam distribution system: Still inefficient with high heat
loses and problem of how to eventually
replace the aging distribution network.
4. Maintain business as usual, with only
replacement of steam boilers in years
five, six and seven: Stuck with energy-inefficient distribution system and constrained for future firing options; highest
life-cycle costs when taking into account
rising fuel prices.
The university chose option 2 – to
replace the old steam system with a new
CHP and piping system – as this option
provided the lowest whole life cost.
The entire former system – comprising
four boilers with combined capacity of more
than 80,000 lb/hr of steam, plus steam
pipes in walkway ducts – was stripped out
early in 2003 to make way for the CHP
technology, installed later the same year.
The new equipment includes a 2. 7 MWe gas
reciprocating engine and two 7. 5 MWth
Courtesy University of Edinburgh.
The university’s second CHP system, at its
King’s Buildings campus, supplies heating to
nearly 30 buildings including the Michael
Swann Building for biological sciences. Built in
1996, the building (shown here) was named
for Professor Michael Swann, under whose
academic leadership the university established
the first department of molecular biology in
Britian.
