District
heating at Oslo airport, Norway
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The heating system for Oslo's new international airport at
Gardermoen is based on a district heating network relying on heat produced from
bioenergy. The system, installed by the company Gardermoen Fjernvarme (GFAS),
was built at the same time as the airport and its related infrastructure. The
airport opened to air traffic on 18th October 1998, but the heating system was
started up a year earlier and used during the construction of the new
buildings.
The initial planning of energy systems for Oslo's new
international airport began in the early 1990's. A parliamentary resolution
stated that the airport buildings should be as environmental friendly as
possible. The biofuel plant was the first large-scale plant to be used for only
district heating in Norway.
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The biofuel boiler has a total output
of 6 MW at 50 % fuel moisture. The flue-gas condenser provides
1.2 MW at 50 oC return temperature and 50 % fuel moisture
when the bioenergy unit is running at full output. In addition
to the bioenergy unit, three 8 MW oil-fired boilers have been
installed to help cover peak heating requirements and provide
spare capacity. Three electrical boilers were installed in
2000 with a total capacity of 3.6 MW.
Description
Financial resources / Economic Benefits
Results
 Energy
production
Environmental
Potential
for replication
Network
of promoters and parties involved
Contact
Description
The heating network is a 'standard' district heating system
designed to operate at 120 oC and 16 bars. It is particularly noteworthy that
the temperature in the network remains constant at 110 oC from October to May,
despite the fact that the airport's de-icing activity is based entirely on
district heating. The required water temperature for the de-icing activity is
100 oC. High return temperatures are avoided because all the buildings are
volume regulated and yield a low return temperature. For example, the best
building – an aircraft hangar – yields a return temperature of only 25 oC from
a supply temperature of 110 oC – a difference of 85 oC. This is highly
favourable because less pump work is required, the piping can be used more
efficiently and the condensation unit operates better.
The furnace is a traditional, moveable inclined grate.
Combustion fans and fuel feed controls allow optimum combustion with high
efficiency and low emissions. Preliminary measurements indicate oxygen (O2)
content in the flue gases of 3-4 % of the dry gas, which corresponds to an
efficiency rate close to 90 % when the flue gas temperature is below 150 oC.
Condensation plays a key role in the system, where flue gases
with a temperature of 65-70 oC are cooled so that the steam is condensed and
the heat is released. The hot condensate then contributes to heating the
incoming district heat.
Financial resources / Economic Benefits
The total investment cost of the district heating system and
heating plant was NOK 54,000,000 (€ 7,200,000) in 1998. During the first five
years of operation there was a further investment of approximate NOK 6,000,000
(€ 800,000).
| Capital investment in 1998
|
NOK mil.
|
€ Mil.
|
| Bioenergy unit, 6 MW |
10 |
1.3 |
| Oil-fired boilers 3x8 MW |
5 |
0.7 |
| Pipes, electricity, control system |
8 |
1.1 |
| Building, ground work |
12 |
1.6 |
| District heating and exchangers |
15 |
2.0
|
| Total |
50 |
6.7 |
| Investment fee |
4 |
0.5 |
| Subsidy from government |
-4 |
-0.5 |
| Total |
50 |
6.7 |
The tax on investment is 7 % of the total investment, which is
the same amount as the project has received in subsidy from the government.
The project was funded from share capital, a connection fee
from the largest consumers and borrowing (approximately 50 %). The borrowing
was complicated as investment companies are not used to working with projects
of this kind with a long pay back period and large outlay. The payback period
for the bioenergy unit has been calculated at about five years, compared with
oil firing, and the total project has a pay back period of 10 years.
Results
Energy production
The total heat delivered from the district heating system is
50-60 GWh a year.
The energy loss in the district-heating network is calculated
at about 4 GWh a year.
Annual maintenance and operating costs are estimated at NOK
3,000,000 (€ 400,000).
During an average year bark and wood chips will replace fuel
oil to produce about 35 GWh a year.
Environmental
By using wet biomass to meet the airport's heat requirements,
the energy stored in forestry residues is utilised, avoiding the use of 35
GWh/year of fuel oil. Sourcing the biomass locally minimises the environmental
impact of fuel transportation.
The emissions from the plant are quite low. The emissions of
dust, carbon monoxide (CO) and nitrogen oxides (NOx) are well below those
permitted by the authorities.
The environmental integration with the local landscape is very
good. The building is situated close to the main road carrying passengers to
and from the airport.
Potential for replication
After the Gardermoen plant was built a further 20-30 small
bioenergy plants (1-10 MW) have been built in Norway. Most of the plants use
lower moisture fuel and all of them use a different feeding system to transport
the fuel from the bunker to the furnace.
The potential for further development of similar project in
Norway is quite good.
Network of promoters and parties involved
Gardermoen Fjernvarme AS, a company owned by the local utility
Gjerma Energi and the utility Viken Energinett from Oslo was originally the
owner of the plant.
At the same time as the liberalisation of the electricity
marked the district heating company (Gardermoen Fjervarme AS) changed its name
to Fjervarme Ost AS and is now owned by Hafslund ASA.
Enercon was the project manager during construction period and
helped Gardermoen District heating with the feasibility study and the contracts
with the different contractors.
Petro Ett AS was the contractor for the complete bioenergy
plant. The company delivered the fuel transportation system, furnace, boiler,
exhaust cleaning equipment and the process control system.
In addition, Gardermoen Fjernvarme has had the following
contracts:
• Oil boilers from Peder Halvorsens
Kjelfabrikk, Norway
• Electric boilers from Varmeteknikk AS, Norway
• Distribution pumps from Processpumpar AB, Sweden
• Piping in the heat plant, Varmsvets Enterprenad AB, Sweden
• Building construction, Ragnar Evensen, Norway
Contacts
Owner
Fjernarme Ost AS
Henrik Ibsens vei 20, NO-2060 Gardermoen
Arild Dahlberg,
+47 63 97 84 45
fax: +47 63 97 84 47
arild.dahlberg@viken.no
Project manager during construction
Enercon AS
Hogdaveien 11, NO-1482 Nittedal
Mats Rosenberg
+47 67 07 05 94
fax: +47 67 07 51 06
enercon@online.no
Contractor
PETRO ETT AB
Helsingborgsvägen 33, SE-262 72 Ängelholm
Tommy Karlsson
+46 431 41 00 10
fax: +46 431 41 00 20
tommy@petroett.se
www.petroet.se
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