active in a different sector – farming.
In addition, he had to work hard
to persuade people to replace their
existing heating systems, most of which
were still functioning well. Skuk’s good
relationship and communication with
local residents enabled him to win their
support – and advance sales.
Franz Skuk’s greatest challenge
was to persuade potential
customers to switch to an
energy supplier originally from
a different sector – farming.
System construction started in
August 2002, and the boiler house
began supplying district heating service
to the first customers in February 2003.
System Description
The Bleiburg project is designed for
approximately 1,400 full load hours a
year, based on 229 heating days ( 3,360
heating degree days for Bleiburg).
Currently 70 percent of the potential
district heating customers in Bleiburg
are connected to the network. There are
110 buildings on the system, including
the Austrian Army and military barracks,
grade school, senior citizens’ home,
other community buildings and
individual homes.
The town has a theoretical
connection potential of 8 MW thermal,
with 6. 5 MWth connected today. Of
this, public buildings, commercial and
industrial customers account for around
5 MWth, with private households
accounting for the remainder, although
they have the most substations. The
total amount of heat sold is 7,500 MWh.
At baseload, the district heating
network operates with a 2 MW biomass
boiler (supplying 2. 4 MWth of heat) plus
the waste heat from three biodiesel
motors (producing 700 k W thermal
and 700 k W electrical energy in total).
The electricity is used to power a 3 MW
backup boiler and is also fed into the
national grid. (Skuk produces his own
biodiesel on his farm, using waste oil
and cooking fat.) There are two network
pumps, each with 22 k W output, 136
cu m/hr ( 35,927-gal/hr) pump output
and 39 m (128-ft) delivery head. During
summer months, only the 1. 5 k W pump
is used.
Tapping Local Resources
The Bleiburg system is fueled
with locally sourced wood chips, made
directly on site from scrap wood, and
uses waste heat generated by biodiesel
motors – creating a carbon-neutral sys-
tem. Since the network went into operation, a total of 9,538,200 metric tons
of carbon dioxide emissions have been
eliminated, and the town’s heating oil
use has been reduced by 770,000 liters
(more than 203,000 gal) annually.
Because Franz Skuk produces a
large proportion of the necessary raw
materials himself, in addition to obtaining them locally, long-term fuel supply
is guaranteed. In other similar projects, long-term contracts are entered
into with local suppliers in advance of
the project, or the suppliers acquire a
stake in the business themselves. These
measures help secure stable pricing. In
many cases, somewhat higher prices are
paid than in the normal marketplace
in order to make long-term supply
contracts possible. This provides many
forest managers with an attractive additional fixed income and strengthens
the local business cycle. It would make
no sense to import biomass from other
countries, as this would result in an
absurdly large carbon footprint.
Design Temperatures and
Cost-Effectiveness
For the Bleiburg system to be competitive, Skuk found that he needed to
limit his pumping/distribution costs by
maintaining a temperature differential
of at least 40 C (104 F). This must be
done through maximum capacity utilization and adaptation of the secondary
systems (hydraulic adjustment, with
maximum possible temperature spread
in the domestic system too); otherwise,
the cost-effectiveness of the entire system is at risk, as it will then be too large
and require too much electricity for
pumping.
Table 1 shows technical and financial data for an actual biomass district
heating network that is somewhat bigger than, but still comparable to, the
Bleiburg system. It has 19 km ( 12 miles)
of pipelines and a connected heating
output of 27 MWth. The network design
temperatures have a crucial bearing on
system success because they directly
relate to the size of the pipelines and
the necessary pumps. Table 1 illustrates
what happens to system cost-effectiveness when delta T is changed.
