Snow Melting & De Icing.pdf

GEothErmal

Snow mEltinG

and dE-iCinG

European

Geothermal

Energy

Council

Current Situation

Geothermal Solution

ing, the road users have normally

not adapted yet to the changed traf-

ic conditions. Bridges use to cool down earlier

than the normal roads. Thus icy surface condi-

tions can occur on bridges even when the nor-

mal roads don’t give any hints for problems.

w inter maintenance, snow melting

The safety of pedestrians, waiting or walking,

as well as the security of the running trafic

may be increased with a reliable, sustainable

and environmentally-friendly method.

Diligent winter maintenance is a crucial factor to

guarantee certain mobility on the roads. A irst

intervention of the winter maintenance vehicles

is needed on bridges, on strong inclines, on im-

portant trafic intersections, on express ways in

urban areas, etc. However, obstructions in traf-

ic due to snow and ice may also constrain the

use of maintenance and emergency vehicles.

Consequently the number and the length of the

hold-ups are increasing instead of decreasing.

This may even lead to a complete breakdown

of public and private trafic.

Different geothermal

sources are suitable.

Freezing rain in particular can stop trafic within

minutes – even in large urban areas. The trafic

comes to a halt – for hours. The maintenance

service is no longer able to clear the roads.

Geothermally heated outside surfaces are typi-

cally based on hydronic heat exchanger instal-

lations in the pavement. The installed heating

capacity depends on the climatic conditions and

the system speciications. Snow melting needs

higher system temperatures than simple pre-

vention of ice-formation. Low system tempera-

tures implicate an anticipatory operation control.

Also carports, ramps or car access ways to a

building need special attention during the cold

seasons. Snow and ice cause delays in profes-

sional work. Delayed lights due to snow and

ice at airports or on runways are annoying and

ex-pensive. Last but not least, sidewalks, pub-

lic areas, waiting areas for pedestrians need

to be cleared of snow and ice to prevent ac-

cidents during day and night time.

Various system designs are suitable. Various

sources may be used: Direct use with geother-

mal hot water (normally bound to special geo-

thermal conditions); direct use of warm or cold

groundwater; direct use of borehole heat ex-

changers or energy piles. A combination with a

heat pump may be considered. Underground

thermal energy storage (UTES) is suitable - in this

case the heated area is also cooled in summer.

Geothermal snow

melting and de-icing

is based on

hydronic systems.

A winterly trafic situation leads to reduced

speeds, trafic jams and therefore to losses of

time. Every improvement in the status quo has

a positive effect on the capacity and perform-

ance of roads, the trafic progresses and so our

society.

Other heat sources – like waste heat – may be

taken into account if a reliable supply over the

whole design lifetime is guaranteed.

The irst step in system design consists of the

deinition of the plant speciications – as accu-

rate as possible. The next step is an estimation

of the annual operating time and the typical and

maximum heat output of the heating system.

w ith the irst days of winter approach-

and de-icing ”from the bottom” us-

ing renewable and free geothermal

heat is an obvious solution.

Examples

measured

pavement temperature

a number of pilot plants for geothermal

snow melting and/or geothermal de-ic-

ing have been built all over the world.

-5

measured

air temperature

In the USA a few projects for geothermal road

and bridge heating have been realized. Some

of these are combined with heat pumps. Some

others are using seasonal heat storage. The

oldest documented geothermal snow melting

installation was built in 1948 using natural hot

geothermal water.

-10

October

November December

January

February

March

-10

Winter 1995/96

centric ield of 91 bore-hole heat exchangers.

In winter, heat is extracted from the heat stor-

age and used to maintain a temperature of the

bridge surface above 3 °C. SERSO provides a

direct use of the geothermal heat. Electricity is

only used for circulation pumps. The installation

has shown that much more heat was collected

in summer than needed in winter for de-icing.

Experts agree that cooling in summer would

also extend the lifetime of the pavement.

Prevention of

ice-formation on

a bridge surface

(Swiss SERSO

plant).

In the 1990s several pilot plants for snow melt-

ing installations based on geothermal heat

pumps were built in Japan, where active snow

melting using non-renewable sources has a

long tradition.

There are similar road and outside surface

heating systems for snow melting and de-icing

in other European countries (e.g. The Nether-

lands). These systems use mainly groundwa-

ter as heat and cool source and are combined

with building services.

Geothermal snow

melting installation

at a bridge in

Amarillo, TX (USA).

A well known and well documented geothermal

installation is the SERSO pilot plant in central

Switzerland, which went into operation in 1994

and is still running. Aim of the installation was

to prevent ice-formation on a highway bridge

surface.

Another such installation was constructed in

the Harz region in Germany in 2005. Aim of the

geothermal heating system was snow melting

on a platform of a local train stop. The platform

has an extent of 200 m. The underground heat

storage is tapped with 9 borehole heat ex-

changers with a length of 200 m each.

Geothermal snow melting and de-icing was

a subject of different studies recently worked

out in central Europe. The GeoVerSi study of

Nordrhein-Westfalen’s road construction and

maintenance department (Germany) serves

as a recent example.

SERSO is in a way the mother of the geo-

thermal bridge or road heating systems. The

SERSO system was developed and designed

in the early 1990s and went into operation in

1994. SERSO is working since 1994 without

interruption until today. Aim of the installation

was to guarantee the same road surface con-

ditions on the heated bridge as on the adjacent

road sections.

Infrared picture of

the Swiss SERSO

plant when

operating on the

left lane.

SERSO is collecting heat in summer from the

hot road surface and is storing the energy in a

near-by rock storage, which consists of a con-

advantages

Costs

surface heating is a feasible and ap-

proved possibility to increase traf-

ic and public safety. Several examples have

shown that geothermal road heating systems

work without problems over years – completely

renewable. A fully automatic operation allows

reducing the number of night shifts of winter

maintenance staff.

pump is very cheap in operation, in-

dependent of the geothermal heat

source used. The use of ground source heat

pumps makes the system operation more ex-

pensive.

The installation of a hydronic geothermal heat-

ing system is rather cost intense - depending

upon the geothermal heat source. The costs

range from several hundred Euros to about

1’200 Euros/m 2 .

A geothermal snow melting or de-icing sys-

tem is a smart and environmentally-friendly

alternative to the common mechanical and/or

chemical winter maintenance and is – as a big

advantage – available in the day and at night

without a costly stand-by emergency organisa-

tion.

A value beneit analysis is recommended and

normally shows a reasonable result. Although

the initial costs are high, such systems are not

uneconomical. Social and macroeconomic

beneits are given.

At heavy snow fall, the geothermal heating

prevents the freezing of the surface even with

low system temperatures: mechanical clearing

becomes very easy.

Geothermal snow melting on a small

access road to a private parking area.

Geothermal snow melting systems applied to

important trafic junctions or express ways in-

creases mobility as well as trafic safety. It de-

creases the number of accidents and the total

number of trafic hold-up hours and therefore

lowers the overall economic costs.

Basic data: Located in central Europe; heated

area: 25 m 2 ; cooling in summer provided; no

heat pump used; heat demand approx. 9 kW th

- depending on the local climatic conditions.

Geothermal snow melting system: 1 borehole

heat exchanger (depth 260 m - depending

on local geology). Costs of borehole heat

exchanger, piping and heating installation

in the pavement; control system and adjust-

ment: 855 Euro/m 2 . Electricity need per year

(operating costs) approx. 350 kWh.

Contact:

EGEC

European Geothermal Energy Council a.s.b.l.

Renewable energy House

Supported by

63-65 rue d’Arlon

B-1040 Brussels

t : + 322 400 10 24

F : + 322 400 10 10

w : www.egec.org

E : info@egec.org

The sole responsibility for the content of this publication lies with the authors. It does not necessarily relect the opinion of the European Communities.

The European Commission is not responsible for any use that may be made of the information contained therein.

Photo and graphical elements credits : EGEC, US DOT - Federal Highway Administration, NIRE – Japan, Polydynamics Engineering Zurich,

Arcadis Consult GmbH, Tiefbauamt des Kantons Bern. Published in September 2007 - Text : Walter J. Eugster.

Design: ACG Brussels. Printed on ecologically friendly paper (chlorine-free paper)

G eothermal road, bridge or outside

G eothermal snow melting without heat

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