Transcript of Energy and Environment 1 Dr. Hassan Arafat Department of Chem. Eng. An-Najah University...
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- Energy and Environment 1 Dr. Hassan Arafat Department of Chem.
Eng. An-Najah University Environmental Impacts of Renewable
Energy-Part I (these slides were adopted, with modification, from
Ms. Paulina Bohdanowicz, KTH Institute, Sweden)
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- 6 Hydropower large dams World population of dams, by country
(total of 45000 in 2000) Source: WCD 2000 Average dam age 35 yrs;
2/3 in developing countries
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- Hydropower large dams Source: WCD 2000 Construction time
5-10yrs. 160-320 new large dams per year; ~1700 large dams under
construction in the past years
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- Potential causes of concern associated with hydroelectricity
construction phase IRREVERSIBLE ENVIRONMENTAL IMPACTS Local
pollution Modification of primary watersheds - radical change of
landscape (inundation of large areas, deflection of rivers,
creation of new infrastructure, loss of productive land/soils) - 20
th century dams flooded appr. 0.5 million km 2 of land area of
Spain Destruction of habitats - threat to flora and fauna
(extinction of some species, appearance of new species) - at least
20% of the worlds more than 9 000 fresh water fish species have
become extinct, threatened or endangered in recent years
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- Potential causes of concern associated with hydroelectricity
construction phase Resettlement of local inhabitants (political and
cultural conflicts, economic compensation) - large dams in 20 th
century 40-80 million people worldwide, 3 Gorges Dam alone 1
million) Loss of cultural/historical property Pressure on natural
resources Often unpredictable effects
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- Potential causes of concern associated with hydroelectricity
construction phase Chinas Three Gorges dam - the largest and the
most powerful dam in the world It will stretch 2 kilometers across
the Yangtze River, stand 185 meters high, and create a
600-kilometer lake behind it
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- 11 Potential causes of concern associated with hydroelectricity
- operation phase Risk of seismic activity In 1930, first case of
seismic activity related with impounding was realised in Mead
reservoir created by Boulder dam, USA 70 such induced seismic
effects have been known so far 5 Richter or more in scale 11
reservoirs 6 Richter or more in scale 4 reservoirs Temporary
phenomenon Risk of dam failure (20 th century world except China 10
000 people; China alone 1975 250 000 people) Source: Hydropower and
Environments: Present context and guidelines for future action, Vol
III, p.1-90
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- 12 Potential causes of concern associated with hydroelectricity
- operation phase Changes in river flow regime up and down stream
Deterioration of water quality - possible health risks (dumping of
municipal sewage and industrial waste, waterborne diseases in
stagnant waters) Loss of freshwater due to sedimentation An
estimated 0.51% of the total fresh water storage capacity of
existing dams is lost each year to sedimentation in both large and
small reservoirs worldwide. This means that 25% of the worlds
existing fresh water storage capacity may be lost in the next 25-
50 years in the absence of measures to control sedimentation. This
loss would mostly be in developing countries and regions, which
have higher sedimentation rates Source: Hydropower and
Environments: Present context and guidelines for future action, Vol
III, p.1-90
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- 13 Potential causes of concern associated with hydroelectricity
- operation phase Fish kills No direct benefits for local
communities, electricity usually transferred over long distances
Changes in local climate (large mass of stagnant water) Possible
emissions of methane (degradation of flora/organic matter in
stagnant water)
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- GHG emission from reservoirs The gross emissions from
reservoirs may account for between 1%-28% of the global warming
potential of GHG emissions Source: WCD 2000
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- 15 Potential causes of concern associated with hydroelectricity
- dismantling phase Local landscape never returns to the initial
state Major risk of inundation and destruction New change of
environmental conditions Disposal of the parts
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- 16 Positive environmental impacts of hydropower Virtually no CO
2 produced Little other effect on the atmosphere (little local
increase in water vapour, temperature effects, possible CH 4
emission) Negligible noise pollution Limited risk of explosion,
fire or emission of noxious chemicals Dam construction can prevent
flooding
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- 17 Solar energy
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- 20 Potential causes of concern associated with solar energy -
unit construction Use of toxic materials in manufacture of solar
thermal, PV cells & batteries (cadmium, arsenic, hydrogen
selenide gas) Production and transport of parts (energy)
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- 21 Potential causes of concern associated with solar energy
facility location Large scale systems only applicable to locations
with high solar irradiation and sun availablity Sequestration of
large land areas (when constructed as grid-connected central
station systems - 5 acres 0.02km 2 - of land per 1 MW of capacity)
1 acre = 4046.8m 2 1 hectare = 0.01 km 2
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- 22 Large scale solar-thermal The largest solar thermal-
electric installation of its kind in the world, the Luz project in
Californias Mojave Desert, has a peak output of some 350 MW and
occupies several km 2 of land Source: Godfrey et al, 2003
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- 23 Potential causes of concern associated with solar energy
facility location Visual intrusion in rural and urban environments
Need for cooling installation/cooling water cooling water - scarce
in regions where solar insolation is high (need for water
conservation) water use for solar thermal plants is similar to
amounts needed for a comparably sized coal or nuclear plants, but
depends on the type of cooling tower (wet, wet-dry, dry) Require
backup system - fossil back-up system and/ or thermal storage: a
fossil back-up system is needed in order to guarantee the
electrical power during times of low solar irradiance; thermal
storage systems reduce the amount of fossil fuel consumed
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- 24 Potential causes of concern associated with solar energy
facility operation fugitive losses of Heat Transfer Fluid the HTF
is a synthetic organic oil, which decomposes during operation;
light decomposition products are volatile and find their way out of
the system; proper maintenance of the installations minimizes
fugitive losses (losses can be reduced to 0.09 %/a of the total HTF
volume, which corresponds to 0.0043 g/kWhe) venting of light
decomposition product of HTF the light decomposition products of
the HTF have to be vented regularly (about 0.03 %/a of the total
HTF volume corresponding to 0.0016 g/kWhe); these can be captured
in a condenser HTF losses in case of losses of HTF the contaminated
soil has to be treated properly,e.g. in a bioremediation process;
in California, total HTF losses are in the order of 1 %
annually
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- 25 Positive environmental impacts of solar energy Low or no
emissions of gaseous or liquid pollutants (if operated properly)
Reduced impact on atmosphere No moving parts mechanically safe
General area of land used lower than in case of conventional plants
(in life cycle perspective) Job creation Energy independence and
security
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- 26 Wind energy
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- 29 Potential causes of concern associated with the wind power
Facility construction Production and transport of parts (energy)
Land use ( a modern wind farm uses only 1% of the land occupied and
the towers only 0.2%. ) The average wind farm requires 17 acres
(0.068 km 2 ) of land to produce one megawatt of electricity
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- 30 Wind farms This wind farm, at Carno in mid-Wales, is one of
the largest in Europe. It incorporates 56 wind turbines, each with
a rotor diameter of 44 metres and a tower height of 31.5 metres.
The total installed capacity is 33.6 MW, sufficient to provide
power for some 25 000 homes The Middelgrunden wind farm, completed
in 2001, is located in the sea just off Copenhagen harbour in
Denmark. It includes 20 two megawatt wind turbines, which provide
3% of the electricity consumption of the Copenhagen municipality
Source: Godfrey et al, 2003
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- 31 Potential causes of concern associated with the wind power
Facility operation Visual pollution (sensitive landscapes),
flickering Land erosion Noise (mechanical and electrical equipment;
aerodynamic) 200 meters away from a wind turbine a normal noise
level at wind speeds about 8m/s is 45 dBA Denmark: minimum distance
to households 200m Sweden: wind turbines are usually not placed
closer than 300-500 meter from nearest household.
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- 32 Environmental impacts of wind power
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- 33 Environmental impacts of wind power Facility operation
Electromagnetic interferences Need of back-up Risk for birds ?
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- Estimated annual bird deaths in the Netherlands Source:
European Commission1999
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- 35 Environmental impacts of wind power Facility dismantling
Waste materials
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- 36 Positive environmental impacts of wind power No release of
CO 2, acidic gases, particulates or radioactive pollutants When
wind exchanges fossil fuel savings are in the range of 11 800-18
000 tons CO 2 per year for a 5 MW wind farm (UK) Water or fuel
supplies not required Land can be utilised Job creation Reduced
dependency on conventional fuels
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- 37 Comparison between wind and conventional energy technologies
A case study from Alberta, Canada Wind power - a single 600kW wind
turbine producing 1.3 million kWh of electricity annually Alberta
Inter-connected System: Coal 89% Natural gas 8% Hydro electricity
3% Natural gas power Source: Mc Culloch, Raynolds, Laurie,
2000
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- GHG Emissions Ground level ozone precursors Acid rain
precursors Comparison between wind and conventional energy
technologies Source: Mc Culloch, Raynolds, Laurie, 2000
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- 40 Potential causes of concern associated with geothermal
energy Construction phase Drilling of wells, usually in wild,
naturally sensitive areas (noise; steam escaping while well
testing; disposal of chilling fluids; accidents)
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- 41 Potential causes of concern associated with geothermal
energy Operation phase Emissions (open vs. close loop system) CO 2,
H 2 S, HCl, HF, NH 3, CH 4, H 2 Solid wastes and noxios fumes
Brines/sluge (silica compounds, chlorides, arsenic, mercury,
nickel, and other toxic heavy metals, even radon) ground water
pollution Risk of land subsidence/induced seismicity Water confilct
due to the necessity of large amount for cooling Visual
pollution
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- 42 Emissions from coal and oil fired plants and geothermal
power plant Source: Environmental and Economic Impacts of
Geothermal Energy Geothermal Energy Programme website
http://www.eren.doe.gov/geothermal/geoimpacts.html as accessed
2002-03-24http://www.eren.doe.gov/geothermal/geoimpacts.html
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- 43 Potential causes of concern associated with geothermal
energy Dismantling Construction materials Altered ecosystem and
landscape
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- 44 Positive environmental impacts of geothermal power Exists
basically everywhere (low T, for the use through heat pumps) Net
positive effect on environment as compared with conventional plant
of the same power output Low (no) emissions Limited land required
for the plant itself Geothermal drilling safer than oil or gas
drilling (limited fire and explosion risk) Wide range of utilities
Independent of weather and climate