energy and environment 1 dr. hassan arafat department of chem. eng. an-najah university...

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)

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

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

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

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

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

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

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

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)

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

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

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

17 Solar energy

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)

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

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

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

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

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

26 Wind energy

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

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

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.

32 Environmental impacts of wind power

33 Environmental impacts of wind power Facility operation Electromagnetic interferences Need of back-up Risk for birds ?

Estimated annual bird deaths in the Netherlands Source: European Commission1999

35 Environmental impacts of wind power Facility dismantling Waste materials

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

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

GHG Emissions Ground level ozone precursors Acid rain precursors Comparison between wind and conventional energy technologies Source: Mc Culloch, Raynolds, Laurie, 2000

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)

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

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

43 Potential causes of concern associated with geothermal energy Dismantling Construction materials Altered ecosystem and landscape

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

energy and environment 1 dr. hassan arafat department of chem. eng. an-najah university...

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