Prof.T.Shivaji
Rao,
Director,
Centre for Environmental Studies,
Gitam
University, Visakhapatnam
Cloud seeding operations have been
successfully conducted by about 40 countries during different periods during
the last 50 years. Recently Australia has taken up cloud seeding operations
in Snowy Mountains region to augment annual precipitation not only to obtain
more snow cover for improving the tourist trade but also for hydropower
generation and food production, besides using this technology to fight the
emerging impacts of the global warming. China has been extensively using
cloud seeding operations by employing more than 35000 people to fight the
disastrous consequences of the recurring droughts and also to reduce the
summer temperatures and thereby cut down electrical power for air
conditioning. Indonesia is conducting cloud seeding operations to store
additional water supplies in reservoirs for subsequent use during years of
water scarcity and drought. Cloud seeding is used in several places in
Russian and American states to eliminate the recurring fog conditions that
cause serious traffic disruptions in Airports and major urban settlements.
Many countries are extensively using cloud seeding to make drastic reductions
in the damages caused to lives and properties due to recurring hail.
Presently scientists are considering the revival of cloud seeding experiments
to tame the cyclones and thereby mitigate the damage caused by cyclones and
hurricanes. Thailand is regularly conducting cloud seeding operations every
year to obtain about 2000 mm of annual rainfall not only to meet the
municipal, industrial and agricultural needs but also to promote large scale
tourist trade by promoting environmental assets like good landscapes,
gardens, forests and wild life. In a few places cloud seeding is used to
fight the forest fires and to prevent unwanted rainfalls that are likely to
disturb the organization of scheduled international celebrations, games and
sports.
Cloud
seeding is cheaper for water supply than conventional irrigation: A brief review of some of the case studies on cloud
seeding experiments conducted in different countries to achieve increased
rainfall for municipal water supply, hydropower generation and agricultural
production at the cheapest cost are presented here. For more details refer to
the relevant websites cited. Further the costs of water supply from various
other sources are very high as compared to cloud seeding, which can be seen
from the following table-1.
Is
artificial rainwater 150 times cheaper than ground water …?
Sandy Land Underground Water
Conservation District (SLUWCD) has been working day and night in the
interests of the farmers to encourage food production to promote the state
economy and for this purpose have chosen the most effective method of
increasing the water availability by large scale tapping of the sky water and
they have succeeded because of their sincere efforts and close rapport
between their scientific and technological experts, administrators and the
general public. The target area includes Yoakum, Terry and Gaines county
regions in West Texas. http://www.sandylandwater.com/cost_benefit.htm
SOAR (Southern Ogallala Aquifer
Rainfall) Programme, Texas cloud seeding project covered 5.048 million acres
during the operational seasons covering 77 clouds in 2002 and 69 clouds in
2003. Yoakum county for its 5 lakh acres coverage shared the operational
costs estimated at $20,000. Two independent reputed weather consultant
agencies evaluated the cloud seeding project results. 63 out of 69 clouds
seeded during 2003 season produced rainfall increase of about 2,50,000 ac.ft.
For the 77 clouds seeded during 2002 season each cloud system produced
additional rainfall upto about 5000 Kton making a total increased rainfall of
3,80,000 Kton or 3,06,740 ac.ft. (One Acre feet =1234 Cubic meters)
However the economics of cloud
seeding have been estimated for Yoakum county.
1. Cost
benefit ratio for Yoakum county for 2002
a) Yield per acre of the total
SOAR project area for 2002 =
(3,06,740
ac.ft) ÷ 5048000acres = 0.06 ac.ft per acre
b) Proportion of excess water for
Yoakum county for 2002 =
(0.06
ac.ft/acre) X (511808 acres) = 31,100 ac.ft.
c) Cost per acre ft = ($20,000) ÷ (31,100
ac.ft) = $0.64 /ac.ft.
2. Cost
benefit ratio for Yoakum county for 2003
d) Yield per acre of the total
SOAR project area for 2003 =
(248500
ac.ft) ÷ 5048000acres = 0.05 ac.ft per acre
e) Proportion of excess water for
Yoakum county for 2003 =
(0.05
ac.ft/acre) X (511808 acres) = 25,194 ac.ft.
f) Cost per acre ft = ($20,000) ÷ (25,194
ac.ft) = $0.80 /ac.ft.
The above costs for Yoakum county
for 2002-2003 represent the purchasing cost of additional water produced by
cloud seeding. But the farmers are normally spending $120 per acre foot in
pumping costs from underground water wells. So if we compare the costs of
pumping incurred by the farmers with the cost of about $0.80 for cloud
seeding operation, the cost benefit ratio comes to 1:150. This clearly shows
that for every dollar spent by the farmer in Yoakum county the benefits
obtained will be 150 times higher.
Hydro-electricity
at cheaper cost :
Tasmania produces
most inexpensive hydro-electricity: Tasmanian
Hydro-Electric Commission is convinced of the economic success of the
Tasmanian experiments. This is perhaps best illustrated by the
decision of the Hydroelectric Corporation (HEC) to undertake the Tasmania II
experiment without any operational assistance from CSIRO. However, the HEC
has retained a very pragmatic approach to cloud seeding. McBoyle (1980)
quoting from Watson (1976) states “Cloud seeding has emerged as a feasible
and economic proposition in Tasmania when the increase in precipitation can
be utilized for power generation”. Currently Searle (1994) estimates that
each HEC cloud seeding operation costs $645,000 to run and returned an
average 55 mm of extra rain during each 6 months experimental season. When
the extra water in storage is priced against the energy generated by the only
HEC thermal station the real profit from the silver iodide seeding comes to
about $14.5 million per annum (Searle, pers. comm.) Seeding of these cloud
systems resulted in a 37% increase in rainfall. Suitable days occurred 18
times a year during the experiment and this gave rise to an estimated total
increase of 197 mm for seeded days.
Cost-benefit analyses carried out
by the Tasmanian Hydro-Electric Commission for the Tasmanian I experiment
suggest that the increased rainfall from seeding represents a gain of 13:1.
More recently Searle (1994) argues that the three separate cloud seeding
projects sponsored
by the Hydro-Electricity
Commission of Tasmania spanning 14 years have confirmed that cloud seeding
can routinely enhance runoff into Tasmanian storages by 10-20%. Searle
estimates that the energy gained by the cloud seeding operation costs less
than 0.2 US cents per kilowatt hour.http://www.dar.csiro.au/publications/cloud.htm#pt2
Gautemala : The Gautemala cloud
seeding evaluation was based upon monthly precipitation data for the period
1980 to 1989. The calculated 17 percent increase for the chosen month of 1992
June precipitation over the Chixoy drainage of Gautimala was equivalent to
1.81 inches. The Chixoy drainage is approximately 2,140 square miles or
1,369,837 acres. INDE officials indicated that the Chixoy watershed converts
precipitation to runoff with an efficiency of approximately 30 percent. The
additional June stream flow into Chixoy as a result of the cloud seeding
program can be estimated as follows:
1,369,837
acres x 1.81 inches = 206,617 acre-feet.
With the 30 percent efficiency
factor applied, this equals to 61,985 acre-feet (76,427,505 cubic meters).
The cost of this program can be pro-rated to estimate the program costs for
June 1992. This cost is $79,700 (U.S.). Consequently, the estimated cost of
the additional runoff is $1.29 (U.S.) per acre-foot or $0.001 (U.S.) per
cubic meter.
Honduras : Cloud seeding was conducted over the El Cajon and
Lake Yojoa drainage basins in Honduras during 1993, 1994, 1995 and 1997 rainy
seasons, to augment natural precipitation in these drainages, which will then
augment the amount of inflow into the El Cajon Reservoir. This extra water
can then be released to generate additional hydro-electric power. Evaluations
of the 1993, 1994 and 1995 cloud seeding programs indicated a 9 to 15 percent
increase in precipitation
attributed to the cloud seeding.
The June through October 1995
program indicated a 13 percent increase. Additional runoff was estimated as
366,876,000m3. Calculations of the cost of the program versus the value of
the additional inflow from the 1995 program were performed using certain
assumptions. The resultant benefit to cost ratio was calculated to be 23 ½
:1. http://www.nawcinc.com/cseng.PDF
Inexpensive agriculture and
drought mitigation :
China uses cloud seeding for
several purposes: The ground precipitation enhancement operations in Feng
Huang County of Hunan province during 1975-77 showed an increase of 55% of
the daily rainfall by statistics. Experiments in rainy season (April to June)
during 1975-86 using rockets in Fujian province showed rainfall increase by
24% with significant level of 0.05.
A group of scientists from the
Chinese Academy of Sciences concluded after recently doing research in the
province that exploiting water resources in the air could be a sustainable
way to solve water scarcity in North China. Based on the advice of the
scientists, the provincial government of Shanxi has made a six-year plan to develop
weather modification technologies, mainly seeding clouds to increase
precipitation. The province will strive to increase its annual rainfall by 2
to 3 billion cu m a year. Shanxi is among one of the most arid provinces in
China, with about 4 million people and nearly 1 million head of livestock
being affected every year.
Dry weather also leads to reduced
grain harvest, local officials said. Since the late 1980s, Shanxi
has been seeding clouds to
increase precipitation by 600 million to 800 million cu m a year.
According to Qin Dahe of China
Meteorological Administration (CMA) cloud seeding operations were conducted
from 1995 to 2003 in 23 provinces by using 42321 flights of aircraft with a
total flight time of 9881 hours and employed artillery and rockets. The cloud
seeding operations covered 30 lakh sq.km and precipitation was 2100 billion
cu.m (73,500 TMC). During 2003 alone 3,800 rocket launchers, 7000 anti
aircraft guns and many aeroplanes were used in about 1800 counties and
employed 35,000 people for the operations. About 413 Yuan (US$49million) were
spent for the operations.
According to Zhang Qiang a noted
Beijing official, in the first half of 2004, the meteorologists injected
silver iodide particles into the clouds to augment rainfall or snowfall over
Beijing Aeroplanes, rockets, artillery shells, meteorological balloons and
mountain top based generators were employed. From January to end of June
(Beijing Time report dt.24-7-2004) China used 227 aircraft putting in 530
hours of flight time in cloud seeding operations in 15 provinces and regions
covering an area of about 1.66 million square km and sprinkled chemicals into
the clouds by using 12,464 rockets and 66,000 large caliber artillery shells
in different provinces and cities producing 10 billion cubic meters (350 TMC)
of water. Zhang Qiang estimated that the cost of 1 cu.m of man made rain works
out to 2 US cents (equivalent to one Indian rupee).
According to Hu Zhijin a cloud
expert with Chinese Academy of Sciences Cloud seeding is cheaper than other
methods used by Government to solve the water shortage problem such as the
South-North water diversion project intended to transport water from Yangtze
river basin to Beijing and Northern parts of China. He said that for one dry
season about 2 to 3 million Yuan (US $ 24,180 to $ 36,270) was needed to
carry out the cloud seeding programmes.
Pakistan : Qamar-uz-Zaman Chaudhry, Director-General of the
Pakistan Meteorological Department (PMD), said that the department was
conducting cloud seeding experiments in the country with the assistance of
the Army Aviation, which was called artificial rain, though it was somewhat
misleading. However, he said, these experiments met with considerable
success. He said that PMD initiated the experiments from June 2000 to augment
rainfall mainly over drought hit areas of the country. He lamented that at
this experimental stage, besides the limitations of resources
(equipments, specially equipped aircraft etc) the main reason for limited
success in winter was that very weak weather systems were approaching
Pakistan. Most of these clouds were lacking the moisture content or these
were high clouds it could be developed to a level where drought situations
could be averted, he added. He said that among the three experiments -one in
Murree area and two in Baluchistan - could achieve some success in the form
of rain/snow.
The President of Pakistan, General
Musharaff proved his statesmanship as a savior of the people and the
environmental assets of Pakistan by directing the Heads of the Pakistan
Meteorological Department and the Aviation Department to fight against the
recurring droughts by conducting experiments on cloud seeding to promote
annual precipitation to augment substantially the snow fall and the rainfall.
Pakistan had made a success of the cloud seeding experiments. Out of the 48
warm cloud experiments conducted 30 were highly successful, 14 had a limited
success and 4 failed due to technical problems with the aircraft. Out of the
23 cold cloud seeding experiments 9 were highly successful, 6 had limited
success and 8 have failed.
Wyoming: On March 19,2002 the Governor’s Drought Management Task
Force met in Cheyenne to discuss and evaluate Wyoming’s conditions and
drought outlook. During the meeting it was stated that Municipalities,
agricultural interests, hydro-electric companies and others that would
benefit from additional snow pack that would help cover the costs. Jeri
Trebelcock with the Popo Agie Conservation District said the cost of cloud seeding
equates to $1 per
acre-foot.
Nevada: Benefits vary with the seasonal frequency of
suitable weather opportunities. Research results have documented
precipitation rate increases of 0.1 - 1.5 millimeters per hour due to ground-based
seeding during proper weather conditions. Estimates of augmented water from
seeding have varied from 20,000 to 80,000 acre-feet over each of the last ten
years. Seasonal percentage increase estimates have varied from 4 to 10%;
generally greater in drought years; less in above normal years. The cost of
augmented water, based on the cost of the program,has ranged from $7 to about
$18 per acre-foot. http://cloudseeding.dri.edu/Program/Synopsis.html
Kansas: Brian Vulgamore, who conducted Kansas-State’s
study, said “Unfortunately, science was unable to separate fact from fiction
after that, due to lack of research funding in the 1980s and ’90s.” That’s
why his study bypassed the science of modifying the weather. Instead,
Vulgamore tried to assess real-life impacts. He examined both rainfall and
hail in western Kansas and worked to put their outcomes in dollar terms. “The
smallest drought causes economic harm in any semi-arid farming region,”
Kastens pointed out. “Up to a point, extra rainfall brings extra economic
benefits.” But equal precipitation losses and gains don’t bring equal
results. Vulgamore’s analyses suggest that an added inch of growing-season
rain in western Kansas translates into an economic gain of about $18 million.
A 1-inch loss in rainfall translates into economic losses exceeding $19
million.
North
Dakota: Sell and Leistritz (1998)
studied the economic impacts of cloud seeding in North
Dakota. Eight of North Dakota’s
most common crops like wheat, barley, sunflower, soybeans, dry edible beans,
corn grain, oats, and flax were evaluated for impacts of a statewide cloud
seeding program. Results were based on a 45 percent reduction in crop losses
(Smith, et al.,1997), and a 15 percent increase in rainfall (Changnon and
Huff, 1972). The annual crop production increase was $34.4 million for hail
reduction and $52.2 million for rainfall enhancement statewide.
This $86.6 million direct impact
results in an increase in total business activity of $267 million or an
average of $14.52 per planted acre. Additionally, the estimated $3.2 million
annual cost of operating a cloud seeding program statewide is more than
offset by the $5.1 million in increased tax revenues. Thus, the program more
than pays for itself. Additional benefits to other crops, livestock and
reduction of property damage were not included in this report, but are also
thought to be substantial. http://www.swc.state.nd.us/arb/graphics/QandA.pdf
California: The cost of the annual cloud seeding program is
shared among the County and the water districts, which receive a benefit from
it. The cost is well justified when compared to its benefits. The average
cost of water produced by cloud seeding is less than $100 per acre-foot. By
comparison, the cost of State Water on the South Coast is roughly $1200 per
acre-foot. Desalinated seawater costs approximately $1950 per acre-foot.
Groundwater and water from Lake Cachuma average between $75 and $250 per
acre-foot. Cloud seeding is one of the least expensive sources of water.
(Santa Barbara County,USA).
Municipal
water supplies at cheaper cost :
UTAH cloud
seeding program: The
estimated average annual increase in runoff due to cloud seeding in Utah is 249,600
acre-feet. This is an average annual increase of 13.0 percent. The estimated
project cost for the 1999-2000 season is $254,300. The resulting cost per
acre-foot is about one dollar ($1.02).http://water.utah.gov/cloudseeding/PDF/Utcsprog.pdf.
Syria : Cloud-seeding technology is generally an expensive
process, dependent on its efficiency and effectiveness. The equipment used in
Jordan included C-B and VRC 74 weather radars, and an aircraft equipped with
meteorological recording instruments. The aircraft also contained a computer,
satellite station (METEOSAT NOAA), qualified radar technicians, engineers,
meteorologists and pilots. In Syria, the cloud-seeding project was initiated
in 1992, involving similar equipment and staff. Six aircraft were used for seeding
purposes during 1993-1994, with the project costs reaching 156 million Syrian
lira. The operation costs reached 25 million Syrian lira (US$ 0.5 million) in
1998. The costs per cubic meter of water for the years 1991-1997 were
previously highlighted. Based on the regression method used to estimate the
increased rainfall, the costs range between US 0.026-0.181 cents/m3 of water,
and between US 0.016-0.113 cent/m3
if the ratio method is used.
UNEP
Programme: It is estimated that
the cost of water produced is about $1.50/m3/season/ha (United Nations,
1985). This cost is made up of scientific equipment and hardware costs;
flying costs for cloud seeding (capital and operational, including
maintenance or hire charges); salaries for scientists and pilots; the cost of
seeding agents and flares; and, software costs (for experimental and monitoring
purposes).
South
Africa: Studies by the hydrological
community have projected a ~25% increase in annual
run off in typical Highveld
catchments if the annual rainfall could be increased by 7%. If attainable,
this will result in additional water at about 1/5 the cost of the cheapest
alternative in South Africa.http://metsys.weathersa.co.za/cloud_detail.htm
Experiments
on warm clouds by IITM, Pune (1973-1986) : The
Indian Institute of Tropical Meteorology, Pune launched a warm cloud seeding
experiment using aircraft in the semi-arid region towards East of Pune on the
leeward side of the Western ghats from 1973 to 1986. A randomized double area
crossover design with a buffer zone was used for the aerial seeding work. The
experimental area covering 4800 sq. km. was divided into 3 parts designated
as North, Buffer and South sectors in Ahmadnagar, Baramati area (Hindu dated
18-1-1988). The results of experiments on aerial seeding of warm clouds with
common salt and soap stone powder for the eleven years. (Refer Warm Cloud Seeding
Chapter)
Cost
Benefit Ratio For Warm Cloud Seeding : The
cost-benefit Ratio for the warm cloud seeding experiment based upon the data
collected by the Institute at Pune for the increase in precipitation
of about 20% works out as follows:
i) Total cost of the experiment
during the past Rs.58.0 lakhs
11 monsoon
seasons (Aircraft changes and cost of seeding material)
ii) Expenditure incurred during
1986 Rs. 8.0 lakhs
iii) Cost benefit ratio for a 20%
increase in rainfall due to seeding.
Average rainfall in the
experimental area during monsoon – 346 mm
Volume of water produced by
artificial rain during one monsoon season
Target x Rainfall increase =
(16000 x (1000)2 x 346 x 20)/( 1000 x 100)
=
110720 x 103 m3
Cost of producing 1 m3 =
(Cost of the experiment ) / (Volume of the water)
1000 liters) of
water produced
by artificial rain)
=
less than 1 paise per 1000 litres of water
Minimum cost of water supplied by =
60 paise per 1000 litres
Municipal /state Government
authorities
Cost benefit ratio of artificial
rain =
1 : 60
Experiments
in Visakhapatnam, 2002 : At
the request of the Municipal Corporation of Visakhapatnam Aerial
Cloud Seeding was undertaken besides two ground based generators located at
Simhachalam hills during 12-14 October 2002. The helicopter used flew for two
hours on each day during 1600 to 1800 hours. The seeding was done by
sprinkling the Sodium Chloride powder of 200 Kg. on each day manually at
heights of about 1 to 1.5 km above the sea level.
The results are reproduced in Fig.
1 to 3 clearly demonstrate the increased rainfall. Assuming the area of the
district where 42 out of 43 reported rainfall during seeding as 10,000 sq.km.
with district average rainfall of 12th as the baseline, the increased water
due to seeded rain is estimated at about 15 TMC. The expenditure involved was
only about Rs.6 lakhs which clearly demonstrate the cheapest and viable
alternative to increase water resources. http://www.geocities.com/jvmnaidu/watershed.html
From the above studies it may be
seen that the cost of cloud seeding varies greatly, depending on a large
number of factors, such as which seeding methods and materials are
appropriate to a specific application, the frequency of seedable conditions,
the size of the intended area of effect and the duration of the project. Most
cloud seeding projects carry favorable benefit/cost ratios, ranging over 20:1
in some cases. http://www.nawcinc.com/wmfaq.html .
https://sites.google.com/site/profshivajirao/cloudseedingelectricity
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