Last weekend, U.N. Secretary General Ban Ki-moon inaugurated a new
"canal-top" solar energy plant in Vadodara district in India's
western state of Gujarat.
"I saw more than glittering panels – I saw the future of India and
the future of our world," said Ban. "I saw India's bright
creativity, ingenuity and cutting-edge technology."
Experts identify two major advantages in building solar plants atop
canals: efficient and cheap land use, and reduced water evaporation
from the channels underneath.
Earlier this month, India showed it is serious about expanding
energy production from renewable sources. Prime Minister Narendra
Modi upped the country's investment target for solar alone to $100
billion, saying India would scale up solar power to over 10 percent
of its total energy mix by 2022.
As part of that effort, the Ministry of New and Renewable Energy
plans to create 100 megawatts (MW) of capacity from grid-connected
solar photovoltaic (PV) power plants built on top of canals and on
their banks by the end of the government's latest Five Year Plan in
2017.
The ministry will subsidize 30 percent of estimated expenditure of
$154 million to construct facilities to meet the canal-top goal.
The 10 MW plant on the outskirts of Vadodara city, which began
generating power in November, is built across 3.6 km of irrigation
canal, and has 33,800 solar panels mounted on steel scaffolding.
Connected to the state grid, its output is intended mainly to meet
demand from irrigation pumping stations. On a sunny day, the plant
generates 50,000 units of electricity (1 unit equals 1 hour of
1,000-watt usage), and is scheduled to produce 16.2 million units in
its first year, declining 1 percent annually as the panels degrade.
A quarter of the PV panels for the plant were procured from India,
with the rest imported from China.
Completed in under six months, the plant's $18.3 million cost -
including 25 years of operation and maintenance - is recoverable in
13 years, according to Umesh Chandra Jain, chief engineer with
Sardar Sarovar Narmada Nigam Ltd (SSNNL), the Gujarat government
agency that administers this facility and another smaller one.
CHEAPER POWER
The cost of producing 1 unit of electricity at the plant is 6.5
rupees ($0.105). SSNNL is entitled to use the same amount of power
it feeds into the grid without paying the standard price of Rs7.5 to
Rs8 per unit, Jain said.
Engineer Navin Reddy with Hyderabad-based Megha Engineering &
Infrastructures Limited (MEIL), which constructed the plant, said
canal-top plants are more expensive to maintain.
But the company incorporated side bars on the scaffolding and
walkways between the panels so they can be reached easily for
cleaning.
The 10 MW plant follows another smaller plant in Gujarat,
commissioned in April 2012, 45 km from the state capital Ahmedabad.
Set up along a 750-metre stretch of canal, the 1 MW plant has so far
generated 4.35 million units of electricity.
The plants are part of the Sardar Sarovar project, a hydropower and
irrigation scheme that aims to water 1.8 million hectares (4.45
million acres) of land in Gujarat and Rajasthan through 75,000 km of
canal yet to be completed.
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Both the solar power plants are built on branches of the main canal,
though which irrigation water runs from a dam on the Narmada River.
According to SSNNL, the 10 MW plant has saved on 16 hectares of
land, and will potentially prevent 90 million liters of water from
evaporating each year.
In general, Jain noted that lower temperatures due to the water body
below the canal-top plants boost panel efficiency by around 7
percent.
ENVIRONMENTAL IMPACTS?
But the higher construction cost of these plants – because of the
use of more structural steel – is a disadvantage, said Anand
Upadhyay, associate fellow with The Energy and Resources Institute
(TERI) in Delhi.
The 1 MW canal-top plant cost $2.8 million, according to SSNNL,
whereas a 1 MW land-based solar plant costs $2.3 million.
Another problem is that PV panels are usually mounted facing
southwards for optimal performance, but a canal might curve and
change direction. Using only north-south stretches of water could
limit the scale of canal-top plants, Upadhyay said.
Long-term exposure to environmental stresses and ingress of water
into the panels could reduce their performance, he added.
Further concerns center on the potential environmental impacts of
canal-top plants on their surroundings, as the risks remain unclear.
For example, Upadhyay said canal water could be contaminated by
chemicals used on the plant’s scaffolding for maintenance. But SSNNL
engineer Tejas Kedariawho said such fears may be unfounded because
the canal water is flowing, not stagnant.
Others have raised questions about keeping long stretches of PV
panels secure. MEIL's Reddy said 18 CCTV cameras fixed along the
length of the Vadodara plant are monitored 24 hours in control
rooms, while patrol vehicles are also in operation.
Solar power is mooted to be on the agenda when U.S. President Barack
Obama visits India in the last week of January. India's prime
minister is expected to make a strong pitch for U.S. investment in
climate-smart technologies in India, particularly in the solar
sector.
(Reporting by Manipadma Jena; editing by Megan Rowling)
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