Water use - indiaenvironmentportal · to thermal power. While specific water consumption is lower,...

Water usein solar power sectorSeptember 2018

2© BRIDGE TO INDIA, 2018

© 2018 BRIDGE TO INDIA Energy Private Limited

AuthorsDeepak Singhal, BRIDGE TO INDIASangeetha Suresh, BRIDGE TO INDIAShipra Arora, BRIDGE TO INDIASurbhi Singhvi, BRIDGE TO INDIAVinay Rustagi, BRIDGE TO INDIA

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1. IntroductionIndia’s solar sector is growing rapidly – total installed capacity has risen from just 1 GW in 2012 to over 25 GW at present and is expected to go up by over 50 GW in the next five years.

Optimal operation and utilisation of solar plants is dependent, amongst other factors, on regular cleaning requiring extensive use of water. Soiling of solar panels drastically reduces power generation and negatively impacts project economics. Water consumption is much lower in comparison to thermal power plants – an average 0.1 m3/ MWh as against 2.2 m3/ MWh for thermal plants1. But procurement is nonetheless a considerable operational burden as solar plants are usually located in remote, arid regions with acute water shortage. Making matters worse, location of solar plants is highly concentrated – top 5 states account for 70% of total installed capacity and average solar project size continues is increasing every year.

Rapid growth and concentration in water-stressed areas exposes solar projects to a growing water risk – scarcity, rising cost, conflict with other social and economic uses and environmental degradation.

Figure 1.1: Distribution of solar power in top ten states

Madhya Pradesh 7%

Uttar Pradesh 4%

Rajasthan 12%

Gujarat 6%

Maharashtra 6%

Karnataka 23%

Telangana 14%

Andhra Pradesh 12%

Tamil Nadu 8%

Punjab 3%

Source: BRIDGE TO INDIA research

1Parched Power: Water demands, risks and opportunities for Indian power sector, WRI, 2018, BRIDGE TO INDIA research

Water procurement is a considerable operational

burden as solar plants are usually located in arid regions

with acute water shortage


2. Water requirement in the solar sectorRegular cleaning of solar panels is necessary as soiling due to accumulation of dust, dirt, pollution, bird-droppings etc. can cause generation losses of 3-6%. To produce power at a competitive price, these ‘soiling losses’ need to be reduced to about 1% - typical operating assumption in most cases – requiring an average of two cleaning cycles per month. Even short duration of water unavailability can materially affect project returns.

Interviews with developers and O&M players across the country show high level of variation in water usage. Wasteful use is particularly common in southern regions where water availability is relatively better.

Figure 2.1: Variations in water use, litres/ module/ cycle

0

1

2

4

5

3

1 2 3 4 5 6

Minimum Maximum

Average consumption

Developer responses

Source: Industry interviews

We have estimated water consumption in each state based on installed capacity and average water consumption. We have then mapped water usage to water availability to assess water risk for the solar sector.

To produce power at a competitive price, ‘soiling

losses’ need to be reduced to about 1% - typical operating assumption in most cases – requiring an average of two

cleaning cycles per month


Figure 2.2: Estimated water consumption in the solar sector by state

Almost 94% of solar capacity in India is exposed to medium-high level of water risk. It is imperative that water usage and adoption of suitable mitigation technologies receive more attention from both policy makers and project developers/ contractors.

At least 18% of the country’s installed capacity that is located in arid zones western India are exposed to extremely high levels of water risks. 38%, located in high water-stress parts of central and southern India, fall under high risk zones. Yet another 38% fall under medium to high risk category.

Source: BRIDGE TO INDIA research; India Water Tool, World Resources Institute Note: Water consumption has been estimated based on installed capacity as on June 30, 2018.

Gujarat

Telangana

Tamil Nadu

0

200

400

800

1,000

1,200

Wat

er c

onsu

mpt

ion

(’000

m3 /

year

)

Water stress level

600

Low Medium High Very High

Karnataka

Maharashtra

AndhraPradesh

Rajasthan

Punjab

Haryana

MadhyaPradesh

Uttar Pradesh

KeralaWest Bengal

Bihar

Chattisgarh

Uttarakhand

Odisha


Source: BRIDGE TO INDIA research; India Water Tool, World Resources Institute Note: Water consumption has been estimated based on installed capacity as on June 30, 2018.

Figure 2.3: Water-risk exposure for solar power plants in India

Madhya Pradesh

Uttar Pradesh

Haryana

Rajasthan

Gujarat

Maharashtra

Karnataka

Telangana

AndhraPradesh

Tamil Nadu

Punjab

Very high

High

Medium to high

Medium

Low


3. Water availability, sources and costBulk of the water (60%) used for cleaning in solar sector is sourced from ground through borewells while the remaining (40%) comes from surface water sources such as rivers, canals and lakes. Ground water is preferred by most developers and O&M contractors as it is almost free and is operationally expedient. But it requires specific regulatory permissions although there are various reports of illegal extraction.

Figure 3.1: Sources of water for solar power

Source: BRIDGE TO INDIA research

We have interviewed several industry players to get estimates of cleaning costs. Using ground water, cost of module cleaning primarily depends on labor cost and ranges from INR 42,000-66,000/ MW per year. There may be an additional cost for water treatment if water quality is unsuitable for direct use (total dissolved solids > 500 ppm).

If surface water is used, procurement responsibility is almost always outsourced to a vendor, who supplies water through tankers. In this case, the cost of cleaning rises to between INR 79,000-105,00/ MW per year depending upon location, source and quality of water. The higher costs are in observed the dry states of Rajasthan and parts of Gujarat. In parts of Rajasthan, water cost has almost doubled in the last 3-4 years due to sharp increase in demand. Sudden increase in water costs also pose a risk. For example, Karnataka hiked tariff for water meant for industrial use by 100 times in 2018 . Such drastic, unforeseen increase can substantially affect project economics since cleaning accounts for a significant 26-35% of total O&M cost if surface water is used and 14-22% if ground water is used. Conflicts over water use between industry and other users are also becoming more common.

Figure 3.2: Cost of module cleaning as a percentage of total O&M costs

Surface water

Ground water

Cost of module cleaning Other O&M costs

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Source: Industry interviews, BRIDGE TO INDIA research

In parts of Rajasthan, water cost has almost doubled in the

last 3-4 years due to sharp increase in demand

Surface water, 40% Ground water, 60%


Wate r u se for so lar Cost o f water

Water consumed by solar power, m³/ MW/ year

Current installed capacity of solar power, GW

New annual capacity addition over the next few years, GW

174

25

10

Solar capacity, GW

Wat

er c

onsu

med

, 000

m3 /

year

0

2,0 0 0

4 ,0 0 0

6 ,0 0 0

8 ,0 0 0

10,0 0 0

12,0 0 0

25 35 45 6555INR 54,075/ MW/ yearINR 91,875/ MW/ year

Surface water Ground water


Water use fo r so lar Co st o f water

Water consumed by solar power, m³/ MW/ year

Current installed capacity of solar power, GW

New annual capacity addition over the next few years, GW

174

25

10

Solar capacity, GW

Wat

er c

onsu

med

, 000

m3 /

year

0

2,000

4 ,000

6 ,000

8 ,000

10,000

12,000

25 35 45 6555INR 54,075/ MW/ yearINR 91,875/ MW/ year

Surface water Ground water


4. Technologies for mitigating water useIn view of the increasing challenges in procuring water and rising costs, the larger developers have begun to actively manage their water consumption. They are trying to reduce consumption by using new technologies, improve procurement options and manage community impact through local engagement initiatives. One of the developers we interviewed is exploring rainwater harvesting to reduce conflicts with the local population over water usage.

There are two specific technologies being explored by developers and O&M contractors to mitigate water risk in the sector.

Robotic cleaning

There are many different types of robotic cleaning – with and without water. Robotic cleaning can reduce water consumption by 50-100% and has been commercially proven. It started gaining acceptance in India about two years ago and has gained significant traction in the past year. Around 3 GW of power plants are currently considering various types of robotic solutions.

Upfront capital cost of a robotic cleaning solution is about USD 1.6¢/Wp, an increase of around 3% to the total capital cost. Because of regular and more uniform/ methodical cleaning, robotic cleaning usually leads to generation gains of 1-2% per annum. Payback period is believed to be about 2-3 years in most cases.

Anti-soiling coating

Anti-soiling coatings for modules have been around for many years but have improved significantly in recent years. The ‘after- market’ solutions, where coating was applied after installing modules, were not popular as developers were apprehensive about their longevity and adverse impact on module performance/ warranties. But many module manufacturers are now offering integrated anti-soiling coating as a special add-on feature with complete lifetime warranties. Capital cost of such modules is usually higher by about USD 0.50 ¢/Wp. Water consumption is reduced by up to 35-50%, plus there is an added benefit of 1-2% incremental power output depending on project location and type of soiling.

Robotic cleaning and anti-soiling coating are not necessarily alternative solutions. They can be used together or in isolation. There are other new technologies such as hydrophobic, nanotechnology-based self-cleaning modules, which are currently in test phase.

Developers are trying to reduce consumption by using

new technologies, improve procurement options and

manage community impact through local engagement

initiatives

Module manufacturers are now offering integrated anti-

soiling coating as a special add-on feature with complete

lifetime warranties


5. ConclusionSolar power has been acknowledged as a water-efficient alternative compared to thermal power. While specific water consumption is lower, water associated risks are higher as solar plants are typically located in dry regions and there is little headroom in cash flows to deal with rising cost and/or operational underperformance.

Water use can be optimized by benchmarking consumption levels and following industry best practices. Ideally, mapping and assessment of water availability at proposed plant locations should be completed prior to tender issuance. Policy makers should also consider specifications for maximum permissible water use and introduce norms for ensuring transparency in water procurement.

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