Over the past century, human activities have released large amounts of carbon dioxide (CO2) and other greenhouse gases (GHG) into the atmosphere resulting in temperature rise by 1.5°F. Majority of GHG come from burning fossil fuels to produce energy, although deforestation, industrial processes, and some agricultural practices also emit gases into the atmosphere.
The six critical greenhouse gases that impact climate change is:
- Carbon dioxide
- Nitrous oxide
- Sulphur hexafluoride
Amongst these carbon-dioxide has the maximum impact on climate change.
GHG act like a blanket around Earth, trapping energy in the atmosphere and causing it to warm. This phenomenon is called the greenhouse effect. Build-up of GHG can change earth’s climate and result in dangerous effects to human health and welfare and to ecosystems.
Recycling of solar panels – further aiding fight climate change
Further contribution of temperature on the planet can translate to large and potentially dangerous shifts in climate and weather. Hence the need of the hour is to reduce the greenhouse gases to the year 1990 levels (identified as base year) by reducing fossil fuel and exploring renewable energy sources like solar and wind as one of the answers. Limiting global warming to 1.5°C is not impossible – but it would require unprecedented transitions in all aspects of society.
Renewable energy sources like solar and wind are rapidly advancing to fulfil the energy demand and are likely to act as substitutes to fossil fuel-based energy in future. Energy from solar photovoltaic (PV) cells is eco-friendly but producing them has a carbon footprint. The energy required to make a solar panel from mining basic raw materials in the ground to finished panel is called the ‘embedded energy’ or ‘lifecycle energy’ cost. The solar panel only takes around two years of the panels working life to recover this embedded energy and perhaps still lesser if high efficiency panels are used.
Figure 1: Solar Modules all set for disposal
The second issue is how much GHG is avoided from solar power, with the typical focus on CO2, the most significant greenhouse gas from fossil fuel electricity generation. Each Megawatt-hour (MWh) of electricity generated from conventional sources creates approximately 90 kilograms of CO2. Every 1 MW solar system in India will yield average 1,600 MWh annually which will save around 150 tonnes of CO2 emissions annually. Taking into account the two years to pay off the embedded energy in the panel, after 25 years a 1 MW system will have a net saving of around 3,000 tonnes of CO2. Thus, any solar system assists in addressing climate change issues by lowering CO2 emissions.
A crystalline solar cell is made from silicon feedstock, which is further processed into wafer and cell. The complete solar energy system comprises of glass, aluminium frame, laminate, mounting and cabling, inverter, takeback for recycling. These entire materials have carbon footprints ranging from 21 to 29 kilograms of carbon-di-oxide per megawatt hour (MWh), Nearly 50% of the carbon footprint goes into converting raw material to finished goods like cell, inverter, frame, cables, laminate, etc. Against this coal-based power has carbon footprint between 500 -600 kilograms of MWh.
Nett abatement of carbon-dioxide
The break-up of the materials that can be recovered by recycling per 1,000 kg of waste solar PV panel is as shown in Table 1. The recovery rate is between 70 % to 100%, except for the polymer sheets.
|Material||Percentage by net weight||Rate recovered %||Recovered material|
|Glass, containing antimony (0.01-1 %/kg of glass)||70%||80%||Primary white glass|
|Aluminum frame||18%||100%||Primary aluminum|
|Copper connector||1%||90%||Primary copper|
|Polymer-based adhesive (EVA) encapsulation layer||5.1%||0%||Diesel fuel (pyrolysis)|
|Back-sheet layer (based on polyvinyl fluoride)||1.5%||0%||Diesel fuel (pyrolysis)|
|Silicon metal solar cell||3.56%||70%||Metal grade silicon|
|Aluminum, internal conductor||0.53%||100%||Primary aluminum|
|Copper, internal conductor||1.14%||95%||Primary copper|
|Various metal (tin, lead)||0.053%||80%||Primary metal|
Table 1: Break-up of materials that can be recovered from a 1,000 kg waste solar PV panel (source: Joint Research Commission, EU 2016 report)
Government of India has set a target of 450,000 MW of renewable energy by the year 2030 and solar energy is likely to contribute about 70% or say 300,000 MW.
Every MW of solar panel weighs approximate 50 tons. If all the panels are left un-treated at the end of their life then by the year 2050 there will be 15 million tons of waste lying. If they are stuffed in a standard 40 feet container they will virtually occupy 6,000 kms of length, which is almost the distance Delhi-Ahmedabad-Mumbai-Bengaluru-Chennai-Kolkata-Delhi.
Figure 2: Projected solar photovoltaic waste in India until 2050
If these panels are recycled, then almost 80% of raw material is recovered back for use into making of new panels. Thus 240,000 MW of new panels can be re-produced without extracting new materials. 50% of the 3,000 tons CO2 per MW will be abated by avoiding extracting of raw materials. This will result in overall CO2 abatement of 360 billion tons (240,000 MW x 1,500 CO2) in their lifetime.
The new 3R’s of solar panel recycling will thus be Recycle, Reduce and ReGenerate/Reject.
Jaideep N. Malaviya, Solar energy Expert