Tashkent, Uzbekistan, 100084
Disposal of elements of RES systems
Investment in renewable energy sources (RES) has gained momentum in recent years, outpacing growth in other forms of energy production, and this trend is likely to continue in the near term. According to The International Renewable Energy Agency (IRENA), global renewable generation capacity will total 3,372 GW at the end of 2022. Renewable hydropower accounted for the largest share of total global capacity at 1,256 GW (~36%), with solar and wind taking up most of the remaining capacity at 1,053 GW (~31%) and 899 GW (~27%), respectively. Other renewable energy sources include 149 GW of bioenergy and 15 GW of geothermal, as well as 524 MW of marine energy.
Figure 1: Global renewable energy capacity growth at the end of 2022
It is well known that any such development must carry risks or costs, and such in the renewable energy sector are the wastes associated with photovoltaic panels, wind turbines and battery storage systems, which are becoming a necessity to ensure the stability of the electricity system, the flow of electricity and the removal of surplus electricity production during peak periods. The international community faces an important question - What will happen to the millions of solar panels, battery storage cells and wind turbines when they reach the end of their useful life? Despite the fact that solar panels and wind turbines have lifespans of 20-30 and 15-25 years respectively, there will somehow come a point when thousands of spent cells and industrial waste will require special infrastructure for their disposal.
Photovoltaic (PV) panels
Solar power is one of the fastest growing renewable energy sectors. According to IRENA, at the end of 2022, installed solar power capacity reached 1,053 gigawatts and is expected to grow further to 8,519 gigawatts by 2050, 18 times more than today! That can be achieved if the rate of solar capacity construction increases to 270 GW per year by 2030 and to 372 GW by 2050 [3]. These are very impressive figures if we account that the "boom" in solar energy has started relatively recently.
Figure 2: Forecast of solar power capacity increase by 2050
IRENA estimates that the annual volume of solar panels and battery cells waste worldwide will be around 5.5-6 million tons by 2050, which is more than 10% of all e-waste[1] that is generated a year on Earth today. Therefore, the issue of solar panel recycling requires a comprehensive approach, taking into account the need to develop and test recycling technologies that ensure the economic feasibility of implementing such technologies, if possible.
At the same time, almost 95% of the materials used in solar modules can be recycled, allowing valuable resources to be put back into circulation, which can be beneficial from an economic point of view. The remaining 5% is mainly dust caught in the filters after crushing, which can be used, for example, as a substitute for sand in construction.
[1] Electronic waste (abr. WEEE, e-waste) is a type of waste containing discarded electronic and other electrical devices and their parts. Electronic waste can have high hazard classes due to the substances it contains, such as lead, mercury, polychlorinated biphenyls, polyvinyl chloride (due to the appearance of dioxins during combustion).
Figure 3: Waste solar panels
Solar modules are composed of glass, aluminum, copper, and semiconductor materials that can be recovered and reused. Conventional crystalline silicon panels consist (by weight) of 76% glass, 10% polymeric materials, 8% aluminum, 5% silicon semiconductors, 1% copper, less than 0.1% silver and other metals including tin and lead. In thin-film modules, the share of glass is much higher - 89% (CIGS) and 97% (CdTe).
To date, there are 2 ways to recycle PV panels:
- “Thin”: involves the removal of almost all the components of the PV cells and their further processing. First, the frame and junction box are removed, then the laminating film is removed, glass, metals, silicon elements, plastic are extracted
- “Rough”: involves the extraction of only basic materials - glass, aluminum. This is the preferred method of recycling today, but it does not allow for proper treatment of valuable and hazardous solar waste.
Today, up to 65-70% (by weight) of the materials that make up solar modules are recovered for recycling in Europe, which is in line with the EU WEEE Directive. The European Committee for Electrotechnical Standardization (CENELEC) has developed an additional standard for panel collection and recycling (EN50625-2-4 and TS50625-3-5).
Stages of solar panel recycling:
- Disassembly of the PV cells to separate glass and aluminum parts, where up to 95% of the glass can be reused. The metal parts can be used to re-create the frames;
- Heat treatment of the remaining cells at 500°C to separate the silicon from the plastic;
- Additional cell cleaning;
- Melting of wafers for reuse in the production of new PV cells;
- Disposal of photovoltaic panels.
In addition, it is already possible today to produce a solar panel consisting of 100% recycled materials. Its efficiency will be slightly lower than that of modern premium analogs, but higher than that of the vast majority of old modules.
In some countries, PV panel and battery manufacturers are required by law to comply with recycling standards. Below is a table with the regulatory framework for solar waste disposal in a number of countries around the world.
[2] Directive 2012/19/EU of the European Parliament and of the Council of 4 July 2012 on waste electrical and electronic equipment (WEEE) – https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A32012L0019
[3] Resource Conservation and Recovery Act (RCRA) – https://www.epa.gov/rcra
[4] The solid waste management rules, 2016 – https://hspcb.gov.in/content/laws/msw/MSW_Rules.pdf
[5] Waste Management and Public Cleansing Law – https://www.env.go.jp/en/recycle/basel_conv/files/Waste_Management_and_Public_Cleansing.pdf
Batteries
Solar energy storage is the process of collecting and storing the energy that comes from the sun's rays. This energy can be used for various purposes such as providing electricity to homes, heating water or even powering cars.
Solar energy storage plays an important role in providing a sustainable source of energy. But in order to utilize solar energy efficiently, it is necessary to choose a suitable storage technology. Currently, two main technologies are the most common: chemical energy storage and thermal energy storage.
Chemical energy storage is accomplished through solar energy storage batteries. These are devices that help convert solar panel energy into electricity for indoor use. Batteries can be of different types including lead-acid, lithium-ion and nickel-cadmium. Each type of battery has its own advantages and disadvantages, and the choice depends on the specific needs and constraints.
Thermal energy storage involves using the heat from solar collectors to heat a heat transfer medium. The heat transfer medium can be water, salt or other heat storage materials. The heat transfer medium is heated in the thermal storage and can then be used for space heating or hot water even after sundown. This technology is particularly useful for heating buildings during cold seasons.
Two types of batteries used nowadays - alkaline and acid batteries, which are made of poisonous components, as well as various heavy metals. Lead, nickel, lithium and other dangerous compounds are not only dangerous in themselves, but also because they can react with each other over time.
The composition of any battery contains:
· Alkalis;
· Acids;
· Heavy metals.
Over time, harmful substances get into the soil, water bodies, which can cause significant damage to the environment on a large scale, if the unit is not properly utilized, but simply disposed of in a landfill. That is why the legislative norms dictate the mandatory process of collection and processing of this type of household waste and regulate this process. Following them allows to reduce the share of toxic emissions that harm the nature, reducing the risk of deterioration of the environmental situation as a whole.
Technology of recycling of batteries:
- Electrolyte removal on a special technological line. Automation of the process allows to avoid human exposure to harmful vapors.
- Crushing of feedstock in a crusher with simultaneous treatment with soda solution neutralizing electrolyte residues.
- Separation of the metal-containing fraction in an electromagnetic separator.
- Sorting of large elements on a vibrating device for their re-sending for grinding.
- After decontamination and separation, two fractions are obtained - lead and polymer component.
The manual method of battery recycling is still relevant, but more dangerous. This is dictated by the expensive cost of the equipment needed to organize the process on an industrial scale. Only highly qualified masters can engage in this type of activity, because ignorance of the basics of the correct approach can cause serious harm to health. Although this method allows to obtain raw materials of higher quality, it is increasingly preferred to abandon it.
Wind turbine blades
Today, the standard service life of an onshore wind farm is about 15-25 years. Disposal of wind turbine spare parts is a vulnerable part of the wind power industry, although up to 85-90% of wind turbine components and spare parts can be recycled. For example, the mast and other parts of a wind turbine installation are recycled as an ordinary scrap metal.
Another thing is wind turbine blades, which are made of composite materials (usually a combination of reinforced fibers and polymer matrix is used), which makes the recycling process more labor-intensive and unprofitable. But, thanks to these composites, the performance of wind turbines is increased, as they allow the use of lighter and longer blades with optimal aerodynamics.
Figure 4: Waste wind turbine blades
The recycling of composite materials is a current challenge not only for the renewable energy sector, but also for other industries, such as the automotive or urban development sectors, where the consumption of these materials takes place in much larger volumes. Active involvement of all composite stakeholders is required to develop cost-effective solutions and strong value chains.
To date, there are technologies available for processing composite materials, but these solutions are not mature enough, often not available on an industrial scale and are not cost competitive. Making these technologies commercially viable will require support from policy makers, other users of composite materials and recyclers.
Figure 5: Life cecle of wind turbines
In Europe's most mature wind energy markets, 1st generation turbines are nearing the end of their service life. According to WindEurope’s [6] forecasts, about 25,000 tons of blades will reach the end of their life each year by 2025. Germany and Spain will have the largest number of decommissioned blades, followed by Denmark. By the end of the decade, Italy, France and Portugal will also begin to decommission blades, and annual decommissioning could double to 52,000 tons by 2030.
The main current technology for utilization of composite waste is its use in cement production (as an energy raw material and additive) through blade grinding. This helps to reduce CO₂ emissions and water consumption compared to the traditional cement production process.
The Danish company Vestas offered an innovative solution to this issue by developing a new technology that provides recycling and reuse of thermoset composites. The new technology provides a recycling process consisting of two stages. First, thermoset composites are disassembled into fiber and epoxy resin. Second, through a new chemical process, the epoxy resin is further separated into basic components similar to the original materials. These materials can then be reused in the production of new wind turbine blades.
In addition, leading wind turbine manufacturers Vestas and Siemens Gamesa have committed to zero waste for their wind turbines by 2040.
[6] WindEurope is the association promoting wind energy in Europe. Based in Brussels, it has over 600 members operating in more than 50 countries, including manufacturers with a leading share of the global wind energy market, component suppliers, research institutes, national wind and renewable energy associations, developers, contractors, power suppliers, finance companies, insurance companies and consultants.
Conclusion
It is worth noting that recycling is a natural life cycle of any production. Photovoltaic panels, wind turbines and batteries are no exception. To date, waste from solar and wind power plants is not a significant global problem, as their volumes are small in the total share of electronic waste (e-waste) generated annually on our planet.
It should be noted that solar panels are already utilized on an industrial scale in a number of countries, using currently available technologies, which are still quite labor-intensive and expensive, which makes the recycling cycle generally unprofitable. The issue of utilization of wind turbine elements is also relevant, although there are some developments in this area, which are still applied on a small scale, but the main problem is the utilization of wind turbine blades made of composite materials, which are difficult to recycle and, in some countries, they are simply buried in the ground to a depth of up to 10 meters.
When it comes to Uzbekistan's RES sector, it is a relatively new energy sector. Hydropower, which is also considered to be a renewable energy sector, is quite developed in the country. Steps are being taken to build capacity in small hydropower.
Of particular note is the planned growth in solar and wind power. In the coming years, new solar and wind power plants with nominal capacities of 5 GW (excluding the capacity of individual households) and 3 GW, respectively [7], are planned to be built and commissioned.
Today, Uzbekistan is developing and supplementing the regulatory and legal framework in the field of renewable energy aimed at stimulating the development of this sector. The issue of RES waste utilization is not yet on the agenda for Uzbekistan, as the planned and commissioned capacities are not that large.
We believe that in order to achieve the main objectives of the RES development, namely reducing the carbon footprint in nature and ensuring "greenness" of the energy sector along the entire chain of power generation and distribution, the issues of utilization of renewable energy materials should be considered at this stage of the country's transition to "green energy", through the development and implementation of a regulatory framework that ensures and obliges renewable energy producers to address the issues of safe waste disposal responsibly.
List of sources used:
2. https://reenergo.ru/blog/kak-proishodit-utilizatsiya-solnechnyh-batarey/
3. https://getmarket.com.ua/ru/news/novyj-doklad-o-budushem-solnechnoj-energetiki-ot-irena
4. https://sacred-sun.com/stati/utilizatsiya-akkumulyatorov
https://obzorposudy.ru/polezno/akkumulyaciya-solnecnoi-energii-principy-i-preimushhestva
[7] Decree of the President of the Republic of Uzbekistan "On measures to radically improve the management system of the fuel and energy industry of the Republic of Uzbekistan - https://lex.uz/ru/docs/4188806
