Introduction to Cleantech Stocks
As the energy transition continues to gain urgency, investors should keep an eye on cleantech stocks, including sectors such as low-emission technologies, renewable energy, water and wastewater technologies, and waste and resource efficiency. With the US pulling away from investments in the energy transition made by the previous administration, Australian green companies could pick up momentum. Researchers for Deloitte project that Australia could attract a share of roughly AU$123 billion in clean tech investment, based on an analysis by Net Zero Policy Lab of new supply chain markets.
Top ASX Cleantech Stocks
With the positive outlook for cleantech in mind, here’s a look at 10 ASX cleantech stocks listed in order of largest to smallest by market cap. All figures were current as of May 5, 2025.
1. Rio Tinto
Market cap: AU$159.48 billion
Share price: AU$115.59
Rio Tinto is a major global miner focused on metals vital to the cleantech sector, including copper, lithium, and aluminum. The company has been increasing its focus on supporting clean technologies, exploring carbon-free technology for aluminum smelting through the ELYSIS joint venture. Using the ELYSIS technology, Rio Tinto’s Arvida smelter in Québec, Canada, will produce the world’s first greenhouse gas-free aluminum.
2. Meridian Energy
Market cap: AU$13.93 billion
Share price: AU$5.11
Renewable energy stock Meridian Energy is New Zealand’s largest electricity generator, with five wind farms, seven hydro power stations, and commercial solar arrays. The company’s Harapaki wind farm project reached completion in July 2024 and now stands as the second-largest in New Zealand.
3. Reece
Market cap: AU$10.48 billion
Share price: AU$16.16
Reece is a global leader in wholesale, import, and distribution for plumbing, waterworks, and HVAC-R products in Australia, New Zealand, and the US. Through the Reece Foundation, the company helps connect the trade sector to communities that are in need of clean water and sanitation.
4. Mercury
Market cap: AU$7.65 billion
Share price: AU$5.27
Mercury is a New Zealand-based gas, renewable electricity, and internet provider. The company’s electricity generation comes from a variety of renewable energy sources, including wind, hydro, and geothermal.
5. Contact Energy
Market cap: AU$6.78 billion
Share price: AU$7.89
Contact Energy provides electricity, natural gas, broadband, solar, and renewable energy. It owns and operates 11 power stations and produces 80 to 85 percent of its electricity from its renewable hydro and geothermal stations.
6. Cleanaway Waste Management
Market cap: AU$5.87 billion
Share price: AU$2.64
One of the biggest companies in Australia’s waste sector, Cleanaway Waste is an end-to-end e-waste recycler with 250 branches nationwide.
7. Reliance Worldwide
Market cap: AU$3.2 billion
Share price: AU$4.09
Reliance Worldwide designs, manufactures, and supplies high-efficiency water flow and control products. The company is also a global leader in the manufacturing of push-to-connect behind-the-wall plumbing fittings.
8. Sims
Market cap: AU$2.86 billion
Share price: AU$14.78
Sims Metal, a business division of Sims, has established itself as an integral part of the circular economy through buying and recycling scrap metal, including ferrous and non-ferrous metals.
9. Nanosonics
Market cap: AU$1.48 billion
Share price: AU$4.73
Nanosonics is an infection-prevention company that has commercialized automated disinfection technology. Its Trophon technology, which includes an ultrasound probe high-level disinfection device, is primarily sold to hospitals.
Conclusion
The cleantech sector is rapidly growing, with many Australian companies playing a significant role in the global energy transition. The top ASX cleantech stocks listed above are leaders in their respective fields, from renewable energy to waste management and water technologies. As the world continues to shift towards a more sustainable future, these companies are well-positioned for growth and investment opportunities. With the Australian government’s commitment to reducing carbon emissions and increasing investment in clean tech, the future of cleantech in Australia looks promising.
