Environmentalists used to hear the term ‘treehugger’ a lot, often as an euphemism for someone who would go to any extreme to support an environmental cause. The recent surge in the popularity of solar panels and wind turbines is proof that opinions are changing. People are gradually becoming more aware of their carbon footprints, and even the most conservative thinkers now agree that solar power and wind energy allow financial benefits to the consumer besides saving the planet from pollution and warming.
A major challenge for clean energy is storage. An enormous amount of energy can be generated when the sun is shining, or when the winds are strong. But the excess energy, if not stored, cannot be used after sunset or in less windy conditions or during cloudy weather, when demands often peak. The ‘duck curve’, a solar energy term that originated in California and then spread to other places, has been widely used to describe this phenomenon. With leading economies such as USA, China, India, and Germany investing heavily in solar and wind, finding effective storage solutions appears to be pivotal.
While solar energy can be either electrochemically stored in battery or thermally stored in molten salt, wind energy is battery dependent. Battery technology has been an important area of research over the years, funded by governments as well as private companies across the world. The widely used lithium-ion battery is unfit for large scale storage as it is still expensive and has drawbacks such as overheating and low cycle count. Many are reconsidering molten salt since it can generate electricity for hours after sunset and is easily available.
Solar-wind hybrid systems have so far relied on batteries, and we may still need them, given the stochastic nature of airflow and limited sunlight hours. If an eutectic mixture of salts is able to store thermal energy until sunrise at low costs, then the need for batteries may be eliminated altogether. However, researchers have developed a new battery using a commonly available manganese salt and water. The prototype has a long lifespan and is expected to be a cost-effective solution for grid-level storage if successfully scaled up. Whether molten or dissolved, salts are changing the way we think about energy and thanks to these naturally abundant minerals, electricity may become an inexpensive commodity in the near future.