Italian company stores renewable energy using giant balloons

Energy Dome is using carbon dioxide balloons to store energy from wind and sunlight, thereby ensuring electricity supply.

Energy Dome's balloon energy storage prototype in Ottana. Photo: DNYUZ

In Ottana, Sardinia, on the abandoned site of a former petrochemical plant, a new technology is taking shape that could help slow the pace of climate change. The main ingredient of this technology is carbon dioxide, the main cause of global warming. Energy Dome, a Milan-based startup, operates an experimental energy storage plant that promises to address disparities in the local electricity market. "In Sardiania during the day, people go to the beach. They don't use a lot of electricity, but the supply is a lot," said Claudio Spadacini, Energy Dome's chief executive, referring to the abundant sunlight on the Italian island .

Energy Dome uses carbon dioxide contained in a giant balloon that the company calls a "dome" as a battery. During the day, electricity from the local grid, including electricity produced in nearby solar cell fields, is used to compress carbon dioxide into a liquid. At night, liquid carbon dioxide changes back into gas, turning turbines and producing electricity to send back to the grid.

Wind power and solar power are the fastest growing renewable energy sources, but depend on nature to produce electricity so are susceptible to interruptions. Many researchers say storing renewable electricity for hours or days until needed is key to moving the economy away from fossil fuels.

For decades, many power plants have handled fluctuating demand with pumped storage, generating electricity when demand surges, then pumping water from a lower reservoir to a higher reservoir to store the energy. when there is excess supply. Some facilities install pumped storage hydropower to balance wind and solar power generation. Other facilities install lithium-ion battery packs to store excess energy generated by renewable sources. But these storage methods have many limitations. Pumped storage hydropower requires transformation of mountainous landscapes and is costly to build. Lithium is a limited resource and becomes prohibitively expensive when designed to store energy longer than 4 hours.