Supercapacitors Rapidly Replace Batteries for Energy Storage
Along with automotive and IT applications, grid storage looks most promising as renewable energy sources soar higher — literally, in some cases. Those sources include airborne wind energy (AWE) generators tethered to drones or even kites, reaching stronger and more consistent winds aloft than conventional wind turbines.
The Italian company KiteNRG is developing an AWE system with up to 500 kW of capacity. “The high-altitude winds in the troposphere represent an untapped energy source that is larger than the world’s current energy needs,” the company asserts.
According to market analyst IDTechEx, the Italian energy harvesting design requires supercapacitors in an “island configuration” to handle anticipated power surges. Another reason for that off-the-grid mode is that energy harvesting technologies such as ocean wave and tidal stream schemes must operate continuously and reliably in remote locations.
Along with capturing more energy surges than conventional batteries, supercapacitors also waste less electricity. IDTechEx estimates supercapacitors used for energy harvesting deliver roughly100 times the endurance along with “deep discharge” when compared to batteries, “whereas only 15 percent of the battery [capacity] can be sipped.”
In energy cycling applications, supercapacitors also outperform battery storage in terms of kilowatts-per-hour needed to replace a battery. That metric offsets at least some the cost of supercapacitors, a trait the market analyst noted has been demonstrated in hybrid cars.
Still, load-bearing supercapacitors continue to lag behind battery technology when it comes to energy density, a key consideration for improving the range of electric vehicles. The latest lithium-ion batteries still yield energy densities on a par with fuel cells, but supercapacitors’ relatively high power density (as measured by the amount of power in a given mass) means they outperform batteries based on the amount of storage space available.
IDTechEx notes that battery-supercapacitors hybrids are emerging that seek to leverage the advantages of both energy storage technologies. That may help reduce supercapacitor sticker shock: large versions still cost thousands of dollars. One potential return on that investment is potentially millions in savings by preventing damaged wind turbine blades in heavy storms.
The market tracker concludes with another full-throated endorsement of supercapacitor technology: “Compared to batteries, supercapacitors are safer, tolerate overcharge [and] avoid complex battery management systems.” The technology is increasingly non-flammable, non-toxic and, unlike batteries, requires no expensive controlled disposal.
And for emerging deployments like airborne wind generators, IDTechEx estimates supercapacitors waste 14 percent less electricity and capture up to twice the regenerative energy from airborne wind energy platforms.
Energy storage has long been the weak link in the push for renewables. As technology startups and a growing list of supercapacitor suppliers (see chart) tap into more sources of potential energy, the retrieval, stowing and management of renewable power sources looks more promising.