Providing reliable electricity is a complicated and expensive process. Any imbalance between supply and demand will damage a power system’s stability. For utilities to handle extra loads or deal with outages, they build more facilities, but that increases their costs and raises rates for customers.
Using energy storage systems could solve the problem, leading to better operational efficiency and improved quality of power through frequency regulation. Power companies could produce electricity when it’s cheapest and most efficient while providing an uninterruptible source of electricity for mission-critical infrastructure and services.
There are currently a few types of storage systems such as mechanical storage systems, electrochemical, and thermal energy. Most of them are not that efficient, however, and it costs a lot to build them. Simply put, they don't fulfill the requirements of today’s sophisticated power systems. The electricity grid—with its increasing demand and widespread adoption of renewable energy sources such as wind and solar—needs new types of electrical energy storage that can help create a continuous, reliable stream of power and reduce generation costs. That could be achieved through long-term systems such as large-scale utility-size battery storage technologies.
Batteries store electrical energy in the form of chemical energy, which is then converted back into electricity when needed. Generally, battery-related energy storage projects are based on lead-acid, lithium-ion, nickel-based, sodium-based, or flow batteries. A report from Morgan Stanley released in August 2017 predicted the demand for energy storage would increase from less than US $300 million last year to $4 billion in the next two to three years.
The race is on to find better battery reserve systems that can be integrated across the grid to increase renewables’ integration; enhance grid operations; reduce energy costs; and enable more distributed, local generation. Several new technologies are being tested, and older ones are being improved.
Utilities in Arizona, California, and New York have proposed electrical energy storage modernization plans. Arizona in January unveiled plans that call for an 80 percent clean energy target by 2050, coupled with a 3,000-megawatt energy storage target for 2030. California and New York each have 50 percent renewable energy targets for 2030, and storage targets of 1,300 megawatts and 1,500 megawatts, respectively, according to a Greentech Media article.
GE Power recently unveiled Reservoir, a flexible, compact energy storage system for AC or DC coupled systems. According to GE, the Reservoir condenses 4 megawatt hours and 10 years of energy storage experience into a 6-meter box, delivering an estimated 15 percent improved life cycle on the batteries and 5 percent higher efficiency.
After a series of blackouts last year in Australia and Puerto Rico, Tesla CEO Elon Musk promised to complete and deliver the world’s largest grid-scale, power reserve battery. The giant batteries reached 31 MW in two minutes. The 100-MW battery is enough to keep almost 30,000 houses powered for an hour until traditional backup generation sources come online. The huge battery can helped stabilize the grid in the area, which gets more than 40 percent of its electricity from wind energy and needs help when the wind dies down.
The Tesla battery delivered 100 MW into the national electricity grid in 0.14 seconds. The company also completed a 20-MW battery in South Australia, and planned to build a third one larger than the first two projects.
Several large companies have launched energy storage projects. The Korean car company Hyundai is developing a 1-megawatt-hour energy storage system made of used battery packs from its electric vehicles. The system will be deployed at the Hyundai Steel factory, the company says. BMW’s Battery Storage Farm, in Leipzig, Germany, was unveiled last October. Hundreds of used batteries taken from BMW i3 cars and housed at the large system store energy before it is fed into the grid.
I often get asked how such massive batteries can be recycled. To get the answer, I contacted Tesla’s engineering group. Here’s what it had to say.
Tesla’s lithium-ion battery recycling process involves these steps, according to the company. When a Tesla product is decommissioned, it is transported to a company disassembly facility. Batteries are discharged to a low state-of-charge, and modules are removed from the packs. Some valuable components are removed for recycling by qualified employees. Modules are then packaged for shipment to two North American recycling processors in accordance with shipping regulations. At the processing facility, modules are rendered inert and deconstructed. Constituent metals are recovered in separate processes.
Tesla modules are composed of small cylindrical form factor cells, similar to the cells used in many laptops and consumer electronics. The company’s lithium-ion batteries do not contain heavy metals such as lead, cadmium, or mercury. The materials recovered from Tesla modules include nickel, cobalt, copper, aluminum, steel, and lithium. These output products are further refined and used in new applications.
If disposal is required without return to Tesla, entire battery systems can be recycled by a lithium-ion battery recycling facility. A number of North American recycling processors are able to deconstruct large format battery packs, much like Tesla products.
IEEE Senior Member Qusi Alqarqaz is an electrical engineer with more than 28 years of experience in the power industry. He writes about technology, works as a consultant, and mentors younger engineers and students. He is a contributor to The Institute as well as the Analog, a newsletter for the IEEE Central Texas Section. He previously worked in Qatar and the United Arab Emirates.