Siemens Gamesa (the companies’ 2017 merger reflects other mergers in the sector, Huang noted) has 75 GW of capacity installed worldwide and employs 27,000 people. He stated that offshore wind power is “the frontline of technology advancement.” Two trends are emerging to produce more wind energy at lower costs: (1) larger turbines and (2) smarter turbines that use sensors to respond to conditions and communicate with each other.

Huang described his company’s efforts to develop larger wind blades at its Boulder, Colorado, Research & Engineering Center. The three blades of a turbine under development, known as the SWT 8.0-154, each have a length of 75 meters, a width of 5 meters and a rotor diameter of 154 meters. A blade weighs 25 tons (the equivalent of 16 mid-sized cars); and a rotor swept area is equivalent to 4.5 football fields. One issue is the time-consuming manual blade construction in which glass fabric is applied to a mold at a rate of 2,300 pounds of glass every hour, yielding one blade per day.

Increasing the size of a rotor is directly proportional to power generation, he explained, but the square-cube law challenges this aim: that is, for a rotor to double in power, it has to triple in volume. How can rotor size increase without becoming too heavy (e.g., a 50 ton blade is too heavy to fly)? Technology advancement attempts to defy the square-cube law through better aerodynamics (for example, curved rather than straight blades), higher-quality manufacturing processes, and stronger glass-carbon hybrid materials. Blades are in development with stiffer and lighter fibers, fatigue-resistant and low-viscosity resins, lighter core materials, and thicker laminates.

Huang pointed to the issue of recycling as wind turbines move out of service over time. What to do with these materials relates not only to wind, but also to other alternative energy technologies. In the case of wind, from 2010 to 2014, the equivalent of 212 GW of wind energy was installed, or about 450,000 blades using 2 million tons of composite materials. What will we do with the materials once they are done providing sustainable energy? Innovative alternative uses to these massive blade are needed, Huang concluded.

Energy Mass Storage Technology Advancement

According to Jay Whitacre, professor of materials science and engineering and engineering and public policy at Carnegie Mellon University, energy storage technology is not as fleshed out as solar and wind, although it has existed in some form for more than 100 years. Lithium-ion batteries, the current dominant form, have been used for about 30 years.

Whitacre focused on the creation of electrochemical energy storage (other types include pumped hydro, thermal, and ice storage), which must have two separate, coexisting systems. This is a very materials-intensive technology. Unlike wind and solar, which have a few dominant technologies, many energy storage technologies continue to vie for market share. It is not clear which type will dominate economically, making decisions difficult.

Whitacre’s lab and others attempt to decrease the cost per kWh for lithium-ion batteries, but the capital cost per kWh is not a useful metric without much more information on use-case and degradation. A variety of needs are required: to understand how long a battery will last, how many duty cycles it can accommodate, and the value placed in any given application. The lack of a good baseline confounds the industry because there is no good way to evaluate options.

Two main types of lithium-ion batteries are now produced, with cylindrical and prismatic cell formats. Both require a spectrum of major industrial chemicals, precious metals, and rare earth elements, and there is no dominant single material with the aim of cost optimization. Whitacre added that cobalt has had a dramatic increase in price and decrease in availability in the past year while the most scaled energy storage materials systems are not materials optimized. The complexity of the manufacturing process, which consists of 16 separate steps, also makes it hard to find ways to use less energy or materials.

A 2013 study by a group from Stanford University compared ratios of total electrical energy stored over the life of a storage technology, Whitacre said.6 Compressed-air and pumped-hydro batteries had the highest efficiency. Lithium-ion batteries were far less energy-efficient; lead-acid batteries, the most commonly used energy storage system today, fared even worse. Yet more robust batteries typically cost more, and some end uses do not call for the more expensive options, even if they are more efficient.

Recycling energy storage batteries is difficult because the different materials are closely wound together, making separation complicated. Whereas some valuable minerals could be recovered (such as cobalt and nickel), there are not enough units to justify the disassembly and re-segregation needed. To illustrate the complexity, Carnegie Mellon launched a company called Aquion Energy in 2009 to create a sustainable product. In the process of being purchased after suffering downsizing at the time of the workshop, the company’s recent setback illustrates the commercial challenges in creating cradle-to-cradle energy storage. Whitacre concluded his presentation by stating that more sustainable energy storage systems would require less processing of materials before insertion, aqueous-based electrolytes, high tolerance to lower purities, and very long lifetime/cycles.

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