Renewables Facts Flashcards
What are REEs?
Rare-earth elements
Which REEs are crucial for the production of solar, wind and electric vehicles, among other electronic products?
Nd - Neodymium
Dy - Dysprosium
Pr - Praseodymium
Tb - Terbium
How are REEs extracted?
Dilute concentrations requires millions of tons of harsh chemical acids such as sulfuric acid, gluconic acid and phosphoric acid are used to wash through ores, containing trace amounts.
How many tons of REEs are produced worldwide?
As of 2018. about 175,000 tons, mostly in China.
Who are some of the leading manufacturers of large modern wind turbines?
Leading manufacturers of large modern wind turbines include Siemens Gamesa Renewable Energy and MHI Vestas Offshore Wind.
What part of the turbine requires rare earths, and which ones?
The permanent magnet generators in advanced offshore wind turbines use neodymium-iron-boron (NdFeB).
Are there any substitutes for Nd (neodymium)?
Yes, to reduce production costs and improve the performance (particularly for higher temperatures), some neodymium (Nd) is substituted by other rare earth elements such as praseodymium (Pr), dysprosium (Dy) and terbium (Tb).
What is the rare earth element content of NdFeB magnet by weight?
The total rare earth element content of a NdFeB magnet is typically about 32% by weight, with Nd and Pr typically accounting for about 30% and heavier rare earth elements accounting for about 2% weight, depending upon the grade.
What are pro’s and cons of permanent magnet synchronous generators?
These allow more efficient and reliable operation but the downside is high capital costs, with magnet prices ranging from $75 to $150 per kilogram, which adds up for large machines that require several tons worth of permanent magnets.
What were the alternative wind designs replaced by permanent magnet synchronous generators?
Doubly-fed induction generators (DFIG) and conventionally wound rotors, which were subject to frequent slip-ring/brushes failures and losses.
What are some of the production challenges of wind turbines?
The assembly process of large permanent magnet generators can be challenging, with extremely strong magnetic fields acting on one another. The magnets themselves need to be treated for protection against corrosion and fixed securely to the rotor (depending on the technology) to avoid becoming loose and damaging the machine.
Can rare earth magnets be “recycled?”
Yes but the process is quite lengthy and involves demagnetization (by heating), crushing and roasting, followed by a leaching process and a separation method before a final roasting to produce a mixed rare earth oxide.
What’s the distribution of REEs?
China has some of the most significant concentrations of rare earths in the world including the Bayan Obo mine in Inner Mongolia, about 36% of supplies. Russian Commonwealth nations have 19%, the United States has 13% and Australia has 5% of the rare earth reserves.
Which countries have managed to mostly de-carbonize their energy usage without nuclear?
A few lucky countries with abundant hydroelectricity, like Norway and New Zealand, have decarbonized their electric grids, but their success cannot be scaled up elsewhere: The world’s best hydro sites are already dammed.
Which countries have de-carbonized without impacting economic development or quality of life?
France and Sweden. They decarbonized their grids decades ago and now emit less than a tenth of the world average of carbon dioxide per kilowatt-hour. They remain among the world’s most pleasant places to live and enjoy much cheaper electricity than Germany to boot.
