Tesla is arguably one of the most dynamic companies in the industry today, with its tendency to constantly innovate even after it reaches its ambitious targets. This particular culture was mentioned by Tesla’s President of Automotive Jerome Guillen in a recent interview with CNBC, when he stated that Tesla’s work, specifically in its batteries, continue to evolve over time. Elon Musk echoed this tendency on Twitter, stating that even Tesla’s vehicles like the Model S and X are partially upgraded every month “as soon as a new subsystem is ready for production.”

Such a culture is emblematic of Tesla. Such a culture is also reflected in a recently published patent for the company, which outlines a clever waste water treatment system that could pave the way for more cost savings in operational expenses. The patent is titled System for Regenerating Sodium Hydroxide and Sulfuric Acid from Waste Water Stream Containing Sodium and Sulfate Ions and was published on November 15.

Tesla notes in its patent description that “acid leaching performed through the addition of sulfuric acid and neutralization through the addition of sodium hydroxide” are common processes used in manufacturing. As a result of these processes, waste water containing high concentrations of sodium and sulfate ions produced, since sodium and sulfate ions are very soluble and are difficult to remove through conventional precipitation processes. Tesla notes that these factors could result in large quantities of waste water being disposed — a process that is both expensive and harmful for the environment.

In a conventional waste water treatment setup, three chambers separated by an anion exchange membrane (AEM) and a cation exchange membrane (CEM), as well as anodes and cathodes, are utilized. Tesla notes that the present system for waste water treatment leaves much to be desired, considering that the setup is not cost-effective at all.

“With the prior art system, not all of the sodium and sulfate ions are able to be removed from the waste water feed stream to produce the ‘treated’ water. This reduces recovery of acid/caustic, and also presents challenges when trying to reuse the “treated” water. This process becomes increasingly difficult as the concentration of ions in the waste water feed stream lowers as it moves through the electrolysis treatment system, and an increasing amount of electrical voltage needs to be applied.

“Further, the generated acid/caustic products can only be produced at low concentrations. As the product streams increase in concentration, an increasing amount of electrical voltage is needed between the anode and the cathode. Further, as the membranes AEM and CEM are in contact with these higher concentration acid/caustic products, the lifetime of the membranes and decreases. The combination of a high electrical load, low recovery efficiency, low recovered acid/caustic concentrations, and short component lifetimes make the prior art system economically unviable.”

Advertisement

Tesla’s waste water treatment system utilizes membrane concentration systems as a cornerstone to develop a system where waste water is treated and possibly even reused. The electric car maker describes its system in the following description.

“As compared to prior waste water treatment systems, the waste water treatment system of the present disclosure uses the three dedicated membrane concentration systems to maintain high ion concentrations in the feed and low ion concentrations in the product chambers. The first thermal concentration system takes in the dilute acid produced by the electrolysis treatment system that allows pure water to permeate while the dissolved acid species are rejected. The pure water is recycled back to the second chamber of the electrolysis treatment system to dilute this stream, while the reject concentrated acid is extracted as a product.

“The second thermal concentration system takes in the dilute caustic produced by the electrolysis treatment system and allows pure water to permeate while the dissolved caustic species are rejected. The pure water is recycled back to the third chamber of the electrolysis treatment system to dilute this stream, while the reject concentrated caustic is extracted as a product. The membrane concentration system takes in the existing waste water that still contains significant dissolved sodium and sulfate. Pure water is extracted as a product, and the concentrate reject is sent back to the electrolysis treatment system waste water feed to maintain a high concentration of sodium and sulfate ions in the waste water feed.”

With such a system in place, Tesla expects to see optimizations in its operations. The Silicon Valley-based carmaker noted in its patent that its waste water treatment system would likely even extend the lifetime of components such as the AEM and CEM, resulting in more cost savings.

“The waste water treatment system of the present disclosure has significant operational advantages, including resulting in large positive driving concentration gradient assisting electric voltage, as opposed to negative gradient resisting electric voltage in (a) conventional system, dramatically reducing electrical load. The waste water treatment system allows for the AEM and CEM of the electrolysis treatment system to be in contact with low concentration acid/caustic, significantly increasing their lifetimes.

Advertisement

“Further, the produced acid/caustic from the membrane concentration systems are at much higher concentrations than the electrolysis treatment system could make on its own, increasing their value. Moreover, the exiting pure water product is Reverse Osmosis (RO) quality and can be directly used to service pure water needs. The recovery of both sodium and sulfate ions is near 100%, since there are almost no remaining ions in the exiting pure water product.”

Over the past months, published patents from the company show that Tesla is looking to optimize several aspects of its operations. Included among these is a rigid structural cable that could open the gates for more automation, a flexible clamping assembly that would allow the company to easily address panel gaps, as well as a DCM recovery system that could make battery manufacturing safer.

Tesla’s recently published patent for its novel waste water treatment system could be accessed in full here.