When it’s fully complete, Tesla’s Gigafactory in Sparks, Nevada, will be the largest building in the world, sprawling over 15 million square feet on a plot of land more than three times larger than Central Park. The building, which Elon Musk has called “the machine that builds the machine,” will eventually also be the first large-scale battery factory to run on 100% renewable energy. The factory currently makes battery packs and electric motors for the Model 3 car, along with the company’s Powerwall and Powerpack battery storage.
Designing the factory from scratch “provided some great opportunities to rethink manufacturing,” says Rodney Westmoreland, director of construction management for Tesla. “We look at challenges from first principles–breaking things down to the very basics of physics and what’s possible–since we’re doing something that has never been done before. As a result, our teams of mechanical, electrical, and manufacturing engineers have spent the last few years creatively building a sustainably powered facility with no onsite combustion of fossil fuels. This was critical to our mission of moving the world to a sustainable energy future.” A new environmental impact report released on April 15 includes a case study on the factory’s sustainable design.
On the roof–designed to accommodate solar power–a solar installation that is currently underway will eventually include around 200,000 solar panels that can provide most of the building’s energy when paired with Tesla’s batteries. When it’s finished, it will be the largest rooftop solar array in the world.
Inside the factory, high-energy manufacturing processes that would normally be powered by natural gas have been redesigned to avoid fossil fuels by maximizing energy efficiency. Waste heat from equipment like compressors or high-temperature ovens can be used both to run the equipment efficiently and to help keep the factory warm in the winter. LED lights and a lighting system designed to reduce power use means that lighting the building can save 144 megawatt-hours of energy in a month versus traditional lighting setups (the equivalent, the company says, of the energy needed to drive a Model S 480,000 miles).
The company has been working with vendors to find new techniques to make it possible to meet its goals. The process “pushes the general contractors and design-build firms to change the way that they think, hire, and construct,” says Westmoreland. “For example, Tesla engineers partnered with our equipment vendors to look at ways we could reverse-engineer air compressors to handle incredibly [hot] waste heat, which makes our factory and equipment more efficient. These have become solutions that vendors can use throughout the industry.”
Because manufacturing batteries is so energy intensive, the equipment in the factory generates so much heat that it’s necessary to pump chilled water through the building to cool it down–something that normally also takes a huge amount of energy. To solve the problem, Tesla designed a unique chilled water plant that makes use of the desert climate: When the air is cool at night, the plant generates more chilled water than needed, and that extra water can be used during the day. The system, which uses one of the largest thermal storage tanks in the world, will cut electricity used in the process by up to 40%, and cut water consumption up to 60%. “Up front, it seems quite monumental to design, construct, and estimate, but ultimately it eliminates the need for numerous chillers and the amount of energy required to run them,” Westmoreland says.
In parts of the manufacturing process that require dry air, the factory can pull in desert air to reduce the use of dehumidifiers. A heat pump helps power another process that coats part of the battery cell with a solvent. (Liquid waste from the process is also refined and recycled onsite, rather than shipping it to a separate processing center, eliminating the need for 30 tanker trucks a week.)
The company is building the factory in phases so that it can continue improving the design. Right now, though it began mass-producing lithium-ion battery cells in 2017 and started making battery packs and drive units for its Model 3 cars in 2018, the building is only 30% complete. At the moment, as the solar installation continues, it’s also still using power from the local grid. But all of the elements of the factory’s design, and the eventual switch to 100% renewable energy, will help Tesla shrink the carbon footprint of making electric cars. (One study found that building a battery alone, in a factory running on fossil fuel power, makes manufacturing an electric car typically more polluting than making an efficient conventional car.)
The factory’s efficiency also helps reduce cost, and batteries are the most expensive part of electric cars. Other battery manufacturers could follow Tesla’s example. “We believe Gigafactory could be a blueprint for a more sustainable construction industry,” Westmoreland says. “When Tesla decided to create a net-zero initiative for the completed facility, we took it seriously. We care as much about the sustainability of our products as we do the way we build them.”