Hydrogen Powered Flames for the Tokyo 2020 Olympic Cauldron

When Japanese tennis star Naomi Osaka lowered the flame into the Olympic cauldron symbolically signalling the opening of the Tokyo 2020 Olympics Games, all attention was on the Cauldron designed by Nendo.

The dynamic, white structure was designed to reflect the Japanese design and building capabilities by Nendo founder Oki Sato to pass on the message of the opening ceremony’s concept of “All gather under the sun, all are equal, and all receive energy”.

This concept was coined by Mansai Nomura, who was the Chief Executive Creative Director of the planning team for the opening and closing ceremonies at the Tokyo 2020 Olympics and Paralympics.

“Through trial and error, a spherical form was designed, consisting of upper and lower hemispheres each with five panels representing the Olympic rings. At the end of the Opening Ceremony of the Olympic Games, the cauldron bloomed to welcome the final torchbearer. The design was a comparison to not only to Sun but also the energy and vitality that can be obtained from it, such as plants sprouting, flowers blooming, and hands opening wide toward the sky,” says Oki Sato.

Keeping with the Tokyo Olympics’ intent to keep the Games a sustainable one, every resource has been used from facilities close by with materials that are more sustainable. The flames were fuelled by hydrogen energy that was produced at a facility in Fukushima Prefecture, which is undergoing recovery from the Great East Japan Earthquake that occurred in 2011. The electricity required for the electrolysis of water in the hydrogen production process was through solar power generation. Since hydrogen burns with a colourless and transparent flame, it was necessary to be coloured as it had to be seen when used as the Olympic flame. Sodium carbonate was used for the “yellow” flame.

“The amount and direction of the aqueous solution sprayed from the vicinity of the burner were repeatedly examined along with the amount of hydrogen and the angle of the valve, in order to adjust the movement and shape of the flame to shimmer just like firewood was stoked,” says the creator adding that such an attempt to “design flames” was never tried before.

The cauldron weighs 2.7tonnes, and the diameter after transformation is about 3.5m. The exterior panel, which weighs approximately 40 kg per sheet, was made by cutting out a 10 mm thick aluminium plate; moulding it with a special hot press machine capable of applying a pressure of 3500 tons, which only a few exist in Japan; and then milling it. Since distortion occurs when heat is applied during milling, the work was performed at ultra-low speed while consistently scanning the shape using laser, shaping up to 7 mm thickness where strength is required, and down to 4 mm where strength is not required, to accommodate weight reduction. The last phase consisted of adjustments, polishing, and application of heat-resistant paint, all of which were finished by the local craftsmen.

The internal drive unit was required to be as compact as possible, yet highly waterproof, fireproof, and heat resistant. By covering the machines with polygonal mirror panels as much as possible, it was intended to create a diffused reflection of the light from the ceremonies and the flamelight. Tests for heat resistance and wind resistance were repeated, and the apparatus was tuned to prevent any vibration or error even under varying conditions. As a result, a smooth movement with fine accuracy in panels passing each other was realized, operating at less than 3 mm distance at the area of narrowest passing width.

 “The Olympic cauldron created through this journey, is a standing testimony to the essence of Japanese manufacturing,” says the designer.

All Images Courtesy Nendo