Promession is a concept for disposing of human remains by way of freeze drying, invented by Swedish biologist Susanne Wiigh-Mäsak.

Promession is based on five steps: The body is first frozen by immersion in liquid nitrogen, which makes it brittle. The frozen remains are then vibrated so that they shatter. The remains are then subjected to a vacuum so that the ice sublimes and the powder becomes dry, and weighs 50-70% less than the original body. Any metals (tooth amalgam, artificial hips, etc) are then removed, either with a magnetic process or sieving. The dry powder is then placed in a biodegradable casket which is interred in the top layers of the soil, where aerobic bacteria decompose the remains into humus, or compost, in as little as 12 months.

The advantages of Promession over cremation are that there are no polluting direct emissions to the atmosphere, whereas cremation usually uses fossil gas (Methane, CH4) and releases Carbon Dioxide (CO2), oxides of Nitrogen (NOx) and mercury vapour from dental fillings. Compared to ‘normal’ burial, Promession should not release CH4 as the decomposition is aerobic, whereas in a deep grave, conditions are anoxic and aerobic decomposers would not survive. Traditional burial may also release liquids into the soil and groundwater, whereas Promession would not. Promessed remains are effectively recycled into soil.

Promession has not been made available commercially yet, as Wiigh-Mäsak is still developing the concept, but there is interest from around the world.

“Promession” is derived from the Italian word for “promise” (promessa).