Alkaline Hydrolysis vs. Cremation: A Full Comparison

The basics of each process

Flame cremation uses intense heat — typically 1,400–1,800°F — to reduce the body to bone fragments over roughly two to three hours. Alkaline hydrolysis, also called water cremation or resomation, uses a heated solution of water and potassium or sodium hydroxide inside a pressurized vessel to achieve a chemically similar end result through an entirely different mechanism. Both ultimately leave behind bone fragments that are processed into a fine powder and returned to the family, but the process to get there differs significantly.

Process comparison

Flame cremation relies on direct combustion at very high temperature. Alkaline hydrolysis instead heats the body in a water-and-alkali solution to between roughly 200–300°F (depending on whether a high-pressure or low-pressure system is used) for several hours, breaking soft tissue down at the molecular level rather than through burning. The liquid byproduct from alkaline hydrolysis — composed of amino acids, peptides, sugars, and salts — is sterile and is typically released into the municipal wastewater system in accordance with local regulations, similar to how other approved effluents are managed. Flame cremation, by contrast, produces combustion emissions released through a flue, including trace mercury from dental amalgam.

Environmental comparison

Alkaline hydrolysis providers and independent researchers generally report meaningfully lower energy use and greenhouse gas emissions compared to flame cremation, since it doesn't require burning fossil fuels to reach cremation temperatures and avoids releasing combustion byproducts into the air. Both methods avoid the land use, vault materials, and embalming chemicals associated with traditional burial, putting each ahead of conventional burial on that specific dimension.

Cost and availability

Cost is generally comparable between the two methods where both are available, though alkaline hydrolysis facilities remain far less common. Flame cremation is broadly available nationwide and internationally. Alkaline hydrolysis is legal for human remains in roughly half of U.S. states as of recent counts, as well as in Canada and parts of Europe and Australia, but licensed facilities lag behind legal authorization in many regions — families may need to work with a funeral home that partners with a provider in another area.

Which to choose

Families drawn to a lower environmental footprint, where available, often lean toward alkaline hydrolysis. Families who prioritize broader availability, familiarity, or the traditional imagery associated with flame cremation often choose that route instead. Both are legitimate, established or emerging choices — neither is inherently more appropriate than the other, and the right decision depends on personal values, regional availability, and family preference.

Frequently Asked Questions