Green cremation is a water-based process that breaks down the body using a heated alkaline solution instead of fire. Technically called alkaline hydrolysis, it goes by several names: aquamation, water cremation, or bio-cremation. The result is the same as flame cremation (bone fragments processed into a fine powder for the family), but it uses roughly 90% less energy and produces no direct air emissions.
How the Process Works
The body is placed in a stainless steel vessel filled with hot water and an alkaline solution, typically potassium hydroxide, sodium hydroxide, or a mix of both. The vessel is pressurized and heated to between 100 and 150 degrees Celsius, depending on the system. Over the course of 3 to 16 hours, the combination of heat, pressure, and alkalinity accelerates the same chemical breakdown that happens naturally in soil, just far faster. The process dissolves soft tissue completely, leaving only bone fragments and a sterile liquid.
The bone fragments are dried, processed into a white powder, and returned to the family in an urn, just like traditional cremation. Families typically receive about 20% more remains than they would from flame cremation, because fire doesn’t consume some of the calcium phosphate that alkaline hydrolysis preserves.
What Happens to the Liquid
The liquid left behind, called hydrolysate, is a sterile mixture of amino acids, basic sugars, and dissolved minerals. Before disposal, it’s neutralized to lower its pH, sometimes using carbon dioxide bubbling or dilution. Once treated, it can be safely discharged into standard municipal wastewater systems. Facilities need to coordinate with local water treatment plants to make sure the downstream infrastructure can handle the organic content, nutrients, and ammonia levels in the effluent.
Environmental Advantages Over Flame Cremation
Traditional cremation burns natural gas at roughly 760 to 980 degrees Celsius for one to three hours, releasing carbon dioxide, particulate matter, and vaporized mercury from dental fillings directly into the atmosphere. Mercury is particularly concerning: dental amalgams become unstable at cremation temperatures of 650 to 700 degrees Celsius, causing the mercury to volatilize and escape into the air.
Green cremation eliminates these direct emissions entirely. There’s no combustion, so no CO2, mercury vapor, or particulate matter leaves the facility through a smokestack. The energy savings are significant too, with the process using about 90% less energy than a flame-based system. For people choosing cremation partly for environmental reasons, alkaline hydrolysis addresses the biggest ecological drawbacks of the conventional approach.
How It Handles Medical Implants
One practical advantage of green cremation is how it deals with medical devices inside the body. In flame cremation, pacemakers pose a real danger. They can explode at high temperatures, putting crematory staff at risk. Orthopedic hardware like hip and knee replacements survives the fire but must be separated from the ite remains afterward.
With alkaline hydrolysis, there’s no explosion risk from pacemakers or other battery-powered implants because the temperature stays far below combustion levels. Metal implants, screws, and joint replacements simply remain intact in the vessel and are easily removed after the cycle. Dental amalgams don’t volatilize in the lower temperature range, so mercury stays contained rather than entering the atmosphere.
Cost Comparison
Green cremation costs roughly $1,700 to $4,500, compared to $1,000 to $4,000 for traditional flame cremation. The price difference is modest, and both options cost considerably less than a standard burial, where the casket alone can run as much as the entire cremation process. Pricing varies by region and provider, and in states where only one or two facilities offer the service, the limited competition can push costs toward the higher end of that range.
Where It’s Legal
Alkaline hydrolysis is currently legal in 28 U.S. states. In many of those, facilities are actively operating and accepting families. States like California, Florida, Illinois, Oregon, Washington, and Minnesota all have providers offering the service. Other states, such as Idaho, Kansas, Maryland, Vermont, and Wyoming, have legalized the process but don’t yet have facilities in operation, meaning residents would need to work with a provider in a neighboring state.
Some states, including Colorado, Georgia, Maine, and Missouri, allow the process without an explicit statute, operating in a regulatory gray area where it isn’t specifically prohibited. The legal landscape has been shifting steadily, with Hawaii being one of the more recent additions in 2022. Legalization efforts in the remaining states often face opposition from the traditional funeral industry and, in some cases, from religious groups with concerns about the process.
What to Expect as a Family
From a family’s perspective, the experience is nearly identical to arranging a traditional cremation. You work with a funeral home that offers the service, choose an urn, and receive the processed remains within a few days. The remains look and feel similar to those from flame cremation, though slightly lighter in color and greater in volume. They can be scattered, kept in an urn, or placed in a columbarium just like conventional cremated remains.
The main logistical difference is availability. Because the process takes 3 to 16 hours per cycle (compared to one to three hours for flame cremation), facilities may have longer turnaround times, particularly smaller operations with a single machine. If you’re in a state where no local provider exists, some funeral homes will arrange transportation to a facility in another state, though this adds cost and time.