Dry ice is the solid form of carbon dioxide (CO2), so it is not possible to make dry ice without CO2. The process of producing dry ice involves pressurizing and cooling gaseous carbon dioxide until it becomes a solid at a temperature of -78.5 degrees Celsius (-109.3 degrees Fahrenheit) under normal atmospheric pressure.
Carbon dioxide exists naturally as a gas in the Earth's atmosphere, and it is commonly produced as a byproduct of various industrial processes, such as the combustion of fossil fuels or fermentation. To obtain dry ice, the gaseous carbon dioxide is typically compressed and then rapidly cooled, causing it to solidify into the form of dry ice.
If you are looking for alternatives to dry ice for a specific purpose, it would be helpful to know the specific application or desired outcome you have in mind. Depending on your needs, there may be other substances or techniques that can achieve similar effects, but they would likely differ from the properties and characteristics of dry ice.