The best replacement for co2 is compressed air.

The best alternatives to co2 are rated as following:
★★★★★  compressed air
★★★★  hpa
★★★  green gas
★★★  temperature
★★  co
★★  nitrogen
★  air
★  c02
★  n2
★  bho
★  compressed air for paintball
★  pco2
★  o2
★  temperature graph
★  pump
★  carbon monoxide
★  butane
★  temperature chart
  nitro
  co2
  hand pump
  methane
  fiber laser
  no2 boiling point
  argon
  compressed air paintball
  nitrogen paintball
  yag laser
  temp
  fraxel
  electric airsoft
  sio2
  hco3
  temp graph
  methane greenhouse gas
  gas airsoft
  no2
  spring air rifles
  nitrous
  global warming
  fraxel laser
  pump bike
  so2
  argon mix
  kwh

Your alternative for co2 is not listed? Suggest!
Speaking about co2, one probably shouldn't forget about lime water.

Other search terms related to co2 and their ratings are:
★★★★★ lime water
★★★★ naoh
★★★★ mgbr
★★★ lime water equation
★★★ grignard reagent
★★ water reaction
★ plants
★ air pump
★ hob filter
anti siphon tank
autococker
tank
co2
cannabis
limewater
smart parts ion
ion
You have in mind a companion for co2 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of co2 in all years. Click on graph for more.
co2
compressed air
hpa