In an electric tandoor there is no open flame, so the plate will not produce CO2. This may seem like the greenest option, but sadly it's not that simple! If the electricity that powers the grid was produced by fossil fuel-fired power plants, they would have produced a lot of CO2 and caused environmental damage. However, if the electricity was generated from renewable sources, such as wind or photovoltaics, then little CO2 will be produced.