I have some years a coffee fully automatic machine from Jura. Now I have tried other ways to prepare coffee, namely Moka pot and Chemex.
I want to keep my electricity consumption as low as possible and wonder which coffee preparation is the most ecological? How do my 3 tried variants compare?
Brewing
Of those three brewing methods, the Chemex should take the least energy when using a microwave oven to heat just the amount of water needed. Microwave ovens are very efficient since nearly all the energy goes into heating the water and (indirectly) the cup holding the water.
In comparison, a Moka pot requires heating the entire pot and its contents over a stove, so a significant fraction of the heat energy goes into the stovetop, pot, and air. Worse, when using a gas stove, it will emit CO₂, unhealthy combustion products, and also some methane when starting and stopping the flame. (Use a hood fan to exhaust most of these gasses.)
An automatic coffee machine has to heat the water and its internal components to the desired temperature, most likely using a resistive electric heater. Even worse if it's in a standby mode that holds the water hot for a long time. I bet energy efficiency is not high on the designers' priority list.
Even better: With an AeroPress you heat just the amount of water needed and heat it to a lower temperature than other brewers. Per the manufacturer's recommendation, 175°F (80°C) or 185°F (85°C). (Or start there and experiment with the brewing temperature to taste.) I set an 1100 watt microwave oven for ≈93 seconds, then stir the water (since the heat rises in the cup). (When I'm really picky, I use a thermometer to wait for it to cool to 175°F.) For the best taste, use "bypass brewing," that is, put 1/4 of the water through the press, stir for 10 seconds, then add rest of the water to the cup.
Best: Use the AeroPress "cold brew" recipe which skips the heating entirely. (I use an under-sink tap water filter.) The cold brew recipe comes out very tasty, esp. on a hot day. Remember to put only 1/4 of the water into the AeroPress, stir for 1 minute, press, then add the rest of the water to your cup.
Grinding
Use a hand grinder if you want to save more energy. It provides good exercise and it won't wake the household. It does take more work and time than an electric grinder.
