Cows fart Methane. We can take advantage of this Methane and use it for multiple things including the production of electricity.
Methane is a chemical compound with the formula CH4 that is found in nature (one carbon atom bonded to four hydrogen atoms). It's a group-14 hydride, the most basic alkane, and the most abundant component of natural gas. According to clear.ucdavis.edu, the greenhouse gas methane is produced when grass and other plants (what cows primarily eat) digest in the cow's rumen. The cow then either farts or burps this Methane, and it's released into the surrounding air. The methane would be transferred to a contained environment where it would be burned so the byproducts could be captured and stored. Learn how exactly this process works on the next paragraph.
As long as the machines being used in this process are extremely precise and accurate, you will be able to, from the Methane released by the cow(s), generate some electricity for you to utilize, get some water vapor and let it condense to water the plants which the cows eat, and capture the CO2 (a byproduct of Methane when burned) and use it for the plants, allowing them to breathe. You may also use some of the water for drinking (for both cows and humans). In the process, you'll first capture the Methane which the cows fart. Then you'll burn it in a contained environment. After burning it (in a CH4/O2 rich environment), you'll. be left with gaseous H2O and CO2. From there, you can use the H2O to water the plants and to let the cows drink, and you can use the CO2 to let the plants breathe, since they breathe CO2. More plants will now grow (assuming you planted more) and will thrive, further sustaining the lives of the cows, producing more Methane to be used for electricity and water. Some of the plants grown could also be eaten by humans.