For searching the web using Forestle is also essentially CO2-neutral : Of course the server computers used by Forestle , the connection network , and the computer of the searching users need electric energy and thus create emissions of carbon-dioxide ; but Forestle purchases an equivalent amount of renewable energy certificates . A Forestle search is also essentially CO2-neutral , as Forestle.org offsets the carbon-dioxide emissions caused by electricity consumed by all Forestle servers , the network infrastructure as well as the computers of each user by purchasing an equivalent amount of renewable energy certificates .