I agree that the only hope is through better technology, and I'm somewhat hopeful that these can be developed. Imagine how much better life on our planet might be if we could just harness the power of the sun, wind, or waves in ways that were financially feasible. Much progress has been made, and I suspect that much more will be made. When I come home each night, a very bright solar-powered light switches on and illuminates the outside stairs for me. I hope we can make a quantum leap soon in developing some of these technologies.
We won't ever destroy the Earth. The Earth will rid itself of us long before we come to that. Mother has existed long before Mankind, and she'll exist long after we're gone. The real question is the destruction of ourselves.
I would have to agree with Pohnpei's comment. We have come to a point in our society that we need to be able to sustain our current pace of life in order to do what needs to be done. The more efficient we become, the more is expected of us. If we were somehow required to stop doing things in order to use less energy, we wouldn't be able to stustain our current way of life and things might collapse. With that said, we MUST find a way to use less energy because, eventually it will go away. It may not be soon as many doomsday predictors think, but I believe any logical person has to believe that our energy will run dry eventually. So the question becomes, how do we continue our fast-paced lifestyle while consuming less energy? The answer probably lies, as Pohnpei says, in technology. If we can harness solar power and wind power, for example, we will have an energy source that won't go away for a long time.
So the question is how do we "do them in as sustainable a way as possible?" i would argue that the way to protect the Earth is through technology. We need to create new technologies that will allow people to have the same standard as living they now have but without using as much energy.
There are many human activities that won't necessarily destroy the Earth, but will certainly make it more difficult for us to live on it. Carbon emissions are an obvious example, but other activities, including deforestation, mineral extraction, and water pollution by industry, agriculture, and household activities as well as overconsumption threaten our standard of living. Ultimately, all these activities are in varying degrees unavoidable, and the trick is to figure out ways to do them in as sustainable a way as possible.