There is no combination of energy sources that can replace fossil fuels (see Energy in a Nutshell for details). We're going back to the age of wood. This is bad news, but when you know a hurricane is approaching, you put up storm shutters -- you don't endlessly debate whether hurricanes exist or not.
The approaching ecological storm is a "Limits to Growth" confluence of over-exploitation of our natural resources: depleted aquifers, fisheries, forests, and topsoil, toxins in our air, water, and soil -- all of these at a crisis point already -- but with cheap and plentiful energy hiding the fact that the hurricane is much closer than it appears. The descent of energy is the tipping point of western civilization into collapse.
The time to have begun planning and bringing world population into line with the carrying capacity of a wood-fueled civilization should have begun in the seventies, when we had our first wake-up call during the oil shocks of 1973 and 1979. So this is going to be one hell of a hurricane, but less so for those who prepare now. Here are some of the things that can be done:
1) There are several groups dedicated to finding solutions, two of the best are Community Solutions and the Post Carbon Institute. If there isn't already a local peak oil group in your town, start one. Several communities have begun planning for energy descent in Tompkins county (NY), Kinsdale (Ireland), and Willits (CA). Every community is unique and has different issues depending on the climate, soil, transportation infrastructure, and so on, as you'll see if you contrast Cuba's situation with Oakland, California.2) Educate yourself and your community. Here's a list of the best books and articles on energy and related topics. If you can't see .xls files, select this book list.
3) You can help prevent World War III over the remaining oil fields by talking with your local politicians and business community about the Oil Depletion Protocol.
4) Currently agriculture is utterly dependent on fossil fuels, there needs to be a very quick "back to the land" movement, hopefully of small family farms using bio-intensive techniques. If this doesn't happen, it's likely the end result will be feudalism, rather than the Jeffersonian ideal of small family farms.
5) Preservation of Knowledge: There is a real risk of a dark age after the ecological collapse. We should think about how to preserve knowledge now while we still have cheap and abundant energy.
Alice Friedemann in Oakland, California