Over the past twenty years there has emerged widening interest in shifting to a lower carbon world. This has primarily been motivated by fears of human-induced climatic change, growing risks to sustainable development, concerns about the continuing availability and affordability of useful energy, and opportunities for investment gains. Promotion of renewable forms of energy, and related technologies, has been considered the way forward, for understandable reasons. But some major challenges have been overlooked, sidestepped, and/or sometimes denied on spurious grounds - examples can be noted in biomass, biofuel, wind, solar, and estuarine barrage or tidal lagoon schemes, for example. Technologies are proposed and discussed which may, and hopefully will, assist in meeting the various challenges, but such proposals and discussions often exhibit excessive optimism about likely transition times and scale of contribution. Already massive subsidies provided or supported by many industrialised country governments to foster renewable forms of energy have had major impacts on electricity prices, fuel poverty, and cut-offs of domestic supplies. Further down the line, the relatively low power densities of renewable forms of energy, their relatively poor energy returns on energy invested (EROI), and a tendency to overstate emissions reductions (by not including emissions 'embedded' in imports), will bring increased realisation that there may not be "a fantastic evolution just ahead of our time", as has been claimed.