Sometimes it is best not to ponder the future, not to ponder a world where a self-centered species has squandered a planet’s resources and in the process glutted the environment with fossil-fuel derived carbon emissions. Instead today we imagine a world in which the collective will has determined that alternatives to fossil-fuels are required. In particular, today we focus on the generation of electricity with no net carbon emissions.

Electricity generation accounts for approximately 40% of humanity’s energy consumption, the vast majority of it from fossil-fuel burning, carbon spewing technologies. But an array of technologies, some old and some new, may soon change the calculus of electricity.

Hydropower. The power of water falling from up high can scarce be missed at natural wonders such as Angel Falls in Venezuela, the world’s tallest waterfall, or Niagara Falls, the most powerful falls in North America. The creation of dams and hydroelectric power plants supply almost 20% of the world’s electricity and requires no fossil-fuel. However, most obvious sources of hydropower have been tapped. New locations are likely to be more difficult and more costly to develop. Furthermore, hydropower is an old technology, existing for hundreds of years around the world in the form of water mills. Further improvements in efficiency are not likely to be profound. Also, the creation of man-made lakes backing dams has a profound environmental impact in terms of displacement of populations, effects on numerous species of wildlife, and emissions from decomposing biomass in reservoirs.

Nuclear. Is nuclear a dirty word? Can the world get over 3 Mile Island, Chernobyl or the next lurking disaster? Are more reactors a bulls-eye for terrorists? Would you want one in your neighborhood? Overall, nuclear energy supplies around 15% of the world’s electrical energy. Uranium is ample and relatively cheap. Energy output is reliable and suitable for sustaining power grids. Really, nuclear energy is quite clean. Until there’s an accident, of course. Or until you need to dispose of spent fuel and other really, really undesirable waste. If you follow the drawn-out wrangling regarding the Yucca Mountain nuclear waste repository, you’ll begin to realize that nuclear energy is not likely to be a strong contributor to US energy supplies in the near future. The future of nuclear energy is more promising in regions with a more opaque political process; almost all of the new reactors being built are in Asia. As for me, not in my backyard.

Biomass. There’s nothing simpler than burning wood. Or crop residue. Or other stuff grown from the ground that burns. As a local solution for heating and cooking this is very viable, and more recently so for generating electricity, often as a supplement to coal or gas in conventional electrical plants. The downside of biomass is costly transport and the resulting necessity of linking available biomass to a nearby power plant. But if carbon neutral is your mantra, you can’t beat biomass. Plants capture carbon from the environment then give it up again when burned. Nice and sort of clean. Of course, growing plants for fuel diverts arable land from other endeavors, like feeding people.

Wind. Wind is the most rapidly growing source of alternative energy. The US added 5.3 gigawatts of wind capacity in 2007, which is 35% of all new energy capacity added in the country. The most important advance is the declining cost of installing wind turbines, making it in some cases competitive with coal. It is really, really clean, requiring no fossil-fuel whatsoever and giving off no carbon. But you can’t make the wind blow. Lack of reliability makes wind power on its own unsuitable for sustaining a power grid. Also, if you have ever admired the sculptural line of a wind turbine, imagine several hundred of them obscuring your view of the ocean. Many locations with desirable wind conditions are preferred pristine by those that live there. And of course there is the law of unintended consequences. Harness enough wind power and a butterfly somewhere will flap its wings. It is speculated that large wind farms can produce warming of downwind areas, as the cooling benefit of the wind is sapped.

Solar. Who says that you can’t improve on Nature? Today’s photovoltaic panels can convert greater than 15% of solar energy into useful electricity. A leafy plant of the green variety—around 1%. Solar energy is perfectly clean and it just feels so natural. It’s sort of back to basics. Everything comes from the sun…electricity too. And solar cells look cool and do not aggregate to quite the eyesore of a wind farm. But solar cells are also unreliable. Night, clouds and day-to-day variability make them unreliable for powering grids. Thermal technologies that couple solar energy to a working medium help solve this problem by storing energy. Distributed storage in batteries is another possibility. Overall, solar is a shining star of alternative energy, with plummeting costs driving demand. You can also add them easily to your own home or business. Try that with a hydropower plant. Although solar energy is not yet competitive with coal on a kilowatt-hour basis, when compared with the retail cost of electricity, it can be quite efficient on a small scale basis. But large installations will require wide open sunny areas, such as a desert, creating issues of distributing that power over distance. Nevertheless, the price of solar power is expected to fall in the future, possibly by an order of magnitude. Unlike mature technologies such as hydropower, solar energy is in its infancy.

Other. In an era of $4+ gas and whopping home electric bills, many eyes turn to the development of alternative and sustainable energy. Other possibilities not discussed are geothermal energy, harnessing the heat deep in the Earth, and tidal and wave power utilizing the might of the ocean. Of course, you can also modify your Zigo Leader or bicycle to be a pedal generator. See this article from Mother Earth News for some inspiration.

Let’s all just hope the sun doesn’t burn out.

Change your life. Change the world. Zigo.