I love it when a plan comes together. Jon asks, what are the most viable alternatives?
That is not such an easy question to answer, but I'm anxious to give it a shot.
First, what are not viable alternative energy sources? Hydrogen!! I know you've all heard the hype. Hydrogen is the most plentiful element on earth. The only exhaust from its burning or conversion in a fuel cell is water. Both quite true, but very misleading.
This is because there is no readily available source of hydrogen in its pure form. Most hydrogen is either combined with carbon in hydrocarbons such as oil and gas, or is combined with oxygen as water. That means that a significant amount of conventional energy is required to generate hydrogen which is useful. If generated directly from hydrocarbons, the hydrocarbons are consumed, requiring a large source of conventional petroleum and leaving the carbon to enter the atmosphere, primarily as the potent greenhouse gas, carbon dioxide. If the hydrogen is generated from water, electricity is generally used in a process called electrolysis. And, you guessed it, the process requires considerable energy, largely supplied by hydrocarbons today.
All of this means that hydrogen really should be thought of as energy storage similar to a rechargeable battery, rather than an energy source. With any technology generally on the horizon today, generation of hydrogen is both polluting and conventional energy intensive.
So, what are the alternatives closest to being viable? I'll exclude coal, nuclear and heavy oils, even though there is considerable potential for increasing production of these fuels with oil prices above $50/bbl. I consider them to be proven, conventional sources. Beyond that, the most viable way of reducing conventional energy use is conservation. We're talking compact flourescent bulbs, insulation and weather stripping, lighter vehicles, computer control of processes ranging from air conditioning to refineries. Conventional energy use could be significantly reduced with highly attractive investments in these technologies, assuming prices above $50/bbl. And more good news... these technologies can and should be invested in by individuals at the lowest income levels and will decrease the release of greenhouses gases in the process. You and I can make a difference.
Ok, so you wanted to know about the most promising alternative energy sources? Wind, solar heat and low grade geothermal. Let me take them one at a time.
Wind. There is enough energy blowing in the wind to satisfy all the world's demands several times over. We just have to capture it. Unfortunately, that is not necessarily so simple. Most of the wind energy is in remote locations and/or at high elevations. That means a robust electricity transportation system is required. Wind energy is also highly variable. That means either batteries or interconnection of widely varied regions to even out the supply. There is a lot of investment in battery technology today, but for the foreseeable future energy storage in batteries looks like a marginal investment unless grid power is not available. All that said, I think wind energy is currently the most viable alternative energy source.
Solar heat. Notice I'm not talking about generation of electricity by photovoltaic cells, the technology most touted today. In general, photovoltaic cells are not viable alternatives to grid electricity at anything approaching today's energy prices despite the fact that many times world demand is available for the capture cost. This is true because of the high cost and low efficiency of today's cells, as well as because of the variability issue discussed in the section on wind. Solar heat, however, is one of the best, but least recognized alternative energy sources, particularly where electricity is utilized for these purposes. A large part of our energy consumption is for heat and cooling, both of which can be supplied through solar heat. The variability issue can largely be overcome by energy storage in mass such as water, earth and concrete. And, in the case of air conditioning, the largest loads correspond to high solar energy supply periods, ie sunny days.
Low grade geothermal. Again, I'm not talking about the few locations where high grade geothermal is easily accessible to generate steam. These areas are too sparse and protected to generate significant energy supplies. But just a few feet in the ground is an energy supply at nearly constant temperatures which can be tapped for heating and cooling. This applies nearly everywhere there are major populations. A heat pump can extract either heat or cooling (or both at the same time) from this source at substantially higher efficiencies than from the more variable ambient air temperatures.
So there you have it. I realize I've been rather cryptic in my explanations, but perhaps I can go further into the details in the future. So, keep those questions and comments coming.