In the future sustainable world, it is probable that per capita fossil fuel consumption will have to be very nearly zero. The use of fossil fuel resources will be restricted by cost and availability to only the most critical and high value applications. Total population, and how well we control and reduce it worldwide, will be the biggest factor in how hard the changes are, getting there, but technological advances must be significant as well. While the total use will eventually decline to a few drops of petroleum per day (or week, or month), the goal will need to be zero, and from the standpoint of long term planning we need to start pursuing that goal now. Even with the most restrictive conservation measures, we will still need a lot of energy per person. If, as I’ve read, the average person in North America today uses 16 times the world average of energy per person, and more and more people in the developing world are striving to at least approach the way we live in NA, we have a huge challenge to overcome. (More arithmetic later …) How will we live, and where will our energy come from in a world no longer using petroleum and coal for power?
I had this thought when I was doing the spring raking of my lawn. I was thatching out wheelbarrows full of dead grass and leaves, and it suddenly occurred to me that, in the future, instead of dumping my yard waste into a compost pile, I might be dumping it into an oil drum converted into part of an energy conversion system. I envision this system using at least two stages.
One small tank behind the house will concentrate sugars into a liquid that can be fed to a biological fuel cell that produces either electricity or a more refined fuel (or both). A second tank may handle the materials containing less sugars, including the waste from the first tank, in a more concentrated bio-reactor that produces heat and possibly more electricity. Any waste heat from either tank would be recovered and used to produce electricity or directly heat the house.
Of course, my yard rakings wouldn’t probably produce a lot of energy, but I would have a garden alongside the house (maybe the front yard) that would increase the amount of material available somewhat, and most waste produced in the house would feed the system. In fact, products and product packaging would be designed to feed such systems.
Beyond that, I fully expect to have the roof covered in solar cells and thermal conversion devices, making sure that as broad a range as possible of wavelengths in received light are converted to electricity, and that any waste heat is converted to electricity or used to heat water. Perhaps the outside walls of the house, and even the driveway surface, would essentially be solar cells. Small turbine generators in the downspouts could generate electricity from any precipitation flowing down them, until it hits the filter systems and cisterns where it would augment the fresh water supply for the house. Everything will be engineered to need no disposable components, and trash and recycled materials collection will handle end stage materials, perhaps a sludge some kind, that is just the matter than either has toxic components or from which all potential energy has been extracted.
It is possible that building insulation will be enhanced with heat-to-electricity conversion capability, and eventually that may become as important a function as providing insulation. Perhaps everyone will have small, highly efficient wind turbines on their homes and in their yards, and every power pole will have a device on it that collects power from the wind, maintained and operated by the utility company.
Personal vehicles could have electricity-generating solar paint to augment their fuel cell power sources, which might also be able to draw power from yard waste-derived fuel. Simple, highly efficient mechanical designs would simplify our vehicles, and power steering and brakes would be long gone, replaced by elegantly designed mechanical systems. Almost every bit of energy in the vehicle would be converted to motion or electricity, and even waste heat in the gears might be recovered and re-used.
In some areas geothermal energy can be tapped to provide a large scale energy source, but it has not been developed yet to handle anything like the capacity that will be needed. Wave energy has potential along the coasts, but has its limitations. Solar energy is available almost everywhere, though it is less cost effective in perennially-cloudy or very high latitude areas. Wind energy is available in some areas, but conversion efficiency combined with maintenance costs still limit it’s development. In all of these areas major, basic research needs to be applied to provide significant increases in efficiency, decreases in cost, and the capacity to produce and install large quantities of the technology quickly.
Now for a little arithmetic. If we in North America are each responsible for 16 times the world average of energy consumption, we also need to consider that the energy used worldwide is probably at least 95% derived from fossil fuels. To use just our share of energy when there is no longer fossil fuel involved, we need to use 5%, or one twentieth, of the world per capita average of energy use, and 1/16*1/20 = 1/320th. That will be offset to the good by increased alternative energy sources, but offset to the bad by population increase. If we can increase alternative energy production to provide one quarter of our total energy supply, and reduce our per person consumption by half, we are still using (1/4*1/8=) 32 times as much energy as the world average with fossil fuels out of the picture. Obviously, population and the industrialization of the third world present huge issues that must be controlled and mitigated.
In the future we will need to save and maximize the efficiency of every watt of power, every degree of temperature difference, and practically all of our power will have to come from sources we are only beginning to develop now. This will be a huge change, and will require a “full court press” on the fronts of education, basic and applications research, the rapid commercialization of new technologies, and the hard work of converting or replacing the old energy infrastructure and changing our very ways of life.
We all have much to learn and do. As always, I welcome your comments.