Indirect Solar Power Technologies

Indirect might more accurately be called common sense solar power technologies as most of these techniques are really very obvious and involve very low tech to make them a significant way to harness solar energy.

First, lets talks about how nature harnesses electrical energy. Obviously the energy from the heats our planet. Most of the heat is radiated back to space in the form of reflected light or infrared radiated energy. The temperature of the surface of our planet is primarily determined by the amount of energy that hits the surface of the planet in relation to the amount of heat that is radiated back to space. If the earth gets hotter, more energy is radiated back to space, so there is a sort of regulation that takes place. The set point for the regulating system is determined primarily by the filtering-reflecting aspects of our atmosphere relative to the insulating-absorption aspects of our atmosphere.

When we speak of "green house" effect we mean that the insulating nature of our atmosphere is trapping energy and not letting it escape back to space. Obviously we want some of that effect, but it may be that too much is bad as well. The compound in our atmosphere that most significantly traps heat is water vapor. A distant second are hydrocarbons like Carbon dioxide, Carbon monoxide (which fairly quickly converts to CO₂), Methane and so on. Is "Global Warming" real and is it a direct result of human activity? I don't think the answer to that is know. In the 1980's there was a real fear that disposable diapers were going to bury the country and a lot of folks felt there was a strong scientific basis for that conclusion as well. What is clear is that oil and coal are not renewable sources and that as a race, we are consuming more resources than we can replenish by far. I do not really think that "reducing a carbon footprint" is a good justification for solar power. I think responsible stewardship of resources is an excellent motivation for pursuing solar power.

Photosynthesis which takes place in all plant cells, uses CO₂ in the air, water from roots or the air, and sunlight (UV light mostly) to grow and produce energy. You might say plants are really a crystalizing of carbon dioxide in the air through a biological process. For thousands of years, mankind has used solar collectors in the form of plants, to heat there living space and cook their foods by virtue of the plant matter they burn. Only for the last few centuries has man been using fuels which were not plant matter. For a while we referred to coal and oil pumped from the ground as fossil fuels. The picture is now emerging that coal may indeed be primarily petrified plant material, crude oil was likely created on a cosmological scale and is not a plant or "solar" derived energy source.

So, mankind is attempting to get back to living on our means, so to speak, by utilizing the energy income from the sun instead of foolishly wasting non-renewable reserves. You might say we are like rich children that have learned to live a grand lifestyle on an inheritance that was built up over many generations. If we don't start living within our means, we may end up as hurting spoiled brats with no options very quickly.

But not all solar collection schemes need involve engines or PV cells. Here is a list of energy concepts that may hold just as much promise:

1. High lipid plants for producing esters like diesel fuel. - By using a process called, "transesterification" which is very similar to the process of making lie soap, any lipid (fat) can be converted to a diesel like liquid fuel. Many attempts are being made to produce grains, vegetables, and even seaweed that is very high in fats. If more energy can be produced than is required to make this fat, then this is a nice renewable source for liquid chemical fuels that derive their energy from the sun.

2. High sugar plants for producing alcohols. - Sugar is easily converted to alcohol or even methane by biological processes. Yeasts and other microbes consume the sugar and yield the alcohol. If the process happens in an anaerobic (limited oxygen) environment then methane gas is produced which is the primary component of "natural gas".

3. Solar building techniques that use uneven heating to produce drafts for wind energy. These are similar to green houses in that they trap solar heat. By allowing heat to escape in a controlled way, a wind current can be created within the building which can be used to generate electricity. The concept here is that the collector can be huge at little additional cost beyond the cost of a building. The power generated is inefficient on a per area basis but efficient on a per cost basis.

4. Conventional wind energy harvesting. This is old as the hills, but new turbine designs and even turbulent flow crystal generators may breath new life into this technology. These systems are great for harvesting winds. Unfortunately there are few places on the planet where winds blow in a consistent and predictable manner. This is a great plan for capturing energy and offsetting other forms of generation. Most wind is caused by uneven solar heating of the earth so wind power is a form of solar power also.

5. Tide energy harvesting. The tides of the ocean as well as temperature differentials in the ocean can be used to generate power.

6. Water cycle gravity engines. - No DAMs - The idea here is that the sun drives the water cycle. As gravity pulls water downward in elevation, the energy of that water at height can be captured. This is currently done with dams with large headwaters. But there really is no reason a large headwater is necessary. In places where there is consistent flow of water, hydro-electric power can be harvested without submerging to large amounts of land. In those places where water is captured for water purposes, electric power can be harvested as a low cost benefit. In fact, a simple turbine on the bottom of irrigation reservoirs can easily feed grid systems. Simple AC induction motors made to spin at slightly higher than the free running RPM of the line frequency are inherent grid feeding devices. If you have any sort of water retention capability on your property, you might consider adding a one or three phase motor to a turbine on the spillway of your reservoir. You can probably offset your entire electric bill with the power generated thusly.

This list is only a few of the things out there. But DIY folks might find some of this as rewarding or even more so than conventional solar projects.