Heliostats-Sameshine vs Sunshine

A heliostat reflects light onto a target. The sun may be at its original strength (less losses on reflection) or it may be concentrated or dispersed. The amount of sun a heliostat is able to reflect to an ideal target over a day is greater than the amount of sun striking any fixed surface of the same area but not quite as great as the best tracking surface, for the heliostat turns only halfway into the sun.

Think about the thousands of ways the sun could be used if it did not move in the sky. We cannot prevent the sun going off and on, for the earth still spins and clouds come and go, but we can easily and eventually inexpensively have the sun stand still. Today no one craves the sun to stand still. If we suddenly could produce inexpensive, reliable heliostats, there would not likely be an immediate large demand for them. It will take time for people to discover that sunlight passing through space always in the same direction has a multitude of uses that turning sunlight cannot have. Such sunlight will indeed need a new name, samelight, and sameshine.

Lighting

A square foot beam of sunlight can replace 200 watts of electric lights but sunlight moves and is soon shining in the wrong place.

( I have calculated that a 4" square mirror will deliver the equivelant of about 250 watts of incandescent light. redrok )

Samelight can be distributed directly by beam or fiber optics. Samelight can be dispersed inexpensively; 20 square feet of samelight can light a 2000 square foot building. To light, samelight needs electricity as a partner for the predictable and unpredictable periods of unlight (when there is no direct beam radiation.)

In the Southwest, over a year, a thousand watts of samelight could replace 2000 kWh of electricity. This saves $200/year yet the capital costs of transforming sunlight into samelight should be no more than $500/kW ($2500 for a 5 m^2 heliostat--8'x8') and yearly costs should not exceed $40/kW of samelight, $50/5m^2 heliostat maintenance, and $150/5m^2 set aside for replacement.

Water Heating

Samelight can be directed at a protected target that never freezes. Samelight can be concentrated. Samelight, unlike sunlight can easily be converted to extremely high temperatures, heat storage can be accomplished in smaller volumes than has been traditional in solar energy systems. For instance, with samelight we can cycle a cubic foot of rocks through 500 F which gives an energy storage of:
500x200Btu/F = 10,000 Btu/ft^3 or 3 kWh/ft^3 vs 1/5 this with sunlight.

Note that samelight can take on several entirely different tasks--as providing light when light is needed (light stands first in line since we cannot store light as we can store heat) and if light is not needed, a heliostat can be directed to a different target where samelight is converted to heat, electricity, cold, or mechanical power.

Electricity

Samelight can be converted to electricity with concentrating Fresnel lenses using PV cells. These same cells can be cooled convectively with water or other liquid and the energy used as both electricity and light. No inconvenient outside, flexible coupling needed. Samelight can power Stirling engines to produce electricity. During unlight, gas or other fuel can kick in.

Refrigeration

This is the perfect task for samelight. Samelight can operate existing absorption refrigeration equipment. Samelight is most abundant during times when refrigeration equipment is most needed and extra samelight can produce ice to store cool during times of unlight.

A Commodity

The same heliostats can be used for all the above tasks. A heliostat can be moved from one building to another or one task to another. The heliostat, once many uses have become established is a commodity which will be manufactured, after a time, by several large and efficient manufacturers.

Ten heliostats might be used one decade to pump ground water and then during the next decade (after the well was pumped dry) the same heliostats could be used to refrigerate a motel.

Heliostats and samelight can be used extensively in space and on other planets as we colonize them. Indeed, samelight and the uses we discover for it here on earth may be the crucial boost to give us confidence to get off our asses and out into space. Some planets have no clouds and therefore abundant samelight. In space, samelight is as easy to have as sunlight.

Problems

The great problem I see with samelight is fire hazard. It will be tempting to make concentrating heliostats that throw a beam of concentrated, lethally hot sunlight, rather than reflecting one sun to fixed concentrating targets. Concentrating targets are inherently safe; no hot spot wanders about, but concentrating heliostats can easily wander and start fires. This hazard may be so great that even if a safe business is started using flat heliostats and concentrating targets the devices will soon be misused and the entire business brought into jeopardy and perhaps finally failure.

First Uses

Trivial uses may lead the way. The first heliostats may shine on north facing billboards.

Sameshine Engineering

Civil engineering is much simplified by having gravity always work in the same direction. How could we construct buildings and canals and bridges if gravity changed its direction during the day? Furniture toppling from one side of the room to another each day, objects sliding north and south with the seasons. Naval and aeronautical engineers must face the problems the civil engineer avoids, for boats and planes pitch and roll.

In solar engineering, no one has the luxury of the civil engineer. The sun never stands still; it moves all day and each day is different than the last. The solar engineer accepts these impossible circumstances because he knows nothing else. Once the widespread introduction of heliostats produces a new branch of engineering of sameshine and samelight, these new engineers will marvel at how their predecessors grappled with the constantly turning sun.

A race of sailors that never touched land would not even know to identify seasickness. Sameshine engineers will understand and forgive the previous problems of solar engineers--after all they had to deal with unceasing sun-sickness and did not even know it.

Examples of engineering sun-sickness

Some of the symptoms of engineering sun-sickness have been low temperatures, low efficiency, and high prices.