$ Solar Technologies Review

In the past century, scientists had foreseen that fossil oil fuel would be serious shortage on earth some day in the future. Fossil oil was under $ 30 USD / barrel before year 2000. Fuel and gasoline prices were under $ 1.60 / gallon. Few people took a serious consideration using solar energy.

As the time going on, just after pasted half of a decade, the oil and fuel prices has climbed up a to an incredible level. The oil price just bumps up to $ 75 / barrel, at the time when this article was under writing on April 22, 2006. The regular gasoline price was $ 3.35/ gal. They broke the price record of the history. People now are getting fear. If the oil price stay at this level for long time, it would lead to inflation and economics recession soon. Who knows what price the oil and fuel will be by the end of this decade 2010 ?

Today, the most promised energy source is the Sun, the most abundant resource is water. Sun ray energy is vast, infinitive, enough to create multiple incredible powerful destructive hurricanes each year, to sweep over continents. That is the nature of the earth to auto adjusting the surface temperature of the continents.

How can we harvest the Sun light, natural water and sea water ? How can we transform Sun ray and water to motor vehicle s’ fuel by utilizing a solar energy transforming system ? How can we make massive production of fuel that is inexhaustible clean, renewable and “0” zero pollution to our living environment? What solar power technologies can we take reference ? Is it possible to build a solar powered fuel generation system that is most cost effective, high efficiency, affordable to household, able to use at your house backyard. If such an solar system is invented, ‘The Energy Revolution’, ‘The Industry Revolution’ will happen !

Today, all available technologies of collecting and inverting solar energy meet either 1 of 3 barriers, 1. Low efficiency ; 2. Too high investment cost $ / per Kilo-Watts; 3. Too large scale for households use.

These are some of reasons why we still rely on fossil oil and gasoline for our daily motor vehicles fuel.

However, we still have some successful technologies approaching : 1. Fuel cells technology; 2. Fuel cell vehicle. By a few years after, most of new motor vehicles will become fuel cell vehicles. Hydrogen gas will be one of main stream fuel for motor vehicles. Hydrogen fueling stations will be available nationwide soon.

The question is ‘How soon ?’

The answer is: If an efficient and practical solar hydrogen fuel direct producing system is invented earlier, the replacement from gasoline fuel to hydrogen fuel will become sooner. The age of using fuel cells, and fuel cell vehicles will get started from there.

Fuel Cell principle à

Despite Sun ray is infinity, but is low density energy around us. To harvest the Sun ray energy, we need to collect large area of Sunlight, and to accumulate the large solar energy, high enough to power generator or to invert 110V AC electricity for household use. We will give a brief analysis to each of common seen Solar-To-Electric technologies at follow, so that to see the challenges of the 3 barriers.

Can do solar-to-electric direct conversion; they take smallest surface space, simple structure, easy scalable and easy to install, good for any household and family use. That is reason why solar cell panel is the most popular among all types solar systems. However, Solar cells are extremely low efficiency, and high cost. The conversion efficiency ratio of solar-to-electric is about 8-12%, because the solar cell silicon chips can capture a very small portion of Sunray photon. 90 % photons of sun ray go through the solar cell chips, and remain at heat on the chip base. Roof mount solar panels

Multi-crystal solar cell

100W Solar cell panel cost at $ 700

In the market, a piece of 100 Watt power (maximum 6 A x 16.5 V ) multiple crystal high class solar cell panel costs about $ 700 USD. The investment cost to power ratio is $ 7000 / per Kilo Watt, NOT include the cost of a Sun tracking automotive driving system and inverter. A piece of 18 Watt power (1.2A x 15V ) single crystal type of solar cell costs $ 150. Its cost to power ratio is about $ 8327 USD / per KW. Its efficiency is only 8%. The highest conversion ratio of multi crystal solar cells array are about 20%, but the price cost is more than double. Those are good for aerospace, aviation, instruments, special mission applications etc.

Solar wind turbines are good for long season specific windy area, like ocean coast, water front, high hill. It can run day and night. Solar wind turbines normally are set up as multi clusters maintain the power. Each location set up need specific survey. They need wind direction tracking system to enhance efficiency. Wind turbines are large construction systems, high construction cost to set up and erect, and can only be erect at countryside area. It’s suitable for remote village grid power engineering. Solar wind turbine is less power sustainability. Sometime, a sunny day good for other type of solar systems, but it dose not mean a windy day or strong breeze day to power the wind turbines. Solar wind turbines are not suitable for city households use.

Solar parabolic dish collector( or reflector ) can concentrate sun ray to its focus point up to 100 times of its normal intensity. Working under direct-beam sunlight, the focal point temperature can reach 600 ^o C to 1200 ^o C degree, depend on the diameter of the dish.

The Sandia National Laboratories had developed a type of giant solar dish that can produce 25 KW of daytime power. And its solar-to-electric efficiency was announced 30 %, the highest in the world. The prototype cost is about $ 150,000. The calculation cost to power ratio is about $ 6000 / per KW

The initial cost is so high that is not good for households use. The reasons of high cost are because : high cost to manufacture large structure accurate focus parabolic, especially to large size over 20 feet diameter dish; high framing cost and high assemble cost; high cost to build accurate 3 dimensional tilt-able sun-ray auto tracking and focal pointing system that must be within 1 degree angle accuracy; high cost to make heat-to-mechanical-to-electric conversion engine( call Stirling engine) that must withstand over 1000 ^o C temperature at focal point. Such high temperature can melt metals.

High cost stirling engine having Hydrogen or He Helium inert gas inside

All these disadvantages have narrowed the solar dish application, despite its high conversion ratio: The conclusions are : Not for household use; Not a cost effective system; Not good for mass production.

It’s also called solar chimney. There are 2 types of solar power towers. ( See the next photos ) : A. Heliostats reflective power tower; B. Heat absorbing vent turbine power tower. Both of solar tower systems are giant and high construction cost, low efficiency, only good for remote village grid connection power supply at countryside. They are not for households use.

Can concentrate solar ray about 40 times intensity, depend on the trough size. Focal line temperature is about 350 to 400°C. The following images show the solar parabolic trough operation principle.

Solar trough has multiple distinctive features and advantages over other types of solar systems:

In fact, grid application giant solar trough farm systems have been massively installed in California Mojave and Kramer Junction. à

The next illustration shows how the solar trough farm system work. Sun ray charges oil fluid flowing in the parabolic trough focal pipes up to approx 350 to 400°C. high temperature oil is transported to both steam boiler and thermal energy storage system. High temperature oil charges the water flowing through in steam boiler to high pressure steam up to 10 to 15 bar. The high pressure steam pushes steam turbine and power generator to produce electricity.

Partial of solar ray energy heats salt fluid to high temperature and hot salt is stored at the thermal energy storage system. When it ‘s dark, the solar trough field oil circuit is shut off. Hot fluid salt release heat energy back to oil. The oil transform heat to steam boiler. Thus steam turbine can continue to work at night.

In the past 3 years, family monthly utility bill expense was increased less than 25%, However, fossil oil and motor vehicle gasoline prices have bump up more than double.

Now the priority to us is to invent a solar powered Hydrogen fuel generator and fueling system that can produce inexhaustible H₂ gas to best work with new generation fuel cell vehicles. Furthermore, we should consider designing house backyard size solar H2 fuel generator for house hold self sufficient H₂ fuel supply, prior to large solar farm fuel production system. If this dream came true, families would not need to go gas fuel station at all except long distance trip driving.

Review all solar systems and technologies we have described above, we found non of them can do the priority job that we dream for. All existing solar energy systems are solar –to– Electricity type. Too expensive to build, and too large for households use except the solar cell.