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Energy Compensation Using Solar Power Stations in Space

1. INTRODUCTION: FUTURE ENERGY NEEDS

Mankind has recently enhanced its living standard and its population in an explosive way. In fact, the human population quadrupled and primary power consumption increased 16-fold during the 20th century [1]. The consumption of energy, food, and material resources is predicted to increase 2.5 fold in the coming 50 years. As a result of our efforts for better life, we have come to face, in this 21st century, serious global issues threatening our safe life or even our existence itself on our mother planet earth. These are issues such as global warming, environmental degradation, declining nutrition on land and sea from rising CO2, and rapid decrease of fossil reservoir. Since the living standard and the population of developing countries are increasing continuously, the demand of energy will be several times larger than that of today’s requirement by the time of the half way of this century.

In 2000, the world had 6.1 billion human inhabitants. This number could rise to more

than 9 billions in the next 50 years as shown in Fig.-1. This future population increase is mostly due to very rapid increase in less developed countries although the number in more developed countries will be almost constant (about 1 billion) or rather decrease [2].

Fig.-1 World Population Prospects [2]

The explosive increase in the human population inevitably requires an exponential increase in the consumption of energy, food, and material resources. One primary power source at present comes from fossil fuels such as oil, coal and natural gas. However, the fossil fuels have two serious factors which prevent them from being used for a long term as primary power source. One is their limited amount that does not last long if used with the same or higher pace than that of today (Fig.-2). The other is their negative feature of emitting carbon dioxide, one of the green house gases, which causes the global warming.

Fig.- 2 Pattern of Global Energy Dependence [3]

Fig.-3 Atmospheric carbon dioxide monthly mean mixing ratios. Data prior to May 1974 are from the Scripps Institution of Oceanography (SIO, blue), date since May 1974 are from the National Oceanic and Atmospheric Administration (NOAA, red). A long term trend curve is fitted to the monthly mean values [4]

Atmospheric CO2 has increased from 275 parts per million (ppm) before the industrial era begun to 379 ppm in March 2004 as shown in Fig.-3. Some scientists suggest that it will pass 550 ppm this century. Climate models and paleoclimate data indicate that 550 ppm, if sustained, could eventually produce global warming comparable in magnitude but opposite in sign to the global cooling of the last Ice Age [5].

Global energy demand continues to grow along with worldwide concerns over fossil fuel pollution, the safety of nuclear power and waste, and the impact of carbon-burning fuels on global warming. As a result sustainable energy sources like solar, wind, hydropower, biomass, geothermal, hydrogen, ocean thermal, tidal power etc are drawing prime attention, out of which solar power is the most promising one. Terrestrial solar power has too many limitations like atmospheric attenuation, daily and seasonal variation, and affects by climate conditions etc. To overcome these limitations concept of Solar Power from Space is getting momentum, which was first proposed by Czech-American engineer Peter Glaser as a solution to the oil crises of the 1970s [6]. Solar Power from Space is a proposed concept to place a gigantic solar power station in space orbiting around the earth that uses microwave power transmission to beam solar power to a very large antenna on earth where it can be used in place of conventional power sources.

2. SPACE SOLAR POWER (SSP) vs TERRESTRIAL SOLAR POWER (TSP)???????????????????

The SSP concept arose because space has several major advantages over earth for the collection of solar power. Space is free from day-night cycle, atmosphere, clouds, dust, rain, fog and other climatic changes, so it would receive 30% more intense and at least eight times more sunlight than that of at ground constantly and continuously unaffected by the weather. In geosynchronous orbit it would receive sunlight almost 24 hours a day hence avoiding the expensive storage facilities necessary for earth-based solar power systems.? Since earth?s axis is tilted, it would be in earth?s shadow only for 70 minutes maximum at late night when power demands are at their lowest, during 42 days near the equinoxes [7] as shown in Fig.-5.

Fig.-5 Daily duration of eclipses as a function of the date [7]

3. SSP: SYSTEM DESIGN AND TECHNOLOGIES

The SSP system is composed of a space segment and a ground power receiving site (Fig.-6). Space segment consists of mainly three parts; solar energy collector to convert the solar energy into DC (Direct Current) electricity, DC-to-microwave converter, and large antenna array to beam down the microwave power to the ground. Ground power receiving site uses a device called rectenna (rectifying antenna) to receive and rectify the microwave power beam. The rectenna system converts the microwave power back to DC power which is then converted to conventional AC (Alternating Current), and is connected to existing electric power networks.

Assuming typical values for efficiencies like 15% for solar panels to convert solar energy into DC, 70% conversion rate in the space segment from DC to microwave, 90% beam (power) collection efficiency, and 80% conversion rate for rectenna from microwave to DC in ground segment, the estimated over-all efficiency is approximately 7.5 %. With such efficiency a SSP space segment would be of size of about 50 km2 (5 km x 10 km) to generate 5 GW DC power on earth (Fig.-6).

Fig.-6 : Reference Model: 5 GW GEO based Space Solar Power Station Designed by US Department of Energy (DOE) and NASA in 1979 [8]

3.1 -SOLAR CELL: EFFICIENT STRUCTURES

In the very near future, breakthroughs in nanotechnologies promise significant increase in solar cell efficiencies from current 15% values to over 50% levels. That might decrease required size of space segment by about 3 fold. Author proposes Metal-Metal junction cavity solar cell which theoretically promises to increase solar-electric conversion efficiency many folds.

A cavity of metal m2 (work function W2) with thin polish of metal m1 (work function W1, W1 <W2 , Fig.-7) on inner surface, with a pin hole is kept at the focus of the solar concentrator coinciding the pinhole and focus. Pinhole is covered with transparent glass to protect inner polish of cavity from atmospheric reaction. Such cavity behaves as metal-metal junction solar cell (termed as M-M cavity solar cell) with various features (described below) leading to enhancement of solar-electric conversion efficiency.

?? The major loss in usual structures is the reflection loss (about 30%) but in M-M cavity solar cell once ray enters in cavity, undergoes multiple inner reflecti

Are Alternative Fuels on the Road to a Solution?

There are many innovative solutions to the current questions concerning high gasoline prices and greenhouse emissions. Crops grown especially for fuel. Ethanol made from corn has no harmful emissions it is made from a reusable resource, the US government is pushing for 80% bio-fuel mixed with 20% gasoline, they can better than that! Bio-fuels produced from crops such as soybean and corn are at an effective alternative to gasoline both being a renewable resource that helps the farmers have a constant demand for their crops all the better for a continuous cash flow. However, if all the corn currently grown in the US was used to produce ethanol it would only meet only around 12% of the current demand for fuel, more and more land is being bought up for the production of ethanol, and it’s largely dependent upon the weather, a yield of around 18 gallons of oil from corn can be produced per year per acre, more can be possible with genetic alterations, the growing process also requires fertilizes, pesticides and heavy machinery to harvest, effectively adding to soil contamination. It is also estimated the process uses as much energy to produce and transport as regular oil. There are also concerns that the farmland required for producing ethanol from crops will take up valuable space previously used for food crops, as recently food crops have suffered from extreme weather conditions and natural disasters pushing food prices higher, is then using this land, to produce ethanol feasible or even ethical?

Other alternatives being looked at are probably more efficient but less appealing to some, include reusing vegetable oil, a converter with filter, which can be placed in any diesel engine to allow it to take 100% used vegetable oil such as that from restaurants, it is refined slightly after being collected, and then sold at less than half the price of regular gasoline, higher end cars such as Saab and Mercedes are using this technology.

Water powered cars are also a reality by splitting the hydrogen oxygen (H2O) combo, that comprises water, and using the energy that is produced when they are put back together, these cells can be effectively be installed into cars reliant on petroleum, tailpipe emissions? Water.

Bio-gas energy sources have come up with a process of using organic wastes solids or liquids, do you remember in the movie back to the future, when the professor came back from the future at the end of the movie he stuffed garbage into the fuel tank and converting it into a usable gas product. Well at biogas energy sources they take food waste with other degradable organic matter like grass clippings, and by placing them through in holding tanks, they decompose naturally, the gas is siphoned off and the methane is used for powering generators boilers etc, or it can be refined further to make fuel for transportation.

However, the most exciting development of bio-fuel is that of using algae it is a fast growing high-yield product, 50% of it’s body weight is an energy source, it is quickly grown on ponds and requires no pesticides or fertilize to flourish, 20,000 gallons per acre per year can be produced on open surface ponds, Glen Kertz of Vertigro explains that different strains of algae can be used to meet other transportation needs for jet fuel and diesel if produced in contaminate free Vertigro, they grow the algae vertically in plastic bags hung in a green house, enabling more surface area to to exposed to sunlight and enabling an enormous amount of the water to be continually recycled, it also takes up far less space and therefore yield per acre is much more than 20,000 gallons per year.

With all these alternatives, when will it be feasible for these methods to be available the general public?

Fuel Made Of Straw And Wood

The race for a new fuel is on. Scientists around the world are testing products of every type in order to create a fuel of the future. What is the latest? How about a product called Bioliq?

Bioliq stems from biomass technology, which isn?t new in regards to taking masses of a substance and converting it to energy. But turning those masses into diesel fuel is something that is new. How does it work? To start, all one needs are the agricultural leftovers from farms or even the trees thinned from forests. Once gathered, the straw or wood is put through an intense heating process that changes the product into a new substance. This substance is then converted to fuel. Why is this important? For environmentalists, this means a fuel that doesn?t have to be extracted from a limited supply buried beneath the earth but is created from a renewable byproduct.

Still don?t understand how straw becomes fuel? This is how it works. First, the plant material, in the absence of air, is heated to around 500?C, a process known as pyrolysis. This produces a thick oily liquid containing solid particles of coke termed biosyncrude. The biosyncrude is then vaporized by exposing it to a stream of oxygen gas, before being heated at high pressures to a temperature of around 1400?C. known as gasification.? This process transforms the liquid biosyncrude into a mixture of carbon monoxide and hydrogen termed syngas.

After any impurities are removed from this syngas, it can be catalytically converted into a range of different chemicals and fuels, including methanol, hydrogen and a synthetic version of diesel.

Members of the Karlsruhe research center have estimated that their processing could bring the costs of producing liquid biofuels down around $2.65 per gallon.

Bioliq is now taking its first steps towards commercialization. In conjunction with the German process engineering company Lurgi, the construction of a pilot plant based on the bioliq technology should be fully completed in 2012. Once the plant has been built, large amounts of fuel can then be created. The question will then be how best to distribute this new fuel in large scale so that it can effectively compete with fossil fuels. As fossil fuels decrease in supply and increase in price, tax incentives have been discussed as the answer.

So what will be the new fuel of the future? It is hard to tell at this point, but many good ideas are being tried and tested, which means hopefully they will soon be available to the whole public for use.

Fuel To burn – Why Oil is going Up & Down

What exactly is deriving oil prices high. Is less shortage of oil, oil production issues or simply demand for oil has sky rocketed. What we see today is only tip of iceberg. The day is not far when we will see oil barrel at $200 or more. While emerging economies are battling with established economies for control of third world oil for growth of business. The nations have started capturing untapped oil market for future expansion, along with current rising consumption of oil is the leading cause of price touching record high. What exactly, we have options for Fuel To Burn beyond Oil.

According to statistic, the America consumed 20 million barrels of petroleum every day in year 2006. This is really a big number but when we look at the numbers of China and India and other emerging economies the situation looks more grim.

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There is urgency to come up with alternate fuel solution to oil, the world leaders, corporate leaders and environmentalist are working closely to create alternate fuels. The research universities are working tirelessly and corporate leaders are pumping huge amount for future fuel technologies.

We all know oil is made up of fossilized remains of ancient marine plants and animals, we also know this process takes millions of years to convert fossil into crude oil. The problem is there is a long process to get oil, where as demand for consumption is growing every minute in leaps and bounds.

Now the big question is, where do we stand if we run out oil. Already signs are not good. Refineries are running at high out put still not able to keep consumption requirements, Some of the oil rigs are running dry, sure signs of bad days. Some of the oil regions are involved in long conflict, resulting into delay and short supplies. Bottom line we no longer can depend upon on oil as major energy source.

Another factor, why alternate technologies for fuel are being pursued is the risk to environment. The most damage to earth has happened in last century, with explosion of industrial revolution and expansion of industries across all fields has created tremendous impact on global warming. People are able to see changes in environment, changing weather patterns, too much or no rain in different part of world, temperature soaring and glaciers shrinking all are signs of global warming.

The future needs are not only alternate fuel to gasoline but the future fuel has to be clean and no hazard to environment, unlike oil which creates greenhouse gases a prime reason of global warming. The next fuel will be clean, environment friendly, cheap and will be available in all countries. One more thing next generation fuel will help in reducing the tension among nations fighting for oil share.

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The emerging economies China, India and Mexico are buying or leasing oil fields in Asia, Africa and Europe to keep their counties interest intact. The developed countries are busy in filling their oil reserves to safe guard national reserves. All this fight for oil and fierce competition among nation is bound to create conflict and war. The next generation fuel not only will help in reducing consumption demand but also help in keeping peace in world.

Now we have talked in length about the current issues related in respect to gap in demand supply of oil. Let’s look at alternate fuels available and which one are in research. Read more on Green Energies????”http://www.fueltoburn.com/“

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