Solar Events

Facts about Solar Energy

Solar energy (or at least, the direct utilisation of the energy from the sun’s rays) is no longer a cinderella science, now that climate change, global warning, and the depletion of fossil fuels have become such hot topics. But in fact all our past older power sources were themselves indirectly using power received from the sun in previous time periods, so in a sense these technologies use solar power too.
Nonetheless, things are changing, and in a report by Shell Renewables, a division of one of the world’s largest oil companies – it is projected that by the year 2050, one half of the energy used worldwide will come from direct solar and other renewable sources.
Back in 1952, a report prepared by the Paley Commission for U.S. president Harry Truman predicted a bright future for solar energy. Among other things, the Paley report estimated that 13 million solar homes would have been built by the early 1970’s – just when the world was hit by the first energy crisis of modern times. But the prospects outlined in the report quickly dimmed. Many people think this was due partly to the Atoms for Peace initiative, announced in 1953, which led countries all over the world to start programmes for peaceful uses of atomic energy.
In the past few years, however, modern solar technologies have been penetrating the market at faster and faster rates, and an optimistic view of the sector’s future seems fully justified.
Nonetheless, past experience should make us aware of the fact that the most optimistic view of the future of solar energy could be set at naught by the appearance of an important invention or by unforeseeable events. Predicting the future is especially hard when the world is changing as quickly as it is in our day.
Can technological developments and the transition to a culture that is more aware of the need to safeguard the environment help create a world powered by the sun’s energy?

A technologically advanced world

The fast pace of technological development is one of the most significant characteristics of our time. Today it takes only a few months to achieve the same number of important inventions and discoveries that took decades, if not centuries, in the past. This trend is accelerated by globalisation, which in turn is accelerated by the ever-growing use of the Internet. Technological development helps raise standards of living around the world. Diseases that afflicted humanity for centuries have been nearly eradicated, and life expectancy has lengthened in most countries. But many problems have not been solved yet, and others are in the offing.
The two common factors that underlie many of the problems threatening our future are the fast growing population and the ever increasing consumption of resources driven by the diffusion of life-styles that have developed in industrialised societies and are emulated in much of the world.
Until the discovery of fossil fuels and the beginning of the industrial revolution, the sun’s energy – in its different forms, direct and indirect (such as wind and biomass) – was the sole energy source that inspired and enabled the development of human societies.
Since then, and especially in the past one hundred years - a relatively short span of time - a powerful energy infrastructure that now covers practically the entire planet and is based on fossil fuels and nuclear energy has been built. Today the world consumes 9 billion toe per year, compared with around 500 million toe in 1860. These facts about solar energy are becoming more widely relevant. While these energy uses and infrastructure do not yet benefit billions of poor people who still try to make do with firewood, they give humanity a power over nature that earlier generations never knew; they had to survive with the renewable energy of the sun.
This power helps us live more comfortably than past generations, but while it meets new needs, it also carries the risk of irreversibly altering natural balances, both local and global.
The world’s population has been growing rapidly over the last century and continues to grow. We were 1.6 billion in 1900; we have now passed the 6 billion mark. If this trend continues, the human population will rise to about 9 billion by 2050. The increasingly crowded world has also become a world of cities. Fifty percent of the population already live in cities and the figure is expected to rise to 75% by the year 2050. Dozens of cities already number more than 10 million people.
Dramatic contrast between wealth and poverty has become part of any urban landscape, with excessive consumption among the richer segments and the inability of the poorer segments, especially in the developing countries, to meet their most basic needs: decent homes, clean water, health care, education. If these legitimate and ever-growing needs are to be met, energy consumption must increase. What part can solar energy play in this process?

Solar energy, history and future

With the exception of nuclear, geothermal and tidal energy, all forms of energy used on earth originate from the sun’s energy.
Some are renewable, some are not. Renewable is the term used for forms of energy that can be regenerated, or renewed, in a relatively short amount of time. The regeneration process may be continuous and immediate, as in the case of direct solar radiation, or it may take some hours, months or years. This is the case of wind energy (generated by the uneven heating of air masses), hydro energy (related to the sun-powered cycle of water evaporation and rain), biomass energy (stored in plants through photosynthesis), and the energy contained in marine currents.
The energy contained in fossil fuels, coal, oil and natural gas, likewise comes from the sun’s energy, but it was stored in plants millions of years ago, and once used, it cannot be regenerated on a human time scale. The earth’s remaining fossil fuel reserves can probably provide us with energy for another 100 to 500 years, but this is an insignificant amount of time in terms of the whole past history of human civilisation and (one hopes) of its future.
The flow of renewable solar energies on earth is essentially equal to the flow of energy due to solar radiation. Every year, the sun irradiates the earth’s land masses with the equivalent of 19 trillion toe. A fraction of this energy could satisfy the world’s energy requirements, around 9 billion toe per year.
For thousands of years, the sun’s renewable energy was humanity’s sole source of energy. Its role started to decrease only a few centuries ago, with the progress of industrialisation, the diffusion of new technologies, and the discovery of new fossil fuels (coal has been used since ancient times) and eventually nuclear power.
Today solar sources provide around 10% of the energy used worldwide, but in the developing countries their share is still of the order of 40%. This contribution could start growing again, thanks to progress in solar technology and the pressure of recurrent energy and environmental crises related to fossil fuels and nuclear power.
To raise the contribution to 50% of world energy use by 2050, as suggested in the Shell Renewables report, would require sweeping changes in our energy infrastructure. These changes can be achieved only through the parallel development of a new, more sophisticated way of thinking about our environment and how we generate and use energy: a new culture that should pervade every part of society and shape the responsibilities of each.

Current solar technologies

Solar technologies – some primitive, some more advanced – have been used in all ages and in every corner of the world, but the invention and development of modern solar technologies goes back only forty or fifty years. By now the world has seen numerous practical demonstrations that sophisticated solar-powered facilities can be built and operated successfully as part of energy systems ranging from the scale of an individual home, to a large industrial or commercial complex, or even a whole city or rural area.
As early as the 1980’s, a 354-MW solar power plant was built in the Mojave desert, in California. Here the heat contained in solar rays, concentrated by reflecting troughs and raised to 400oC, produces steam that runs a conventional power generator. When the sun is not shining, the plant switches to natural gas. The latest generation of this type of plant incorporates new engineering solutions and new scientific principles such as non-imaging optics, which makes it possible to build much more efficient concentrators at lower costs. These developments open new prospects for the technology in the sunniest parts of the world.
A solar technology that has already had a great impact on our lives is photovoltaics. Not in terms of the amount of electricity it produces, but because of the fact that photovoltaic cells – working silently, not polluting – can generate electricity wherever the sun shines, even in places where no other form of electricity can be obtained.
The technology has been around since the 1950’s, but the effect on our lives is not widely known. As the American solar-technology historian John Perlin observes, it was the determining factor in a whole series of otherwise unthinkable developments.
For instance, photovoltaic cells generate the power that runs space satellites. Without telecommunications satellites, many of our now-routine activities – from watching internationally broadcast entertainment to using cell phones – would still be in the realm of science fiction. And space exploration and research too might still be science fiction.
On earth, photovoltaic technology is used to produce electricity in areas where power lines do not reach. In the developing countries, it is significantly improving living conditions in rural areas. Thanks to its flexibility, it can be incorporated in packages of energy services and thus offer unique opportunities to improve rural health care, education, communication, agriculture, lighting and water supply.
In the industrialised countries, programmes that provide incentives for the incorporation of photovoltaic systems in building roofs and walls have tallied up thousands of completed projects in the United States, Japan and Europe.
Annual worldwide sales of photovoltaic systems are growing by around 30% and now stand at about one billion dollars.

The use of energy in the form of heat is one of the largest items in the energy budget. In Europe, for instance, it accounts for around 50% of total energy consumption: around 630 million toe, of which 383 in low-temperature heat and 247 in medium- and high-temperature heat.
Today, low-temperature (<100oC) thermal solar technologies are reliable and mature for the market. Worldwide, they help to meet heating needs with the installation of several million square metres of solar collectors per year.
These technologies can play a very important role in advanced energy-saving projects, especially in new buildings and structures that require large amounts of hot water, heating and cooling.
Seeing buildings as complex energy systems and as the largest collectors of solar energy
Buildings are the modern world's main and most widespread technological systems, and the most direct expression of a people's culture of life and work. Most of the energy we use – around 40% of primary energy in Europe – goes into heating, cooling and lighting building interiors and into running a growing number of devices used in buildings. Designing, building and managing energy-efficient buildings with low environmental impact is an ongoing challenge.
Over the past few decades, building roofs and walls have been continually transformed by the incorporation of new energy-related elements such as insulating materials to high-performance windows, special glass, solar-powered heating and electricity-generation systems, and low-consumption light bulbs.
Architects are switching to the "whole building" approach, which sees the various problems and solutions as a whole and tackles them in an integrated and intelligent way right from the start of the design process, when every choice is decisive.
The challenge is to move beyond the simple concept of "energy saving" or "solar energy" and aim at a combination of these and optimal building management. The basic idea is to create better buildings by putting together a strongly interdisciplinary team capable of analysing and evaluating the different aspects involved in the building's life cycle, and striking a good balance among the proposed solutions. The factors involved include the building's site and position, and the use of active and passive solar systems.
The project must take account of waste management, maintenance, the choice and reuse of materials and products, optimisation of the technological installations, the financial aspects, the landscape and the environment, combining them all in an integrated whole.
The design process should dictate the choice of technologies, not the other way around, as often happens today, when available technologies and products guide the design process.
In recent years, the International Energy Agency's programmes on "Advanced Low-Energy Solar Buildings" have sponsored a number of products aimed primarily at energy saving and energy efficiency, but also at the introduction of solar technologies to meet the remainder of a building's energy requirements. These experiences have proved that it is possible to construct buildings that use on average only 44 kWh/m² per year, compared with 172 kWh/m² in other contemporary buildings. The lowest consumption obtained so far, 15 kWh/m², was in a home built in Berlin.
According to new building codes proposed in some northern European countries for future buildings, the amount of energy needed for winter heating can be reduced to practically zero with technologies that are already available (insulation, special glass, heat recovery, passive solar design and energy storage), and the remainder can be covered with active solar devices incorporated in the building's skin – devices that are not necessarily invisible, but are aesthetically designed for these buildings of the future.

Technological progress and cultural challenges

The invention and development of modern solar technologies began forty or fifty years ago. Tremendous progress has been made, especially in the last decade, and these things need to be taken into account as part of the established facts. About solar energy and its future there can no longer be any doubt. A great number of solar, wind and biomass technologies for the production of fuel, heat and electricity are now available or close to commercialisation. They have been installed on a significant scale in both developed and developing countries. They are used in many different ways, stand-alone or incorporated in conventional energy networks and grids. They are already providing energy services to individual homes, villages and cities.
However, if we are to move from examples to worldwide applications of solar technologies in communities, cities, islands and rural areas, society as a whole must be interested and give its support. Solar energy infrastructure, whether installed in remote rural areas in a developing country or integrated in existing conventional infrastructure in a city in the developed world, needs to be better known and accepted.
If we want the use of solar energy to spread through the technologically advanced world to the extent mentioned above – 50% of world energy consumption by 2050 – we will need to enroll many more solar scientists and engineers, environmental scientists, entrepreneurs, financial experts, publicists and architects. Above all, we will need many more politicians and civil servants who know the subject and are more courageous and determined. A new generation of solar-energy pioneers has to be nurtured, especially to work in local communities and industries.
Solar energy exists everywhere, but has a weaker concentration of energy than fossil and nuclear sources. Using solar energy can teach us how to establish a more balanced relationship with nature. A new culture of energy efficiency can lead to a more concerned, socially responsible use of all natural resources. The use of solar energy – a local resource – can contribute to the preservation of local cultures and also promote new lifestyles and new concepts of wealth, prosperity and security that can help us all meet the challenges of the 21st century.

The facts about solar energy reveal to us more clearly every day that it has a bright future as a powerful contributor to the energy needs of the 21st century.

6 Comments so far

  1. Krisztina October 27th, 2006 9:39 pm

    These are some useful websites on solar technology:

    ( for solar oven history info) ( excerpts from the book, Heaven’s Flame, by Joe Radabaugh.)

    ( for solar oven history info)

    ( for solar technology info)

    ( for solar technology info)

  2. Krisztina October 27th, 2006 9:41 pm


  3. Krisztina October 27th, 2006 9:47 pm

    Alternatives to fossil fuels are being considered, and the US is highly considering switching almost totally to alternatives to fossil fuel, esp. Ethanol in a few decades.
    Arizona is considering using more wind energy soon as well.

  4. mar-kate June 6th, 2007 10:06 am

    how many people use solar power world-wide today

  5. UPALI M SEDERE October 30th, 2007 4:02 pm

    Ultimate answer to the energy crisis is solar power. Nothing much is done in schools, except in few places, to educate and prepare the next generation to vigorously address the issue of developing new technologies to tap solar power. This should be promoted.

  6. katie March 16th, 2009 10:47 pm

    hey we have to do a project on solar energy @ school and this a really help!

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