WHAT'S BLOCKING SUN POWER? The sun showers the earth with more energy every hour than what civilization currently burns with fossil fuels every year. Given this tantalizing bounty many greens view the resource as cheap, clean, noiseless and limitless. Yet despite 50 years of solar innovation the industrial world currently runs on 17 terawatts of primary energy mostly provided by coal, gas and oil. Solar, a determined energy underdog, provides but one-tenth of one per cent of energy demand. (Only 80 terawatt hours of the world's 22,000 terawatt hours generated by the global electric grid every year come from solar modules.) Nevertheless many experts estimate that solar PV and thermal systems if planted on the world's deserts occupying an area the size of Venezuela -- could eventually create about 15 terawatts of energy within 50 years. In fact solar is the only renewable with the potential to challenge the dominance of hydrocarbons. But many analysts suspect these figures, based on theoretical exercises, are way too optimistic. A group of Spanish engineers, for example, calculates in an unpublished paper that no more than two to four terawatts of solar energy can ever be successfully harvested for human use due in part to many of following realities: Geography: The sun does not shine brightly or intensely everywhere. As a consequence it costs less to generate more power in places like sunny California than it does cloudy Germany or Ontario. Yet for political reasons much infrastructure has been built in cloudy developed nations with highs of energy spending combined with mediocre levels of radiation. Cheap oil has discouraged use of solar power in the Middle East. Ownership: Solar is mostly a bipolar operation. It is either used by individuals to provide 20 to 60 per cent of their electrical needs or by large corporations and big utilities to generate hundreds of megawatts with massive installations. Supplying solar power owned and used by local communities for their own needs remains a largely novel idea. Community ownership would use less space, decentralize power distribution and possibly lower energy spending. Yet as one 2010 study noted few such experiments exist and "they often don't meet their objectives of providing clean, environmentally-friendly energy that is affordable for the community stakeholders." Materials: The making of solar photovoltaic cells requires rare elements such as gallium, tellurium, indium and selenium. Called "hitchhiker" metals, most are the byproduct of industrial copper, zinc or lead production. New thin-film solar sheets, for example, depend on indium. Moreover indium reserves are largely located in China and the U.S. Geological Survey predicts global supplies could be depleted within 10 years. Concentrated solar power which use mirrors to direct solar rays to heat water, also employs silver at rates of one gram per square meter. A global boom in such solar units would create silver shortages. Copper shortages are also a concern. Storage: Solar power offers intermittent bursts of energy, posing storage challenges. The average percentage of time a solar operation pours electricity onto the grid at full rated capacity ranges from 12 to 19 per cent. In contrast a coal-fired plant runs 70 to 90 per cent of the time. Storing sun-derived power in batteries, molten salts or compressed air schemes remains problematic if not costly due to significant energy losses in storage and release. Energy Density: Just as a slice of cheese offers more calories than a potato, different energy sources pack difference punches. The amount of energy contained in a solar ray versus a lump of coal is reflected in their respective geographical footprint. A 1,000 megawatt coal-fired plant requires 1 to 4 square km to mine and transport the coal. In contrast it takes 20 to 50 square km or the area of a small city to generate the same amount of energy from a photovoltaic farm. A large solar industry will compete with other land uses. Economic Volatility: Solar power is expensive to install and is only beginning to reach the same price levels as other electrical providers. The U.S. Department of Energy's SunShot Initiative, for example, seeks to reduce the cost of solar energy systems by 75 per cent by 2020. But investments in alternative energy sources also tend to be highly cyclical. When oil prices are high, communities, industry and government tend to divert dollars to renewables. But as soon as fossil fuel prices fall, that interest wanes and the renewable booms dissolves. Tom Murphy, U.S. physicist, solar advocate and energy blogger (Do the Math), argues that governments should "artificially" keep energy prices high enough "to maintain the impetus for developing alternatives, pumping the revenue into a national alternative energy infrastructure. But governments are bound by voters who simply don't want sustained high energy prices." — Andrew Nikiforuk

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"We had a lot of hopes and now we're more skeptical."

That's how Pedro Prieto, a 62-year-old global telecom engineer and solar entrepreneur, sums up Spain's famous solar revolution.

Spain's renewable dream, of course, began as sunny-multi-billion-dollar boom. Quasi-religious images of fields of photovoltaics and radiant concentrated solar towers wowed North American greens. (Concentrated solar uses 624 mirrors to focus radiation to a receiver that heats steam to drive a turbine.)

But the revolution rapidly collapsed into a messy economic bust that has left more questions than answers. Moreover, Prieto and his Spanish compatriots are still counting the unpredictable casualties of the nation's stalled energy transition.

Now the engineer is no stranger to solar power. As a telecom engineer he has worked with photovoltaic panels in remote locations since the 1970s. Nor is he a cheerleader for fossil fuels. As the co-founder of the Spanish Association for the Study of Energy Resources, Prieto has long advocated abandoning oil before its volatile pricing and pollution leave the globe in financial and atmospheric chaos.

Since 2004 he has designed, consulted and helped to build more than 30 megawatts (MW) of solar photovoltaic (PV) plants. He even manages, operates and partially owns a PV plant that spills one megawatt of juice (enough to power up to 1,000 homes) onto the national electrical grid in the province of Extremadura.

Given his vast technical experience Prieto also consults with governments around the world on solar renewable prospects. And he has also teamed up with ecologist Charles Hall to produce a provocative book: Spain's Photovoltaic Revolution: The Energy Return on Investment.

These days Prieto ends his presentations, more often than not, by asking to his audience to "pray for alternatives to nuclear."

Prieto is also the sort of guy that practically beams out inconvenient statistics. In 2007 installed solar power amounted to .0006 of the world's electrical consumption and did not keep pace with the growth of electric consumption.

Or as Prieto put it in 2008: "The Energy Consumption Chariot goes over 200 times faster than the Solar Power horses."

Spain, of course, has gained some fame and notoriety as a global solar pioneer. One-tenth in 2009 and one-fifteenth of the world's installed solar power modules now dot the Spanish countryside. But these expansive operations provide but 4.3 per cent of Spain's electricity.

The sun's sheer abundance has always made it the world's most popular renewable form of energy. Of all green alternatives solar energy is the only one whose potential harvest far outstrips the demand for fossil fuels. Enough radiation hits the earth every hour to meet all of the world's electrical needs for a year. By some very optimistic estimates the rapidly growing solar industry could account for 10 per cent of the world's electrical production by 2020.

Sunny climes

Spain, of course, gets more irradiation than any other European country. The nation's sunny plains and deserts absorb about 1,500 terawatt hours of solar energy every year. That represents at least three times more power than what Spain's 46 million citizens actually consume. (A terawatt hour by the way represents enough energy to operate one billion washing machines.)

But achieving that goal might come with some staggering financial costs, significant land disturbance as well as disappointing energy returns. Prieto has even come to view solar power in its current big industrial mindset as just "another extension of fossil fuels."

And he's not short of examples. The sun is renewable but photovoltaics are not. Just to make the silicon used to trap the sun's rays on manufactured wafers requires the melting of silica rock at 3,000 Fahrenheit (1,649 Celsius). And the electricity of coal-fired plants or ultrapurified hydrogen obtained from fossil sources provide the heat to do that. It also takes a fantastic amount of oil to make concrete, glass and steel for solar modules.

But Spain's interest in renewables is no mystery. Not only does the world's 14th economic power rely on fossil fuels more than any other European nation (consumption has doubled in the last decade), but it suffers from a 90 per cent dependency on foreign imports.

This energy servitude combined with the nation's concerns about climate change spurred an unusual revolution in 2004. That's when the government offered generous subsidies or premium tariffs for solar and wind-made electricity added to the national grid. The initiative guaranteed 25-year-long profitable returns of at about 20 per cent for solar entrepreneurs. The government also came up with an inviting mantra, "The Sun Moves Us."

Solar boom

Within short order farmers signed over orchards and plots of land for solar PV farms. Next came concentrated solar tower installations. Unlike Germany's solar revolution, which planted thousands of modules on rooftops, Spain focused its solar growth on installed ground facilities. They are, says Prieto, much more efficient and easy to maintain.

In response to the subsidies factories making silicon wafers and/or assembling modules popped up like orange trees across the nation. Sensing a financial killing, global banks and pension funds poured money into Spain's solar boom the same way they funded financial derivatives or the shale gas revolution in North America.

By 2008 Spain's solar explosion eagerly swallowed half of the globe's photovoltaic module production. Facing module shortages the country even started to import products from Germany, the U.S. and China.

This unexpected development undermined the goal of growing a renewable Spanish industry, says Prieto. (At one point China-based Suntech, the world's largest solar panel manufacturer, sold 40 per cent of its product to Spain. Last month Suntech declared bankruptcy.)

Meanwhile, the boom surpassed every government electrical target says Prieto. The government set an initial goal of creating 400 MW of power from solar power by 2010. But industry surpassed that goal in 2006-7. "Banks and investment funds treated solar like a financial product. These were the days of wine and roses."

But by 2008 the excesses of the boom became readily apparent. For starters, the government realized that it could no longer subsidize renewables for 25 years to the tune of 2.5 billion Euros a year.

And so it issued new royal decrees cutting promised returns from 46 cents a KW hour to 32 cents for investors. Later decrees forced more reductions putting brakes on the entire solar module industry.

"There have been 15 royal decrees on renewables since 2004," explains Prieto. "Each one tries to fix the unanticipated problems of the last one. Each one is worst than the last. But each decree makes renewables less credible." A raft of lawsuits has predictably clogged the courts.

The crash

An industry poised for a massive build-up based on guaranteed returns, explains Prieto, then laid off workers as a debt-heavy government cancelled or lowered promised financial returns from the sun. The solar PV sector now estimates that 44,000 of the nation's 57,900 installations are on the verge of bankruptcy.

During the solar "craziness" as Prieto calls it, other problems emerged too. Investors often planted installations of poor quality and design across the landscape. Many facilities weren't even located in the sunniest parts of Spain.

Spain's renewable boom (wind installations now make up 17 per cent of Spain's electricity supply with peaks covering up to 56 per cent) also created havoc with the nation's energy balance. Government investment in natural gas fired plants (a backup for intermittent wind) combined with renewables resulted in overcapacity in the system. Even the nation's nuclear power plants had to power down from 7.7 to 6.7 gigawatts for a while.

"The energy industry is much more complicated and integrated than anyone thought. The left side of Spain's energy planning brain didn't know what the right side was doing."

But what troubled Prieto most were the paltry energy returns of some 57,900 solar plants, both big and small. He reviewed Spain's excellent data on the energy outputs of the nation's solar network and than compared those findings to actual energy inputs. To his dismay Prieto found that solar offered only slightly better returns than biofuels. Or 2.4 to one.

"That is not enough to maintain society as it is today."

His finding surprised many researchers and for good reason. Previous studies put solar returns as high as eight or even up to 30 to one in some cases, or almost on par with conventional oil.

But most of this research used the same sort of best-case scenario modelling typically employed by car industry mileage studies. As long as the roads are flat, the fuel is good, the tires full and the driver competent, then great mileage can be achieved.

But real life experience can be different for car mileage as well as the energy output for solar installations.

Solar power, fossil fuel inputs

Spain discovered, for example, that the earth is rarely flat (a big issue for tracking and directing solar rays in the right direction). Moreover the modules (only 15 per cent efficient on average) rarely perform as expected. Not only do the panels require regular maintenance but constant cleaning to remove films of dust. And they only last 25 years.

But Prieto added together another 24 factors illustrating the industry's profound dependence on fossil fuels. They included road maintenance, rights of ways, module theft, intermittent loads, as well as the cost of natural gas fired back-up stations. In the end he concluded that the solar industry "eats and spends considerable energy."

Moreover countries such as Germany which receive but two-thirds of Spain's sunlight in the best case and on average deploy much less inefficient rooftop arrays will probably have returns one-fifth to one-third lower than Spain.

"Solar installations are dependent on a fossil fuel world and there are difficulties scaling up the power of the sun," says Prieto.

And what does Prieto think of big plans to industrialize the deserts of the U.S. southwest to provide power for the east? Or plans to colonize the Sahara desert of North Africa for European delights?

Not much, he replies sadly. The engineer calculates that just one plan proposed by former French prime inister Nicolas Sarkozy was so big that it was obsolete before it harvested one solar ray. The plan would have covered 400 sq. km of land and burned three to six million tons of coal to erect 1.8 to 3.6 million tons of steel and two to four million tons of glass. Vast amounts of clean water and lakes of desalinated water would have been needed to maintain the plants. Yet the plan would have generated only three per cent of the electricity that nations of the Mediterranean basin now consume. Such a scheme would exchange the political insecurity of oil and gas pipelines with high voltage cable lines.

"It would be far more rational to strive for a world with far lower levels of more localized demand and widely distributed, small and local generation and distribution networks where possible," the engineer concluded in a recent editorial.

Nations as solar plantations

Big Solar would also turn poor countries like Morocco into virtual solar plantations or colonies that feed electrical power to wealthy at a project cost of $60-billion. (Another unrealistic forecast suggests that industrial solar plants in the Sahara could produce enough energy for 100 million homes for half a trillion dollars by 2050. Prieto says this plan, dubbed Desertec would be lucky to achieve 30 per cent of Europe's electrical needs.)

But the big issue for solar is simply scaling up the enterprise to capture enough of the sun's rays to retire just a fraction of fossil fuels. Prieto calculates, for example, that to replace all electricity made by nuclear and fossil fuels in Spain would take a solar module complex covering 6,000 sq. km of the country at the cost the entire Spanish budget (1.2 billion Euros in 2007). It would also require the equivalent of 300 billion car batteries to store the energy for night-time use.

Prieto is not alone in reaching such sobering conclusions. A 2013 Stanford University report, for example, calculated that global photovoltaic industry now requires more electricity to make silicon wafers and solar troughs than it actually produces in return. Since 2000 the industry consumed 75 per cent more energy than it put onto the grid and all during its manufacturing and installation process.

Moreover it won't pay off this energy debt or energy consumed in its construction until 2016. As a consequence, ramping up of industrial solar production produces more greenhouse gases than it saves for nearly a decade. The study also recommended that reducing the fossil fuel inputs for a next generation of photovoltaic systems be a key priority.

"We have to leave oil before it leaves us," says Prieto paraphrasing the famous Fatih Birol quote, "and it is not good for nature or the planet."

Back to the village

"In my opinion we can use solar PV energy, as far as it is available and we can afford it for specific applications," says Prieto. But he now views solar PV systems as "non-renewable energy systems that can only capture a portion of the renewable energies temporarily."

Moreover there is no way solar power can sustain "our present wasteful way of living."

In Spain where nearly a quarter of the workforce sits idle and political unrest smolders in the cities, there is much talk about "La vida buena" or what the French call "decroissance" or degrowth.

The grassroots movement is all about living better by consuming less and sharing more. Prieto suspects the future may be determined more by behavior change than by investments in renewables.

"In general terms, I would suggest we make every possible effort to move towards a lower consumption and lower mobility society," sums up the 62-year-old.

"We need to deurbanize and localize as much as it is possible, and to return to the countryside, as much as it is possible, and to use more animal draft force."

When asked for advice on what other nations should do, Prieto thoughtfully pauses.

"It is difficult to give advice."