Could These 2 Breakthroughs Solve Solar Power's Biggest Problem?

Solar power promises nearly limitless, clean, and renewable power. However, modern solar technology has two major problems that threaten its usefulness: high cost and not providing power at night. This article highlights two innovative solutions that aim to solve these limitations and allow solar power to maximize its potential for a cleaner, greener tomorrow.

Aug 17, 2014 at 11:03AM

Editor's note: A previous version of this article stated that it would require 214 million Gemasolar stations to meet the world's energy needs, when in fact it would only require 214,000.

Solar power holds the theoretical potential to solve all the world's energy problems. For example, in just one hour the sun shines enough light on the earth to power the world for a year.

The problem is harnessing this nearly limitless, clean, and renewable power when and where we need it. I recently wrote about Japan's innovative efforts at solar space-based power. This article brings the concept of solar breakthroughs down to earth and looks at two exciting technologies that could allow solar power to come into its own as a practical future power source.

Solar power at night
One of the major weaknesses of solar power is that it's intermittent. Clouds, storms, and the setting of the sun can lower or eliminate power output. This means that traditional power sources such as gas, nuclear, or coal are required to maintain a base load. 

Concentrated Solar Power, or CSP, potentially offers a way around this issue by combining solar power with mirrors and a liquid energy storage medium. 

Gemasolar Project
Source: Torresol Energy 

Terrosol Energy, a Spanish concentrated solar company, has designed the Gemasolar station to generate 20 megawatts of power -- enough for 30,000 homes. 

Mirrors, a total of 2,650 of them, concentrate sunlight by a factor of 1,000 onto a tower where molten salts are heated to 1,050 degrees Fahrenheit. The molten salts can be stored in tanks and used to generate steam to spin electricity generating turbines up to 15 hours after the sun has set. This technology allows for solar power to be generated around the clock and has a capacity factor of 75% (generating maximum output 75% of the time). This is in between gas-fired power plants, whose capacity factors range from 25%-50%, and nuclear plants which run at 90% of maximum capacity.

All told Gemasolar can produce 60% more power than a similarly sized solar panel installation, but there are two problems with the design. First, the size of the installation is enormous, requiring 480 acres of land. Given that in 2012 global power demand was 23,500 TWh, this means to generate all the power demanded by the world using this design would require around 214,000 Gemasolar stations and take up 103 million acres of land.

Second, the cost of the station is estimated to have been $260 million, or $13 billion per GWh of capacity. To put that into perspective it's 2.7 times as expensive as traditional solar power and 13 times as expensive as gas-fired power.

Gemasolar is expected to achieve a positive return on investment in 18 years, but Terrasol Energy is attempting to bring down the cost by scaling up concentrated solar with its Valle 1 and 2 plants, which together generate 100 megawatts of power, enough for 80,000 homes.

Source: Torresol Energy

Unlike the tower design of the Gemasolar station, the Valle power stations use a parabolic trough design. Sunlight is focused onto a glass


parabolic concentrated solar source Torresol Energy

tube containing thermal oil, which is then heated and used to generate steam. Like the tower design, this technique can generate power when the sun isn't shining and the cost is 44% less per gigawatt of capacity than the Gemasolar station. Unfortunately this method also has major drawbacks. 

For one, the cost, though lower, is still $7.3 billion per gigawatt. Second, the area required is mind-boggling with a total of 1.1 million square meters of solar collectors. Finally, the heat storage capacity of this system is just 7.5 hours, meaning it can only operate around 4,000 hours per year, vs 6,000 for the solar tower design of Gemasolar (and 2,000 hours for traditional solar technology).

Concentrated solar may offer a way for solar to provide all day power, but its enormous land area requirements and uneconomical cost make it unlikely to ever solve the world's power needs.

Massive solar cost savings needed
A Durham, North Carolina start-up called Semprius is working on a way of stacking miniature solar cells (each just a millimeter across) together to achieve unheard of efficiency and cost savings. By growing layers of different semiconductor materials, each capturing a different frequency of light, the company has been able to build a solar cell with 44.1% efficiency. Semprius thinks it can eventually achieve efficiency beyond 50% (double current solar cell efficiency) within three to five years.

According to Scott Burroughs, vice president of technology at Semprius, with sufficient economies of scale his company's technology could result in solar power costing just five cents/KWh. That's 22% less than the cost of a new gas-fired power plant (6.4 cents/KWh) according to the U.S. Energy Information Administration.

Solar power, despite its amazing potential, still has a long way to go to overcome its two largest hurdles -- constant output and high cost. However, advances in innovative solar engineering techniques and material sciences are helping to solve those issues and may one day usher in an era where the sun may be all we need to power the world.

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4 in 5 Americans Are Ignoring Buffett's Warning

Don't be one of them.

Jun 12, 2015 at 5:01PM

Admitting fear is difficult.

So you can imagine how shocked I was to find out Warren Buffett recently told a select number of investors about the cutting-edge technology that's keeping him awake at night.

This past May, The Motley Fool sent 8 of its best stock analysts to Omaha, Nebraska to attend the Berkshire Hathaway annual shareholder meeting. CEO Warren Buffett and Vice Chairman Charlie Munger fielded questions for nearly 6 hours.
The catch was: Attendees weren't allowed to record any of it. No audio. No video. 

Our team of analysts wrote down every single word Buffett and Munger uttered. Over 16,000 words. But only two words stood out to me as I read the detailed transcript of the event: "Real threat."

That's how Buffett responded when asked about this emerging market that is already expected to be worth more than $2 trillion in the U.S. alone. Google has already put some of its best engineers behind the technology powering this trend. 

The amazing thing is, while Buffett may be nervous, the rest of us can invest in this new industry BEFORE the old money realizes what hit them.

KPMG advises we're "on the cusp of revolutionary change" coming much "sooner than you think."

Even one legendary MIT professor had to recant his position that the technology was "beyond the capability of computer science." (He recently confessed to The Wall Street Journal that he's now a believer and amazed "how quickly this technology caught on.")

Yet according to one J.D. Power and Associates survey, only 1 in 5 Americans are even interested in this technology, much less ready to invest in it. Needless to say, you haven't missed your window of opportunity. 

Think about how many amazing technologies you've watched soar to new heights while you kick yourself thinking, "I knew about that technology before everyone was talking about it, but I just sat on my hands." 

Don't let that happen again. This time, it should be your family telling you, "I can't believe you knew about and invested in that technology so early on."

That's why I hope you take just a few minutes to access the exclusive research our team of analysts has put together on this industry and the one stock positioned to capitalize on this major shift.

Click here to learn about this incredible technology before Buffett stops being scared and starts buying!

David Hanson owns shares of Berkshire Hathaway and American Express. The Motley Fool recommends and owns shares of Berkshire Hathaway, Google, and Coca-Cola.We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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