Energy Use and Solar Panel Production in China and America
By Red Sox Steve
VagabondGuru.com
I spent October and November 2010 in China - I've seen the largest green energy project in the world (Three Gorges Dam), rode high-speed trains all around the country, and took the Middle Kingdom's impressive public transportation system in every city I visited. I didn't take pleasure cruises or use high-end travel services; I walked the streets and rode the subways and busses.
I see, I learn, I process and think. I do it all for my edification and yours - those willing to ponder the 22nd and 23rd centuries, at least.
How we produce renewable energy is essential to that future, and it's why I write about it today.
China and the United States are the two largest greenhouse gas producers in the world, together responsible for around 40% of global greenhouse gas production. This is the direct result of converting nonrenewable resources like coal, oil and natural gas into electricity. China and the US are also among the top four nations (Russia and India are the other two) holding 60% of global coal reserves. 70% of China's energy comes from burning coal, and in the US, 46%.1
In absolute terms, we see more distinctions: Each year, the sum of human activity puts 37 billion tons of CO2 in the earth's atmosphere; two decades ago, it was less than 25. On average, an American puts 25 tons of CO2 into the atmosphere each year, and a Chinese person puts 8. America's per capita electricity use is 13.6 megawatt hours/year, while China's is less than 3.2 China's total energy consumption as of 2009 is 2,234 Mtoe (Million "Tonnes of Oil Equivalent", energy produced from burning one ton of oil), while the United States consumed 2,201 Mtoe. The next closest was India with a distant 655.3
In both nations, non-renewable resources make up a huge percentage of energy production, and renewable resources, such as solar panels, make a small contribution - In each of China and the United States, solar panels make up less than 10% of energy production.
China's economy has been growing for about 3 decades, and this growth can be traced back to market reforms initiated by Deng Xiaopeng in 1978. Thereafter, China's economic output grew quickly, steering millions away from the agrarian lifestyle they had known for generations. China started to become heavily dependent on the burning of minerals and fossil fuels; its yearly energy consumption has more than quadrupled since the 1980s. By the early 1990s, construction on the Three Gorges Dam had begun (oil prices were at a then record high), and China's commitment to renewable energy hasn't wavered since.
Today, China's fast growing economy is accompanied by some sobering public health statistics - 16 of the top 20 most polluted cities in the world are in China4, and cancer is one of the nation's leading causes of death.5 During my visits to cities as far north as Harbin and as far south as Guangzhou, it became typical to see a hazy skyline when viewing the cityscape - as if the sun wasn't shining brightly on even the clearest days.
By the start of the 21st century, construction on the Three Gorges Dam was proceeding apace, but was still more than a half decade from completion. The 18,200 MW it was forecast to produce would make a sizable dent in China's fossil fuel consumption, but more renewable sources were needed. Around that time, the Chinese turned to solar production in a big way.
The largest producer of solar panels anywhere in the world today is a company called Suntech, headquartered in Wuxi, Jiangsu Province, China, just an hour's train ride from Shanghai. Let's have a glance at highlights taken from an article about the company6:
- Zhengrong Shi, CEO of Suntech, earned a Ph.D in solar power technology in the mid 1990s from Australia's University of New South Wales, and after working in Australia for a few years, returned to China in 2000, founding Suntech in 2001.
- Suntech's first factory opened in 2002, and has since cut solar panel production time significantly.
- In 2007, only 2% of global solar panel production came from China. In 2010, that number was 42%.
- Per Watt production costs have dropped from $3.20 in 2004 to $1.28 in 2010 for Chinese manufacturers.
According to the article and a related video7, the main component behind Suntech's solar panels is a molecule called "multicrystalline silicon". Multicrystalline silicon is a silver metal with an irregular crystal structure. In other words, the locations of, and distances between, silicon atoms is not uniform throughout the molecule; the irregularity lends itself to an unpredictable path for electron travel. Carrying this one step further, the unpredictability of an electron's path has ramifications in the efficiency of a solar panel's ability to convert incoming light to electric current. The movement of electrons through an irregular crystal structure is similar to telling a blindfolded person to navigate a maze without hitting a wall - very few make it all the way through.
Suntech's multicrystalline silicon technology has broken its own record for solar cell efficiency and is currently more than 17% efficient, the highest in the world. However, there is a technology being investigated at UNSW, which is discussed in the video interview: solar panels that use the PERL method. PERL stands for "Passivated Emitter and Rear Locally diffused". In an upgrade from widely used solar-cells that use doped silicon, and reflect light back out of the solar cell, PERL technology captures more of those escaping photons.
Here is a link to the white paper that contains the above schematic: PERL technology. The front edge of the solar panel is coated (industry term: "passivated") with an anti-reflective surface, preventing photons from bouncing back out of the solar panel once inside. The coating is a metal-oxide substance that can be one of two types: "SLAR" or "DLAR" - "Single-layer anti-reflective" or "Double-layer anti-reflective". According to Suntech's CEO, PERL technology has achieved 25% efficiency for about 20 years.
Until the last couple of years, when UNSW started collaboration with Suntech to commercialize PERL-based solar cells, PERL had no economic viability. One of the main obstacles was found in the panel production process. As stated in the video - the front (sun-facing side) of solar cells are coated with narrow metal lines that collect electrical charge. According to Dr. Stuart Wenham, Suntech's CTO, these narrow lines are actually too wide, reducing the amount of light retained, and thus reducing efficiency of the solar cell. Dr. Wenham concludes that the metal lines placed on solar cells must be one-sixth (from 120 microns wide to 20 microns wide) as wide as they currently are to effectively use the highly efficient PERL technology and make it commercially viable.
According to a 2009 whitepaper released by Suntech 8, they have successfully changed some of the processes and materials associated with PERL production and have "whittled" the width of the metal lines down to 25 microns, as compared to 20 microns in PERL solar cells; these lines are spaced less than 1mm apart, which is exactly the spacing found in PERL solar cells. As a result, Suntech has achieved greater than 18% efficiency9 (verified by an outside source) and has been marketing the new solar cells under the trademark "Pluto".
China and America continue to be - far and away - the largest energy consumers on earth, and are consequently its biggest polluters as well. Over the last couple of decades as the Chinese economy has grown rapidly, the Chinese have evidenced a commitment to renewable energy through massive projects like the Three Gorges Dam. Companies like Suntech fit perfectly under this umbrella - they mass produce solar cells and continue to add layers of understanding and improvement to solar cell technology, pulling in well-understood research and attempting to commercialize it. The concepts I've discussed above are merely the beginning of the renewable energy revolution mankind needs to meet the energy requirements of the future.
Sources:
1, 2. "Dirty Coal, Clean Future", Atlantic Monthly, December 2010
3. http://yearbook.enerdata.net/
4. China's View of Climate Change by Ying Ma, Policy Review, June & July 2010
5. http://www.earth-policy.org/data_center/C21
6. "Solar's Great Leap Forward", Technology Review, July/August 2010
7. http://technologyreview.com/video/?vid=581
8, 9. http://am.suntech-power.com/images/stories/pdf/other/pluto_whitepaper.pdf
