How much clean energy does the world need? In the solar power generation olympics, as of 2017, the US takes the bronze medal. China wins the gold, and India is in second place with silver.
The world’s largest solar farm covers 10 square miles and now has 4 million solar panels. It’s the Longyangxia Dam Solar Park in China, which has the capacity to generate 850 megawatts of electricity — enough to power roughly 140,000 homes.
Here’s what the complex, built in 2013, looked like then compared to how it looked in January 2017.
Last year, China invested $103 billion into renewable energy, and in 2016, its total installed capacity was 77 gigawatts, which pushed the country well ahead of other leaders in renewables such as Germany, Japan, and the US.
However, Longyangxia may not be the largest solar power plant for long. According to Bloomberg, there is a project planned for the Ningxia region of Northwest China which will have a capacity of 2000 megawatts when it’s completed.
The solar power station is integrated with the Hydroelectric power station. The park is coupled to one of the hydroelectric turbines, which automatically regulate the output to balance the variable generation from solar before dispatching power to the grid. This limits the problems connected to variable solar generation while helping to conserve water.
The solar park is coupled directly to one of four turbines at the nearby 1,280MW hydro station …
China has set a target of 70GW by 2020 of pumped storage capacity, of which over 27GW is currently under construction.
Water in the dam’s 24.7 billion m3 reservoir provides irrigation water for up to 1,000,000 hectares (2,471,054 acres) of land.
How does the largest US solar plant compare? Here is a list of solar stations with an output above 150 megawatts. In terms of capacity of single solar plants, with Longyangxia, China’s 850 MW plant beats the US’s largest by 272 megawatts.
Solar Star is a 579-megawatt (MWAC) photovoltaic power station near Rosamond, California. When completed in June 2015, it was the world’s largest solar farm in terms of installed capacity, using 1.7 million solar panels, made by SunPower and spread over 13 square kilometers (3,200 acres)
Some types of solar modules in use move automatically to track the sun, maximizing collection, like sunflowers:
At dawn, whole fields of sunflowers stand at attention, all facing east, and begin their romance with the rising sun. As that special star appears to move across the sky, young flowers follow its light, looking up, then over and westward, catching one final glance as the sun disappears over the horizon.
At night, in its absence, the sunflowers face east again, anticipating the sun’s return.
They do this until they get old, when they stop moving. Then, always facing east, the old flowers await visits from insects that will spread their pollen and make new sunflowers. Those flowers too, will follow the sun.
Heliotropism, a growth movement in plants induced by sunlight, is sometimes called solar tracking. Alfalfa, cotton, soybean, bean, and some wild species of the mallow family Malvaceae exhibit solar tracking, a directional response to the sun. (Link)
For generating electricity from the sun, there are different technologies humans use currently.
Compared to other photovoltaic plants of similar size, Solar Star uses a smaller number (1.7 million) of higher efficiency arrays, mounted on single axis trackers. In contrast, the Desert Sunlight Solar Farm and the Topaz Solar Farm (550 MW each) use a larger number (roughly 9 million) of non-tracking CdTe photovoltaic modules rather than conventional crystalline silicon PV technology, spread over a larger area (about 25 square kilometers). Both approaches appear commercially viable.
More about the cadmium technology:
Cadmium telluride (CdTe) photovoltaics describes a photovoltaic (PV) technology that is based on the use of cadmium telluride, a thin semiconductor layer designed to absorb and convert sunlight into electricity. Cadmium telluride PV is the only thin film technology with lower costs than conventional solar cells made of crystalline silicon in multi-kilowatt systems.
On a lifecycle basis, CdTe PV has the smallest carbon footprint, lowest water use and shortest energy payback time of all solar technologies. CdTe’s energy payback time of less than a year allows for faster carbon reductions without short-term energy deficits.
Could all human energy consumption become renewable?
As of two years ago in 2015 renewable was starting to gain in the big picture of total human energy consumption.
When I started writing for The Motley Fool in 2010, the solar power industry was small, and the cost to manufacture a solar panel was about $1.10 per watt, meaning buying a panel on the open market would cost you around $1.60 per watt. In 2017, solar panel prices hit $0.40 per watt on the spot market, a quarter of their cost just seven years earlier, and a much faster cost reduction than anyone had predicted. It’s no coincidence that between 2010 and 2016 solar installations globally nearly quintupled from 16 GW to 74 GW.
Let’s say some aliens land. They speak your language. They offer humanity a perpetual clean worldwide power supply, and they ask you how much power the earth needs per year. What would you tell them? In 2012, we used under 105,000 TWh total harnessed energy from all sources.
Major energy production or consumption is often expressed as terawatt hours for a given period that is often a calendar year or financial year. One terawatt hour is equal to a sustained power of approximately 114 megawatts for a period of one year.
In that case, a sustained 11,970,000 megawatts (11.97 terawatts) would have taken care of the earth five years ago.
So, the obvious answer is to multiply that by 1000 so we have enough energy every day to clean up the world and expand. Of course, you’d want to rub your neck and mention to the aliens that we don’t all get along very well here on earth and so the new 12 petawatt continuously available power source should be safe, very widely and fairly distributed, and untamperable.
What is the total possible power we could collect from the sun on earth? The power we get differs by location and time of year.
A conservative estimate assumes we will be able to generate an average 2 kilowatt hours per square meter. What portion of the earth’s 149 trillion square meters of land mass might be harnassed for solar collection? Let’s say we want 18 TW:
Here’s an overview over how much area has to be covered in photovoltaics (solar cells) to cover the entire World’s energy consumption (based on an assumption of an electricity conversion rate of 8%):
It appears that we could cover the entire world’s energy needs with solar power. Perhaps we don’t need the help of benevolent aliens, just the foresight, organization and motivation to make clean energy a global priority.