In China, there are over 30 Ultra High Voltage lines in operation, linking renewable energy in the country's west where power is generated to wider consumers on the east coast. 

To balance supply and demand in real time, all the power grids need to make sure that the plants generate not too much, not too little electricity. 

But things often don't go as expected. Not all renewable electricity can get on those lines. Fossil fuels and even hydro can instantly adjust output as desired. But solar and wind are difficult to control, because of the ever-changing situations of their sources.

So, once too much or too little renewable energy enters the system, the grid can fluctuate, or even collapse, leading to a waste of solar and wind energy.

The good news is that we have seen some inspiring improvement. Most countries tackle this by keeping more reliable sources of energy production in reserve. 

Take the Taizhou Power Plant in Jiangsu Province for an example. Since the new energy has relatively large volatility, the entire power grid will have a changing volumes according to each time period. 

Therefore, the relatively stable thermal power will be complementary at this time, and the mission of power generation will continue to be completed by means of deep peak regulation.

The Gigawatt-level generating units can accept instructions and carry out deep peak regulation. To be specific, if the wind drops or when the sun dips beneath the horizon, these units will be ready to ramp up their production. In turn, these powerful generators will keep a low profile. 

In the end, it's still a new, efficient way of using fossil fuels, which means we still need fossil fuels to achieve net zero emissions.

To know more stories about carbon neutrality, check out the rest of CGTN's documentary Human Carbon Footprint.