China flattens the duck with molten salt to generate solar power at night

[00:00:02]Good morning.

[00:00:04]Engineers in Sing Jang are deploying solar plants to produce power at nighttime.

[00:00:10]This new plant in the Gobi Desert uses molten salt to generate steam which turns turbines which in turn produce electricity for 8 hours after the sun goes down.

[00:00:23]It's 1 gawatt which is equal to the power demands from about 800,000 households.

[00:00:29]And this plant is novel and that it does not use batteries to store the excess power that's generated during the day.

[00:00:38]The problem with solar power is obvious.

[00:00:41]We use electricity all the time, but the sun is only shining half the time at most. On cloudy days, direct sunlight is hitting panels at lower intensity.

[00:00:51]Putting these power plants in the desert goes a long way to solving that problem, but it creates another that people don't live there. The giant population centers of China are mostly along the coast. So whatever power is generated there in Sing Jang needs to be sent across China to where people need it and where it's needed 24 hours a day, not just when the sun is up in West China.

[00:01:20]That new plant is the biggest in the world that uses molten salts instead of batteries. Batteries cannot yet do what these Chinese power engineers need them to, which is to store enough power affordably and then discharge at night affordably.

[00:01:38]This represents a problem for electricity grids across the world. The intensity of sunlight dictates how much electricity is produced directly by the solar element of the plant.

[00:01:50]And as a power grid builds out more and more solar capacity, that imbalance widens between the power produced during the day compared to at night.

[00:02:02]The result is called the duck curve.

[00:02:05]It's the sharp mismatch between peak solar generation and peak energy demand.

[00:02:12]When we put the data on a graph, the curve looks like a duck. The more solar intensive the energy source mix, the steeper the curves.

[00:02:23]In the morning, energy demand spikes as a human population wakes up.

[00:02:29]The intensity of the sunlight builds slowly and doesn't peak until a few hours later, resulting usually in huge overupp. The energy produced by solar around midday equals electricity demand and excess storage is possible theoretically.

[00:02:48]Then the sun goes down. At the same time, billions of people leave work and go shopping or go home.

[00:02:56]That's the time of day when the stress on a power grid is the most acute. from about 5:00 p.m. through 8:00 p.m. when power demand is far greater than what's coming off the solar panels, which by then is zero.

[00:03:14]There are several factors that this sing Jang plant has working strongly in its favor and also a couple of things that might challenge the economics of the project in the future. There are 260,000 tracking mirrors that cover 800,000 square meters. They follow the sun and reflect the sun's rays which are concentrated to heat salt to 550°.

[00:03:40]Then the molten salt goes on to create the steam which turns the turbines to produce electricity.

[00:03:48]Liquid salt is already a medium for that power generation system. It's used in fossil fuel plants already and even in nuclear plants where molten salt is pumped through the reactors to absorb heat which is then used again to turn turbines.

[00:04:06]The reflectors at the Hami plant are flat. That makes them less efficient than curved mirrors. But flat mirrors are less expensive to build and to maintain.

[00:04:18]Efficiency drops by more than half.

[00:04:21]But the plant managers believe that the far lower upfront and ongoing maintenance costs justify the lower solar efficiencies.

[00:04:30]The data for the levelized cost of electricity figures will come in over time, but plant developers estimate that the power will produce at the same cost as Chinese coal.

[00:04:46]Advantage number two is geography. China is one single time zone, but could just as easily be four. China is enormous, and the sun is shining brightly in Sing Jang Province long after the sun has gone down in East China. That is power that can still be fed directly onto the grid. And that's because the infrastructure is already in place to transport that electricity produced in Sing Jang to where it's needed.

[00:05:15]China's ultra-igh voltage direct current network is the largest in the world and it's what makes the whole system possible and also helps explain how China's electricity mix is more diverse than almost anyone else's and how electricity prices here are falling year over year over year despite booming demand for the power.

[00:05:39]The new plant is on just one of those lines in that network and it displaces 38 million tons of coal demand elsewhere on the grid.

[00:05:51]And there is another plant coming which is 50% larger and will be located nearby the plant that just opened.

[00:06:02]The economics of these new plants work very favorably today, but there are some unknowns that may change that math.

[00:06:10]Flat mirrors do cost less to build and maintain than curved mirrors, but there are a quarter of a million tracking mirrors with lots of moving parts, and we don't have a lot of historical data yet to know the long-term maintenance and repair costs for those at a commercial scale.

[00:06:29]We should figure those costs to be a lot lower in China than anywhere else.

[00:06:34]But the second challenge may come from further improvements in battery storage and falling costs there.

[00:06:41]Battery efficiency is rising fast while their costs are falling fast.

[00:06:48]It took decades for that to play out, but over time we now see the results. 15 years ago, battery pack prices were 12 times higher compared to today.

[00:07:00]that has in turn enabled the batteryification of everything.

[00:07:10]For now, it is more cost effective for China's solar farms in Sing Jang to use molten salt to store the excess energy that they collect at those low points in the duck curve.

[00:07:24]But as battery prices continue to fall, the economics of that might change.

[00:07:30]So the overall cost of operating those systems are only going to fall over time. And whether the excess power will drive big turbines or stored in big batteries, it'll be Chinese companies that build them.

[00:07:45]That's to say that any country with lots of empty space and lots of sunlight can transform those areas into power plants and they will turn to Chinese engineers and Chinese companies to build them. The solar panels, the turbines, all that hardware for building out the long distance power transmission networks, all that business will go through here.

[00:08:09]This is Sing John.

[00:08:11]Be good.