The challenge of storing energy year-round has been one of the biggest obstacles to the widespread adoption of green power. However, Polar Night Energy has developed the world’s first fully functional commercial sand battery, which could offer a low-cost, eco-friendly solution to the storage problem. It is the first commercial sand battery in the world, and it was built in Kankaanpaa, Finland in 2022.

Dr. Natalia Schiff, expert of Polar Night Energy, says that sand battery works by heating sand up to high temperatures (at around 500℃) using renewable energy, such as solar or wind power. The hot sand can then be stored for months or even years, and then discharged to provide heat or electricity when needed.

The Polar Night sand battery has a capacity of8 megawatt hours (MWh) of thermal (热量的) energy, and it can discharge about 200 kilowatts (kW)of power. This means that it can provide heat for about 4,000 homes for a day, or it can generate enough electricity to power about 100 homes for a day.

Sand battery is relatively inexpensive to build, and it is compatible (兼容的) with a wide range of renewable energy sources. It also can be built in larger sizes to store more energy, which is a promising new technology for storing renewable energy.

Sand batteries could be a valuable tool to combat climate change. They could help to make renewable energy more reliable and available, which would reduce our reliance on fossil fuels. They could also be used to provide heat in areas that are not connected to the electricity.

As the world transitions to a clean energy future, sand batteries could play an important role in helping to balance the energy and ensuring that we have a reliable source of energy when we need it.

China’s Yutu 2 Rover, which was crossing a crater (环形山) on the far side of the moon, discovered a mysterious, cube-like structure in November as it scanned the skyline. The unknown structure seemed to be located around 260 feet away from where the Rover crossed.

Our Space, associated with the Chinese National Space Administration which controls Yutu 2, first noted the object in a post on December 3rd; the story gave a nickname to the object “mystery hut”. Yutu 2 has since adjusted course to check out the cube, and will spend the next 2 to 3 lunar days investigating this mysterious moon feature.

The Yutu 2 Rover launched with China’s Chang’e 4 mission in 2018, and reached the moon in January 2019. The mission aimed to discover more about the far side of the moon, or as pop culture calls it, the “dark side” of the moon. Contrary to this nickname, the far side of the moon is not actually always dark, it just faces away from the Earth. The rover, solar powered, goes into a kind of hibernation (休眠) when the sun sets on the far side of the moon, and wakes up to work when the sun rises over the crater.

Yutu 2 has seen plenty of interesting moon features in its travels already, including a strange gel (胶状物) that turned out to be some rocks melted together, and some pieces that were likely to be from the impact of a meteor (流星). The Chang’e 4 mission has also brought forth some fascinating new discoveries like what could be pieces of the moon’s mantle (覆盖层).

Whatever this structure turns out to be, Yutu 2 will continue uncovering other secrets the “dark side” of the moon is holding.

At every turn in the Netherlands, the future of sustainable(可持续的) agriculture is taking shape—not in the meeting rooms of big companies but on thousands of modest family farms.

You can see it vividly on the farm run by Ted Duijvestijn and his brothers. At the Duijvestjns' 36-acre greenhouse near the old city of Delf, visitors wander among the deep green tomato plants, 20 feet tall. Rooted not in soil but in materials made from leaves and stalks, the plants are heavy with tomatoes—15 varieties in all—to suit the taste of the most demanding customers.

Since 2004, the Duijvestijns have declared resource independence on every front. The farm produces all of its own energy and fertilizer and even some of the packaging materials necessary for the crop's distribution and sale. The growing environment is kept at perfect temperatures year-round by geothermal heat(地热) that can be found under at least half of the Netherlands. Only rainwater is used for irrigation. Each kilogram of tomatoes from their plants requires less than 15 kilograms of water, compared with 61 kilograms for plants in open fields. Once each year the entire crop is regrown from seeds, and the old plants are processed to make packaging materials. The few pests that manage to enter the greenhouse are greeted by an army of fierce insects that shows no interest in tomatoes. The nutrition in the soil can be improved by growing plants that work with certain bacteria to produce their own fertilizer. In short. it's an entirely self-contained food system.

“Look at the island of Bali in Indonesia!” Ted explains. “For at least a thousand years, its farmers have raised ducks and fish within the same rice field. It's irrigated by the canal systems sculpted by human hands along mountains. They are our model.”