A Better Flow Battery

Stanford Scientists Advance New Way to Store Wind and Solar Electricity on a Large Scale, Affordably and at Room Temperature
A new type of flow battery that involves a liquid metal more than doubled the maximum voltage of conventional flow batteries and could lead to affordable storage of renewable power

By Mark Golden, Stanford News Service

July 19, 2018 -- A new combination of materials developed by Stanford researchers may aid in developing a rechargeable battery able to store the large amounts of renewable power created through wind or solar sources. With further development, the new technology could deliver energy to the electric grid quickly, cost effectively and at normal ambient temperatures.

The technology – a type of battery known as a flow battery – has long been considered as a likely candidate for storing intermittent renewable energy. However, until now the kinds of liquids that could produce the electrical current have either been limited by the amount of energy they could deliver or have required extremely high temperatures or used very toxic or expensive chemicals.

Stanford assistant professor of materials science and engineering William Chueh, along with his PhD student Antonio Baclig and Jason Rugolo, now a technology prospector at Alphabet’s research subsidiary X Development, decided to try sodium and potassium, which when mixed form a liquid metal at room temperature, as the fluid for the electron donor – or negative – side of the battery. Theoretically, this liquid metal has at least 10 times the available energy per gram as other candidates for the negative-side fluid of a flow battery.

“We still have a lot of work to do,” said Baclig, “but this is a new type of flow battery that could affordably enable much higher use of solar and wind power using Earth-abundant materials.”

The group published their work in the July 18 issue of Joule.

Separating sides

In order to use the liquid metal negative end of the battery, the group found a suitable ceramic membrane made of potassium and aluminum oxide to keep the negative and positive materials separate while allowing current to flow.

The two advances together more than doubled the maximum voltage of conventional flow batteries, and the prototype remained stable for thousands of hours of operation. This higher voltage means the battery can store more energy for its size, which also brings down the cost of producing the battery.

“A new battery technology has so many different performance metrics to meet: cost, efficiency, size, lifetime, safety, etc.,” said Baclig. “We think this sort of technology has the possibility, with more work, to meet them all, which is why we are excited about it.”

Improvements ahead

The team of Stanford PhD students, which in addition to Baclig includes Geoff McConohy and Andrey Poletayev, found that the ceramic membrane very selectively prevents sodium from migrating to the positive side of the cell – critical if the membrane is going to be successful. However, this type of membrane is most effective at temperatures higher than 200 degrees Celsius (392 F). In pursuit of a room-temperature battery, the group experimented with a thinner membrane. This boosted the device’s power output and showed that refining the membrane’s design is a promising path.

They also experimented with four different liquids for the positive side of the battery. The water-based liquids quickly degraded the membrane, but they think a non-water-based option will improve the battery’s performance.

https://news.stanford.edu/press/view/22184

Early Internal Combustion Engine

The Pyréolophore was one of the world's first internal combustion engines. It was invented in the early 19th century in Chalon-sur-Saône, France, by the Niépce brothers: Nicéphore (who went on to invent photography) and Claude. In 1807 the brothers ran a prototype internal combustion engine, and on 20 July 1807 a patent was granted by Napoleon Bonaparte after it had successfully powered a boat upstream on the river Saône.

The Pyréolophore ran on what were believed to be "controlled dust explosions" of various experimental fuels. The fuels included mixtures of Lycopodium powder (the spores of Lycopodiu, or clubmoss), finely crushed coal dust, and resin.

Operating independently, in 1807 the Swiss engineer François Isaac de Rivaz built the de Rivaz engine, a hydrogen-powered internal combustion engine. These practical engineering projects may have followed the 1680 theoretical design of an internal combustion engine by the Dutch scientist Christiaan Huygens. The separate, virtually contemporaneous implementations of this design in different modes of transport means that the de Rivaz engine may be correctly described as the first use of an internal combustion engine in an automobile (1808), whilst the Pyréolophore was the first use of an internal combustion engine in a boat (1807).

Proof of Concept

In 1807 the brothers constructed and ran a prototype internal combustion engine, and received a patent for ten years from the Bureau of Arts and Trades (French: Bureau des Arts et Métiers) in Paris. The patent was signed by Emperor Napoleon Bonaparte and dated 20 July 1807, the same year that Swiss engineer François Isaac de Rivaz constructed and ran a hydrogen-powered internal combustion engine. It is not clear how much these practical engineering projects owe to the theoretical designs of 1680 by the Dutch scientist Christiaan Huygens.

The Pyréolophore ran on controlled dust explosions of various experimental fuels, including various mixtures of finely crushed coal dust, Lycopodium powder, and resin. De Rivaz, meanwhile, was using a mixture of hydrogen and oxygen.

To prove the utility of the Pyréolophore to the patent commission, the brothers installed it on a boat, which it powered upstream on the river Saône. The total weight was 2,000 lb (910 kg), fuel consumption was reported as "one hundred and twenty-five grains per minute" (about 8 grams or 0.28 ounces per minute), and the performance was 12–13 explosions per minute. The boat was propelled forward as the Pyréolophore sucked in the river water at the front and then pumped it out towards the rear. Thus, the Commissioners concluded that "the machine proposed under the name Pyreolophore by Mm. Niépce is ingenious, that it may become very interesting by its physical and economical results, and deserves the approbation of the Commission.”

Operation

The operation of the Pyréolophore was first described in a meeting at the Academy of Sciences on 15 December 1806. Lazare Carnot noted that "there was a bright flash of the 'spores of lycopodium' inside their sealed copper machine... The Niépce brothers, by their own device and without using water, have managed to create a commotion (explosion) in a confined space which is so strong that the effects appear to be comparable to a steam engine or fire pump".

The Pyréolophore operated as a series of discrete burns at a frequency of about 12 per minute to power a boat. Power was delivered in pulses, each pulse forcing water from the engine's tail pipe set under the boat and pointing towards its stern. The boat was pushed forward at each pulse by the reactive force of the ejected mass of water.

A Pyréolophore engine consists of two principal interconnected chambers: a firelighting chamber and a combustion chamber. There is also a bellows for injecting air, a fuel dispenser, an ignition device, and a submerged exhaust pipe. There is a means of storing energy at each explosion in order to work the mechanism as it prepares itself for the next cycle.

A mechanically operated bellows injects a jet of air into the first chamber where ignition will take place. Mechanical timing lets fall a measured amount of powder fuel into the jet so that it is blown along and mixed with it. Under the control of the mechanical timing mechanism a smoldering fuse is introduced to this fuel air jet at the precise moment it passes the fuse location. The fuse then withdraws behind a metal plate. The now burning ball of powder and air travels through a wide nozzle into the main combustion chamber where a fast, almost explosive, burn takes place. The whole system now being almost airtight, a build-up of pressure follows. The pressure acts against the column of water in the exhaust pipe and expels it from the system. As the flow of exhaust gas moves into the tail pipe, it moves a loose piston in the combustion chamber which extracts and stores sufficient power to work the machine's timing mechanisms. Energy from this piston is stored by lifting weights attached to a balance wheel. The return of this wheel to its lower position under the pull of the weights governs the timing for the next cycle by operating the bellows, fuel dispenser, the fuse and valves at the correct points in the cycle. The tail pipe, being under the boat, fills with water ready for the next discharge. The fall of the timing piston also expels the exhaust gases via a pipe above the ignition chamber, which is closed off by a valve during the burn part of the cycle.

https://en.wikipedia.org/wiki/Pyr%C3%A9olophore

12 More Jupiter Moons

A Dozen New Moons of Jupiter Discovered
Bringing the Total Number of Jovian Moons to 79

Washington, DC— July 16, 2018 -- Twelve new moons orbiting Jupiter have been found—11 “normal” outer moons, and one that they’re calling an “oddball.”  This brings Jupiter’s total number of known moons to a whopping 79—the most of any planet in our Solar System.

A team led by Carnegie’s Scott S. Sheppard first spotted the moons in the spring of 2017 while they were looking for very distant Solar System objects as part of the hunt for a possible massive planet far beyond Pluto.  

In 2014, this same team found the object with the most-distant known orbit in our Solar System and was the first to realize that an unknown massive planet at the fringes of our Solar System, far beyond Pluto, could explain the similarity of the orbits of several small extremely distant objects. This putative planet is now sometimes popularly called Planet X or Planet Nine.  University of Hawaii’s Dave Tholen and Northern Arizona University’s Chad Trujillo are also part of the planet search team.

“Jupiter just happened to be in the sky near the search fields where we were looking for extremely distant Solar System objects, so we were serendipitously able to look for new moons around Jupiter while at the same time looking for planets at the fringes of our Solar System,” said Sheppard.

Gareth Williams at the International Astronomical Union’s Minor Planet Center used the team’s observations to calculate orbits for the newly found moons. 

“It takes several observations to confirm an object actually orbits around Jupiter,” Williams said. “So, the whole process took a year.”

Nine of the new moons are part of a distant outer swarm of moons that orbit it in the retrograde, or opposite direction of Jupiter’s spin rotation.  These distant retrograde moons are grouped into at least three distinct orbital groupings and are thought to be the remnants of three once-larger parent bodies that broke apart during collisions with asteroids, comets, or other moons. The newly discovered retrograde moons take about two years to orbit Jupiter.

Two of the new discoveries are part of a closer, inner group of moons that orbit in the prograde, or same direction as the planet’s rotation. These inner prograde moons all have similar orbital distances and angles of inclinations around Jupiter and so are thought to also be fragments of a larger moon that was broken apart. These two newly discovered moons take a little less than a year to travel around Jupiter.

 “Our other discovery is a real oddball and has an orbit like no other known Jovian moon,” Sheppard explained. “It’s also likely Jupiter’s smallest known moon, being less than one kilometer in diameter”. 

This new “oddball” moon is more distant and more inclined than the prograde group of moons and takes about one and a half years to orbit Jupiter.  So, unlike the closer-in prograde group of moons, this new oddball prograde moon has an orbit that crosses the outer retrograde moons.

As a result, head-on collisions are much more likely to occur between the “oddball” prograde and the retrograde moons, which are moving in opposite directions. 

“This is an unstable situation,” said Sheppard. “Head-on collisions would quickly break apart and grind the objects down to dust.”

 It’s possible the various orbital moon groupings we see today were formed in the distant past through this exact mechanism.

The team think this small “oddball” prograde moon could be the last-remaining remnant of a once-larger prograde-orbiting moon that formed some of the retrograde moon groupings during past head-on collisions.  The name Valetudo has been proposed for it, after the Roman god Jupiter’s great-granddaughter, the goddess of health and hygiene.

Elucidating the complex influences that shaped a moon’s orbital history can teach scientists about our Solar System’s early years. 

For example, the discovery that the smallest moons in Jupiter’s various orbital groups are still abundant suggests the collisions that created them occurred after the era of planet formation, when the Sun was still surrounded by a rotating disk of gas and dust from which the planets were born.

Because of their sizes—one to three kilometers—these moons are more influenced by surrounding gas and dust. If these raw materials had still been present when Jupiter’s first generation of moons collided to form its current clustered groupings of moons, the drag exerted by any remaining gas and dust on the smaller moons would have been sufficient to cause them to spiral inwards toward Jupiter. Their existence shows that they were likely formed after this gas and dust dissipated.

The initial discovery of most of the new moons were made on the Blanco 4-meter telescope at Cerro Tololo Inter-American in Chile and operated by the National Optical Astronomical Observatory of the United States.  The telescope recently was upgraded with the Dark Energy Camera, making it a powerful tool for surveying the night sky for faint objects.  Several telescopes were used to confirm the finds, including the 6.5-meter Magellan telescope at Carnegie’s Las Campanas Observatory in Chile; the 4-meter Discovery Channel Telescope at Lowell Observatory Arizona (thanks to Audrey Thirouin, Nick Moskovitz and Maxime Devogele); the 8-meter Subaru Telescope and the Univserity of Hawaii 2.2 meter telescope (thanks to Dave Tholen and Dora Fohring at the University of Hawaii); and 8-meter Gemini Telescope in Hawaii (thanks to Director’s Discretionary Time to recover Valetudo).  Bob Jacobson and Marina Brozovic at NASA’s Jet Propulsion Laboratory confirmed the calculated orbit of the unusual oddball moon in 2017 in order to double check its location prediction during the 2018 recovery observations in order to make sure the new interesting moon was not lost.

https://carnegiescience.edu/node/2367

Diamonds In Earth's Mantle

Sound Waves Reveal Diamond
Cache Deep in Earth’s Interior
Study finds 1–2 percent of Earth’s oldest mantle rocks are made from diamond
By Jennifer Chu | MIT News Office

July 16, 2018 -- There may be more than a quadrillion tons of diamond hidden in the Earth’s interior, according to a new study from MIT and other universities. But the new results are unlikely to set off a diamond rush. The scientists estimate the precious minerals are buried more than 100 miles below the surface, far deeper than any drilling expedition has ever reached.

The ultradeep cache may be scattered within cratonic roots — the oldest and most immovable sections of rock that lie beneath the center of most continental tectonic plates. Shaped like inverted mountains, cratons can stretch as deep as 200 miles through the Earth’s crust and into its mantle; geologists refer to their deepest sections as “roots.”

In the new study, scientists estimate that cratonic roots may contain 1 to 2 percent diamond. Considering the total volume of cratonic roots in the Earth, the team figures that about a quadrillion (10¹⁶) tons of diamond are scattered within these ancient rocks, 90 to 150 miles below the surface.   

“This shows that diamond is not perhaps this exotic mineral, but on the [geological] scale of things, it’s relatively common,” says Ulrich Faul, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences. “We can’t get at them, but still, there is much more diamond there than we have ever thought before.”

Faul’s co-authors include scientists from the University of California at Santa Barbara, the Institut de Physique du Globe de Paris, the University of California at Berkeley, Ecole Polytechnique, the Carnegie Institution of Washington, Harvard University, the University of Science and Technology of China, the University of Bayreuth, the University of Melbourne, and University College London.

A sound glitch

Faul and his colleagues came to their conclusion after puzzling over an anomaly in seismic data. For the past few decades, agencies such as the United States Geological Survey have kept global records of seismic activity — essentially, sound waves traveling through the Earth that are triggered by earthquakes, tsunamis, explosions, and other ground-shaking sources. Seismic receivers around the world pick up sound waves from such sources, at various speeds and intensities, which seismologists can use to determine where, for example, an earthquake originated.

Scientists can also use this seismic data to construct an image of what the Earth’s interior might look like. Sound waves move at various speeds through the Earth, depending on the temperature, density, and composition of the rocks through which they travel. Scientists have used this relationship between seismic velocity and rock composition to estimate the types of rocks that make up the Earth’s crust and parts of the upper mantle, also known as the lithosphere.

However, in using seismic data to map the Earth’s interior, scientists have been unable to explain a curious anomaly: Sound waves tend to speed up significantly when passing through the roots of ancient cratons. Cratons are known to be colder and less dense than the surrounding mantle, which would in turn yield slightly faster sound waves, but not quite as fast as what has been measured.   

“The velocities that are measured are faster than what we think we can reproduce with reasonable assumptions about what is there,” Faul says. “Then we have to say, ‘There is a problem.’ That’s how this project started.”

Diamonds in the deep

The team aimed to identify the composition of cratonic roots that might explain the spikes in seismic speeds. To do this, seismologists on the team first used seismic data from the USGS and other sources to generate a three-dimensional model of the velocities of seismic waves traveling through the Earth’s major cratons.

Next, Faul and others, who in the past have measured sound speeds through many different types of minerals in the laboratory, used this knowledge to assemble virtual rocks, made from various combinations of minerals. Then the team calculated how fast sound waves would travel through each virtual rock, and found only one type of rock that produced the same velocities as what the seismologists measured: one that contains 1 to 2 percent diamond, in addition to peridotite (the predominant rock type of the Earth’s upper mantle) and minor amounts of eclogite (representing subducted oceanic crust). This scenario represents at least 1,000 times more diamond than people had previously expected.

“Diamond in many ways is special,” Faul says. “One of its special properties is, the sound velocity in diamond is more than twice as fast as in the dominant mineral in upper mantle rocks, olivine.”

The researchers found that a rock composition of 1 to 2 percent diamond would be just enough to produce the higher sound velocities that the seismologists measured. This small fraction of diamond would also not change the overall density of a craton, which is naturally less dense than the surrounding mantle.

“They are like pieces of wood, floating on water,” Faul says. “Cratons are a tiny bit less dense than their surroundings, so they don’t get subducted back into the Earth but stay floating on the surface. This is how they preserve the oldest rocks. So we found that you just need 1 to 2 percent diamond for cratons to be stable and not sink.”

In a way, Faul says cratonic roots made partly of diamond makes sense. Diamonds are forged in the high-pressure, high-temperature environment of the deep Earth and only make it close to the surface through volcanic eruptions that occur every few tens of millions of years. These eruptions carve out geologic “pipes” made of a type of rock called kimberlite (named after the town of Kimberley, South Africa, where the first diamonds in this type of rock were found). Diamond, along with magma from deep in the Earth, can spew out through kimberlite pipes, onto the surface of the Earth.

For the most part, kimberlite pipes have been found at the edges of cratonic roots, such as in certain parts of Canada, Siberia, Australia, and South Africa. It would make sense, then, that cratonic roots should contain some diamond in their makeup.  

“It’s circumstantial evidence, but we’ve pieced it all together,” Faul says. “We went through all the different possibilities, from every angle, and this is the only one that’s left as a reasonable explanation.”

This research was supported, in part, by the National Science Foundation.

             http://news.mit.edu/2018/sound-waves-reveal-diamond-cache-deep-earths-interior-0716

Comet Shoemaker-Levy 9

Comet Shoemaker–Levy 9 (formally designated D/1993 F2) was a comet that broke apart in July 1992 and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its possible role in reducing space debris in the inner Solar System.

The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy in 1993. Shoemaker–Levy 9 had been captured by Jupiter and was orbiting the planet at the time. It was located on the night of March 24 in a photograph taken with the 46 cm (18 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by Jupiter around 20–30 years earlier.

Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull apart the comet. The comet was later observed as a series of fragments ranging up to 2 km (1.2 mi) in diameter. These fragments collided with Jupiter's southern hemisphere between July 16 and 22, 1994 at a speed of approximately 60 km/s (37 mi/s) (Jupiter's escape velocity) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.

Impacts of the Comet Fragments

Anticipation grew as the predicted date for the collisions approached, and astronomers trained terrestrial telescopes on Jupiter. Several space observatories did the same, including the Hubble Space Telescope, the ROSAT X-ray-observing satellite, and significantly the Galileo spacecraft, then on its way to a rendezvous with Jupiter scheduled for 1995. Although the impacts took place on the side of Jupiter hidden from Earth, Galileo, then at a distance of 1.6 AU (240 million km; 150 million mi) from the planet, was able to see the impacts as they occurred. Jupiter's rapid rotation brought the impact sites into view for terrestrial observers a few minutes after the collisions.

Two other satellites made observations at the time of the impact: the Ulysses spacecraft, primarily designed for solar observations, was pointed towards Jupiter from its location 2.6 AU (390 million km; 240 million mi) away, and the distant Voyager 2 probe, some 44 AU (6.6 billion kilometres; 4.1 billion miles) from Jupiter and on its way out of the Solar System following its encounter with Neptune in 1989, was programmed to look for radio emission in the 1–390 kHz range.

The first impact occurred at 20:13 UTC on July 16, 1994, when fragment A of the nucleus entered Jupiter's southern hemisphere at a speed of about 60 km/s (35 mi/s). Instruments on Galileo detected a fireball that reached a peak temperature of about 24,000 K (23,700 °C; 42,700 °F), compared to the typical Jovian cloudtop temperature of about 130 K (−143 °C; −226 °F), before expanding and cooling rapidly to about 1,500 K (1,230 °C; 2,240 °F) after 40 seconds. The plume from the fireball quickly reached a height of over 3,000 km (1,900 mi). A few minutes after the impact fireball was detected, Galileo measured renewed heating, probably due to ejected material falling back onto the planet. Earth-based observers detected the fireball rising over the limb of the planet shortly after the initial impact.

Despite published predictions, astronomers had not expected to see the fireballs from the impacts and did not have any idea in advance how visible the other atmospheric effects of the impacts would be from Earth. Observers soon saw a huge dark spot after the first impact. The spot was visible even in very small telescopes, and was about 6,000 km (3,700 mi) (one Earth radius) across. This and subsequent dark spots were thought to have been caused by debris from the impacts, and were markedly asymmetric, forming crescent shapes in front of the direction of impact.

Over the next six days, 21 distinct impacts were observed, with the largest coming on July 18 at 07:33 UTC when fragment G struck Jupiter. This impact created a giant dark spot over 12,000 km (7,500 mi) across, and was estimated to have released an energy equivalent to 6,000,000 megatons of TNT (600 times the world's nuclear arsenal). Two impacts 12 hours apart on July 19 created impact marks of similar size to that caused by fragment G, and impacts continued until July 22, when fragment W struck the planet.

https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9

Multigrain Bread

Multigrain bread is a type of bread prepared with two or more types of grain. Grains used include barley, flax, millet, oats, wheat, and whole-wheat flour, among others. Some varieties include edible seeds in their preparation, such as flaxseed, quinoa, pumpkin seeds, and sunflower seeds. Rye and sourdough multigrain breads are additional varieties. Preparations include 7-grain and 9-grain bread, among others.

Multigrain bread may be prepared using whole, unprocessed grains, although commercial varieties do not necessarily always contain whole grains.

Nutritional Content

Whole grain multigrain breads contain a dietary fibre content of up to four times greater than white breads and may also contain more vitamins and protein compared to white bread. Multigrain breads also provide complex carbohydrates.

Commercial Varieties

Multigrain bread is commercially mass-produced and marketed to consumers. Some commercial varieties are prepared using 100% whole grain flour. Between 1989 and 1994 in the United States, multigrain bread was "one of the fastest growing markets within the bakery sector”.

Use in Brewing

A 4,000-year-old Mesopotamian recipe for brewing beer from multigrain loaves of bread mixed with honey is the oldest surviving beer recipe in the world. The Brussels Beer Project microbrewery in Belgium has developed an amber beer with a 7% alcohol by volume named Babylone that incorporates this recipe using leftover, unsold fresh bread donated by supermarkets.

https://en.wikipedia.org/wiki/Multigrain_bread

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Sprouted Bread

Sprouted bread is a type of bread made from whole grains that have been allowed to sprout, that is, to germinate, before being milled into flour. There are a few different types of sprouted grain bread. Some are made with additional added flour, some are made with added gluten, and some, such as Essene bread, are made with very few additional ingredients.

These are breads that contain the whole grain (or kernel, or berry) of various seeds after they have been sprouted. They are different from 'white' bread inasmuch as 'white' breads are made from ground wheat endosperm (after removal of the bran and germ). Whole grain breads include the bran, germ and endosperm, therefore providing more fiber, and naturally occurring vitamins and proteins. Sprouted (or germinated) grain breads have roughly the same amount of vitamins per gram.

A comparison of nutritional analyses shows that sprouted grains contain about 75% of the energy (carbohydrates), slightly higher protein and about 40% of the fat when compared to whole grains.

Wheat is not the only grain used in sprouted breads. Grains and legumes such as millet, barley, oat, lentil and soy may be used. Bread that is made from an array of grains and legumes can provide a complete set of amino acids, the building blocks of proteins. Sprouted breads may contain slightly more trace minerals and nutrients than non-sprouted breads. Other than that, they supply much the same advantages as whole grain breads over refined grain breads, such as lowered risk of coronary heart disease.

https://en.wikipedia.org/wiki/Sprouted_bread#Essene_bread

Earliest Hominins Outside Africa

Shangchen is a palaeolithic archaeological site in Shangchen village, Lantian County, Shaanxi, China. Stone tools found at the site and dated to 2.12 million years ago, now are considered the earliest known evidence of hominins outside Africa, surpassing Dmanisi in Georgia by 300,000 years. Shangchen was occupied for 850,000 years, with the newest tools found dating to 1.26 million years ago. No hominin fossils have been found.

Location

Shangchen is located in and named after the village of Shangchen, Yushan Town, Lantian County, Shaanxi, about 50 km (31 mi) southeast of the provincial capital at Xi'an. The archaeological site is on the cliff faces of a gully in the Loess Plateau. Because loess is a soil made by extremely fine particles blown in by the wind, all larger rocks found in loess deposits had to have been carried in by humans or other animals.

Discovery and Excavation

Lantian County is where fossils of the Homo erectus, now called Lantian Man, were discovered in 1964. The oldest fossil, a skull, was initially dated to 1.15 million years ago. In 2001, geologist Zhu Zhaoyu and other scientists began researching the site again, and determined that the skull was 1.63 million years old.

Zhu's team surveyed the region around the fossil site, and discovered stone tools buried deep in the side of a gully in Shangchen, less than three miles away. The team, later joined by British paleoanthropologist Robin Dennell in 2010, thoroughly searched the gully and excavated the site between 2004 and 2017, and their findings were published in July 2018 in the journal Nature.

Findings at Shangchen

96 stone tools have been found at Shangchen, including flakes, points, and cores. They were found in 17 artifact layers. The oldest of the tools date to 2.12 million years ago, while the newest date to 1.26 million years, indicating that the site was occupied (not necessarily continuously) for 850,000 years. Some of the tools were found with bone fragments of animals including deer and bovines. Even older remains may still lie undiscovered, as the deepest layers at Shangchen are inaccessible as of 2018 because of farming activities.

The findings are highly significant as they represent the earliest evidence of hominins outside Africa, surpassing Dmanisi in the Caucasus region of Georgia, which was the previously known oldest hominin site outside Africa, dating to 1.85 million years ago. It is also older than the Yuanmou Man, the oldest hominin fossils found in East Asia, dating to 1.7 million years.

https://en.wikipedia.org/wiki/Shangchen

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Footnote: The Paleolithic Period

The Paleolithic or Palaeolithic is a period in human prehistory distinguished by the original development of stone tools that covers c. 95% of human technological prehistory. It extends from the earliest known use of stone tools by hominins, c. 3.3 million years ago, to the end of the Pleistocene c. 11,650 cal BP.

The Paleolithic is followed in Europe by the Mesolithic, although the date of the transition varies geographically by several thousand years.

During the Paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering plants and fishing, hunting or scavenging wild animals. The Paleolithic is characterized by the use of knapped stone tools, although at the time humans also used wood and bone tools. Other organic commodities were adapted for use as tools, including leather and vegetable fibers; however, due to their nature, these have not been preserved to any great degree.

https://en.wikipedia.org/wiki/Paleolithic