this is bbc news. here are the headlines. president trump has hosted campaigners whose relatives we re hosted campaigners whose relatives were murdered by our document of migrants. it is seen as an effort to regain the initiative from outrage over the separation of migrant families bossing the border with mexico. hundreds of children remain separated despite a change in policy. the united nations human rights council has accused venezuela's security forces geli hundreds of people under the pretext of fighting crime and then taking evidence that might have killed. the un human rights chief has called for an enquiry into the alleged abuses. and on day nine of the world cup, brazil narrowly escaped an embarrassing draw and beat costa rica 2—0. nigeria beat iceland 2—0. that makes it more likely that argentina might be able to buy from group d. now on bbc news it is time

for click. this week — robot hunts killer starfish, hurricane in a tube, and gravity trainer runs out of steam. —— train. florida, america's sunshine state. and home to the us‘s first sustainable town. this is babcock ranch. powerade, but fittingly, almost entirely by that big ball in the sky. —— powered. it is 33

degrees. that unity is, i believe, about i,000,000%. and i degrees. that unity is, i believe, abouti,000,000%. and i have degrees. that unity is, i believe, about i,000,000%. and i have come to about i,000,000%. and i have come to a solar field, so you don't have too —— humidity. 343,000 solar panel spent some 440 acres, providing 75 megawatts of electricity. that is enough to power 15,000 homes. 0ne megawatts of electricity. that is enough to power 15,000 homes. one of the big things with solar energy has been with the clouds, over or especially when it gets dark, the whole thing effectively goes dead. and we have not really had a way of storing solar energy until very recently. but over there, ten buildings full of batteries. so it isa buildings full of batteries. so it is a start. a pretty good one, too. babcock has the largest combined solar and storage facility in the us. the batteries can store 40 megawatt hour of electricity, which is enough to keep around 2000

average us homes are light for four hours. of course, lithium batteries arejust one way hours. of course, lithium batteries are just one way of storing energy to use later. we have seen other methods before. there is electric mountain in wales which holds water ata mountain in wales which holds water at a top reservoir until power is needed, it then releases it back down to the lake below. switzerland's air kei fills itself with compressed air and then blows it out to turn turbines —— k yukka. now, over in california, kate russell is on track to see a new solution. since the oil crisis of the 1970s, california has invested heavily into wind and solar power, with the latest state legislation calling for 50% renewable energy by 2030 and all new homes must have solar within two years. the state is a way ahead of its target, so much so a way ahead of its target, so much so that they have had to start paying neighbouring states to take some of the energy from them. as

we've heard before, the problem is storage will stop the grid was built to handle fossil fuel generated power and storage solutions like hydroelectric dams are in short supply. batteries are bad for the environment, turning a news renewable energy into not such a green solution. california —based company aries have come up with one alternative. aries was really an attempt to think of a way to use the inexhaustible, always reliable power of gravity. we know gravity is going to be there for us. we don't have to worry about shortages or any of that. so how do we use gravity to store and then discharge power when we needed? one of the most official ways that make best ways to use than israel waves. 150 years of experience, incredibly efficient, steel wheels on steel rails are one

of the most efficient ways to move mass. dubbed the gravity train, energy is used in electricity to push its weight uphill. when you wa nt to ta ke push its weight uphill. when you want to take the energy out you let gravity pull the train backed down, using the friction braking too slow to be trained in order to make power. it was like the sameway hybrid electric cars like previous work. you see those wind turbines behind me, they are completely still, even though there is clearly plenty of wind right now. it is not because they are broken, it is because they are broken, it is because there is no more room to store the energy they would create. and that is the problem the gravity train well sold. when you are into access energy production, use it to power the train up a hill, when you wa nt power the train up a hill, when you want the energy back, centre the train backed down again. this demo train backed down again. this demo train carries almost five times uphill, is touring energy as it goes. a full—scale installation will

return 80% of the stored energy, which is not quite as efficient as a huge dam, but has a lot less impact. the amount of energy we store is the weight of the train times the height of the hill. the more weight and the high the hill be more energy we can store. we need long, gently sloping plains. we have clients who approached us and said i only have steep, rocky, craggy mountains, so we have developed a new variation on the aries technology at almost vertical. in october, the company brea ks vertical. in october, the company breaks ground on the first full—scale aries in the state of nevada. it will be used to fine tune the inconsistent energy flows that area the inconsistent energy flows that are a natural part of using solar and wind power. minute by minute it will trim the imbalance between the load and generation on the grid, so oui’ load and generation on the grid, so our trains may need to go uphill for a minute, they need to go downhill

for five minutes, they a minute, they need to go downhill forfive minutes, they are co nsta ntly forfive minutes, they are constantly acting like a large flywheel that allows the grid to stay at exactly 60 hertz. it is early days yet and the concept has yet to be proved in nevada, but it could help solve one of the renewable industries biggest conundrum is right now, balancing the ebb and flow of nature made enemy in a more substantial way circular after we run 30 or 40 years providing energy storage and helping people we can remove all of our facilities very quickly, 96% of them can be either repurposed or recycled, so only 4% of our facilities would ever go into a landfill. we are trying to reduce that. we can then played some native vegetation and six months later you would never know our facility was there. —— plant. would never know our facility was there. -- plant. that was kate on a roll in california. back at babcock iam going roll in california. back at babcock i am going for a solar powered speed

in an autonomous shuttle, with its chief financial officer. i guess the motivation for having these autonomous vehicles is that you are encouraging families here to not have as many cars. correct. our thought is that over time most families in the us are a two car family. our hope is that we can get from a two carp to a 1—carfamily, you have a couple of the family, perhaps, but if you have it for a commuterfor work you perhaps, but if you have it for a commuter for work you were needed, you can take the autonomous shuttle to work. 0ver you can take the autonomous shuttle to work. over time perhaps there are no cars will stop i think, realistically, within the next 10— 15 years we can go from two to 1—car. 15 years we can go from two to 1-car. you think the us government at the moment doesn't...” 1-car. you think the us government at the moment doesn't. .. i think they get it. governments move slowly, typically. in major cities, major metros, where traffic and pollution are an issue, technology can come in and save a lot of that. i think governments can step up and sold a lot of that. we are seeing that slowly. what we are hearing and reading about it a lot of major

urban cores are going to become, there will be restricted access, if you drive your car train to get the weight gajion, up to a certain mile, three miles outside of the citicorp you will not be able to get in outside of a autonomous vehicle. building a city or a town that is sustainable, you are not going to be able to do this in colder, more crowded parts of the world. able to do this in colder, more crowded parts of the worldlj able to do this in colder, more crowded parts of the world. i think thatis crowded parts of the world. i think that is right. we have a unique situation here, we have the benefit of scale. there are not many people who have 1000 acres of land. that is a big chunk of it. along with autonomous shuttle is, babcock as is and waste facilities, and as and as well as reclaiming water, there is a restriction on the amount you are allowed to use. the ken rees reflect heat, making homes 10% better at keeping cool, and the range's on—site gym is environmentally friendly, too, it is powered by the treadmills. 0ne incentive to get off

the couch, i suppose. it is a commendable vision to build a town with all these sustainable values, but i can't help thinking can only really do this when you are building a community from scratch. i mean, could you imagine trying to retrofit an existing town with all of these technologies? you basically have two terror the infrastructure and tear down all the buildings and start from scratch anyway —— how daredevil stock babcock has been built in the style of old towel —— out, to attract those who are not necessarily find a venue built feel. are you expecting the? people like the kinleys. dumai tavai step inside your air—conditioning and stay there. they have a robot vacuum cleaner —— do you mind if i. there. they have a robot vacuum cleaner -- do you mind if i. a copy making fridge. it is set up so it won't spill all over the place. and an electric car. for richard, a self—confessed geek and a real fan of click, babcock was his calling.

just reading tech blogs all the time on the internet and it sounded fascinating to me. i liked the idea that it was an environmentally friendly and was looking forward as faras energy friendly and was looking forward as far as energy solutions. in atlanta, we lived just aung win from one of the biggest coal polluting pout —— plants in the country. i thought that cannot be healthy. plants in the country. i thought that cannot be healthylj plants in the country. i thought that cannot be healthy. i think of it as guilt free living. in the uk when you have a small town with a central area and you can walk to, it encourages walking, so it is the lifestyle. and while the buildings may look like historic florida, for me it was also all the technology, you know, having1 me it was also all the technology, you know, having 1 gigabyte of fibre optic, intranet in the homes... yeah, you definitely like that. hello and welcome to the week in

tech. it was the week that the world health organization classified gaming disorder as a condition capable of causing debilitating addiction. arguing with your malfunctioning tech could soon become a whole lot more intellectually stimulating. ibm put it is project abated to its test this week. the system as the arguments of its human opponent and then scans hundreds of millions of documents in its memory to construct what it considers to be a sound and logical argument. having analysed the data, i will argue... logical argument. having analysed the data, iwill argue... ever logical argument. having analysed the data, i will argue... ever wish you got something can slow motion r0 filmed at? a chip designer shows us how ai could be used to fill in the gaps, turning 30 frames per second footage into 240 frames per second slick slow motion. and finally, the battle for our eyes and ears is hotting up. facebook has gone head

to head with youtube, with plans to let social media stars into its previously high end watch programme. meanwhile, facebook owned instagram is has plans to host longer videos on the programme, much like youtube. youtube has been wanting its subscription service, making content available off—line in 12 more countries, including the uk. confused? just go watch a video and relax. hurricane season is just around the corner in the us and that means that south florida is once again at risk from deadly winds and storm surges. much of it lies less than five metres above sea level. miami airport isjust one metres above sea level. miami airport is just one meat. metres above sea level. miami airport isjust one meat. and in the further future, even airport isjust one meat. and in the furtherfuture, even moderate estimates of climate change mean that the sea will follow much of this area by the year 2100. it is

probably no surprise that some of the most advanced hurricane research in the world is going on here at the university of miami. this is a hurricane simulator. it is a23 this is a hurricane simulator. it is a 23 metre long glass tank filled with water and connected to an enormous fan, which means they can generate the strongest winds overwater anywhere in the world. up there they can simulate a category 5 hurricane. a 1500 horsepower motor drives 65 metre per second winds, flipping up spray and smashing waves into whatever they put in the tank. the sensors in the tank measure how those waves behave and what they do to florida's buildings. because it

is not so much the winds as the storm surge. the water driven inland by the storm that causes so much destruction and loss of life. in a hurricane, two metres of floodwater is accompanied with large waves on top of that and the way bleeding is really dramatic. it is what we are talking about, with waves that are quite often breaking and coming and hitting the structure. it is an impulsive force but it is repeated, many times, during a storm. even if it is only an hour, that can really do dramatic damage. and what have you found so far? how can you build houses better now because of what you have found ? houses better now because of what you have found? one of the key things we have found in some recent measurements related to the structures directly, is that often, with decking, it is actually where the wave gets trapped underneath it. that is like an explosive uplift force. so you really have to look at how you engineer the attachments on

things. 0k, we are about to go to full speed. 0k, 0k, we are about to go to full speed. ok, here comes the spray now. understanding the forces on these models will help develop new guidelines on what support structures would help a building withstand the onslaught of a storm surge. so if somehow you were under the sea during a harry kane, this is where you would see. —— hurricane, this is what you would see. it is better than being on top, i can tell you that. have you ever been there when it is on category five, even in your christmas parties? no, we would not go in there, because there is not go in there, because there is not much to hold on to and in the

back of it is is like cheese slicer. soi back of it is is like cheese slicer. so i don't really want to be turned into sausage or cheese. the team here aren't just trying into sausage or cheese. the team here aren'tjust trying to make stronger buildings. they are also testing ways of stopping the full force of the waves from getting to the land in the first place. here, they are looking at the effect of they are looking at the effect of the seawall on protecting the house. further out in the water, something you might not expect. a coral reef. we've actually been reading some global studies which show that wave energies actually dissipated 97% on average, as waves hit a reef crest, and go towards shore. so they act like 97% efficient waves break? that's right, it is a healthy reef with a reef crest. it doesn't look to me like there is that much coral there. and it doesn't come to the surface. does that really do a good job? it can, actually, yes. with the

waves you have the kind of circular motion that happens at the top, it causes circular motion all the way down, ina causes circular motion all the way down, in a little... come down to the seafloor. —— little ellipsis. anything that disrupts that helps to slow down the wave. the problem is that just when we slow down the wave. the problem is thatjust when we need coral to protect from climate change, climate change is killing coral. although corals, much like the trees in the ra i nfo rest, corals, much like the trees in the ra i nforest, a re corals, much like the trees in the rainforest, are the possible habitat builders of the ecosystem, it you lose the corals, just like if you lose the corals, just like if you lose the corals, just like if you lose the trees in the rainforest, you end up with no ecosystem. the corals building that habitat are very thermally sensitive. they are some of the most climate change sensitive species on the planet. the reason they are so sensitive to climate change is because they are very vulnerable to small changes in temperature. an unusually hot summer causes a coral to turn white, in a process we call coral bleaching. that sets of tony white is a process whereby this symbiosis between the

coral animal and this tiny single cell plant that lives inside its tissue, that's an biosis breaks down and the coral spits out its allergy, turns white, and unless it can somehow turns white, and unless it can somehow recover turns white, and unless it can somehow recover those allergy it will die. it starves, from lack of food. andrew baker has spent the last 25 years trying to create coral thatis last 25 years trying to create coral that is more resistant to increasing temperatures. we have found over the yea rs temperatures. we have found over the years that lie gently bleaching corals deliberately in the laboratory we can encourage them to change their sin by its in favour of this thermally tolerant types. —— change their symbiotes. just now we are starting for the first time this pilot experiment of doing this out in nature, in the field, in reefs off miami, where it is what we are calling stress hardening these corals, encouraging them to change their algae in favour of the tolera nt their algae in favour of the tolerant ones that will help them to resist bleaching and hopefully persist into the future. so

beautiful, isn't it? and while they are working towards growing more resilient coral here in miami, there are of course projects going on across the globe to protect the coral we already have stopped next kwek coral we already have stopped next kwe k we nt coral we already have stopped next kwek went to see one such project at the most banal —— famous coral reef in the world. the great barrier reef, australia, wonder of the world. earth's largest living thing, sprawling 1600 miles. but this paradise could soon be lost at the hands of a very surprising vandal. crown of thorns starfish eat coral, and although they are found he naturally, recently too many have been pouring in at once due to major weather events and ocean pollution. you would think a starfish would be a cute, gorgeous thing you would see on the great barrier reef. the crown of thorns starfish, not so much. they are spiky, ugly, they can have up they are spiky, ugly, they can have up to 20 or 30 arms. the biggest

issue with crown of thorns starfish issue with crown of thorns starfish is that they can eat up to one metre of coral per day. when they are in plague proportions they can absolutely desolate a reef. to the rescue, the range of bots. —— ranger bots. these underwater drones autonomously scoured the reef starfish and prick them with a deadly dose of salt. the bots use an algorithm to identify starfish and then target them. they are developers say they are not in 9.4% accurate. and they get smarter with time. traditionally, divers have monitored the reef by going out and doing a visual check. they record their findings doing a visual check. they record theirfindings on a doing a visual check. they record their findings on a slate. something time can assuming, not to mention expensive. —— time—consuming. time can assuming, not to mention expensive. -- time-consuming. they can only be in the water for up to three orfour can only be in the water for up to three or four macalister day. they can't dive at night. whereas the

ranger bot has the capacity to be in the water for ranger bot has the capacity to be in the waterfor eight ranger bot has the capacity to be in the water for eight hours a day. it can dive at night. it also doesn't have some of the human failings that we know we have, where reaction we see and miss things as we are getting dragged along under the water. working around the clock could make a big difference to. evidence suggests the thorny carnivores come out more at night. the ranger bots of lights, so their cameras can still see once the sun goes down. so inside these things you have got inertial sensors, pressure sensors, a gps so it knows where it is going. and it also has to make computers working some of tony asleep. 0ne to make computers working some of tony asleep. one to process the images and want to know where it is going and understand the navigation route. the game changer is that b6 thrusters, which allow it to go forward , thrusters, which allow it to go forward, backwards, up, down, left and right, it also side to side, so when it spots the crown of thorns starfish it doesn't need to do a big loop the loop, it can just stop and zap them where they are. the bots

are team players, too. the beauty of having this is that if we have multiple vehicles we put them here, we send them off in all directions, they pop up 500 metres away and they already know how many they have seen. already know how many they have seen. so we say, ok, zero, zero, zero, ten. that is our focus area. within 20 minutes we know roughly where we should be focusing our efforts. we will never outcompete a human and we are not trying to outcompete a human, but if we can give them the tools to extend their operational capability, that is a goal. constantly patrolling the reef, the rangers can also monitor what equality, measure coral bleaching and map the deep blue like never before. —— water quality. bleaching and map the deep blue like never before. -- water quality. one of the issues we have about the great barrier reef is that it is so big we only know a fraction of what is going on under the water. without that information it makes it difficult for marine park managers to have a mature understanding of what is going on, and where they

need to direct that time, management, resources and people. but they are still weather dependent. too strong a current, and the paul little ranger can be thrown violently off course. for all their ingenuity, isn't the relatively small work being done by these bots just a drop in the ocean? the great barrier reef is facing many threats. there isn't going to be a silver bullet solution. but the ranger bot is just bullet solution. but the ranger bot isjust one step bullet solution. but the ranger bot is just one step in that part we can ta ke is just one step in that part we can take in terms of trying to make sure that we can look after the great barrier reef on a local level while the world gets its act together on climate change. that was nick in queensland. that is all from our sustainability special from babcock ranch here in florida. we are staying in the united states for another week. next week we fly up to boston, home of mit, which always offers up 20 very, very cool

innovations. looking forward to that. in the meantime, we live on twitter. thank you for watching, and we will see you soon. hello. talk of a heatwave, i'm pretty sure, will be met with cheers and groans in equal measure. that's next week. the warming of our weather gathers pace this weekend. cloudier skies for some on saturday compared with friday. not all of us are going to be dry, as i will show you in a moment. it is high pressure, settling, drying weather which is building across the uk, you can see the warmer colours moving in as well. the temperatures had up as a further into next week, as we will see in a moment. that said, early risers saturday morning, there will be a chill around.

temperatures quite widely into single figures, overnight averages will be heading up as well. as we look at the picture into saturday, cloud around for northern scotland, there will be some outbreaks of rain, especially into the northern isles and quite breezy here compared with elsewhere. elsewhere, light winds and extensive high cloud. the sun will be hazier that it has been. the winds are very light, but quite breezy with the cloud and outbreaks of rain in northern scotland. hazy sunshine though. clearer skies across southern parts. temperatures heading up a few degrees you. elsewhere, many not too much of a difference yet. more of a difference on sunday. the rain will clear away for much of northern scotland in three saturday evening and night. a bit early sunday into shetland. elsewhere, under clear skies, temperatures dip, but again maybe not quite as far as they have been doing. more places holding up into double figures. on sunday, high pressure plonked is right across the british isles. the weather fronts being steered well to the north. early rain in shetland will clear away. for most, there will hardly be a cloud in the sky.

a little hazy in places, particularly across southern parts, out through some eastern areas of england. patchy cloud in north—west scotland. they are the exceptions to an otherwise glorious part two of the weekend. the warmth begins to gather pace. more of us into the low 20s on sunday. bit of cloud towards north—west scotland on monday. elsewhere, plenty of sunshine. the temperatures go up further, low to mid 20s on monday. it is widely into the mid—20s and maybe upper 20s as well as we look beyond that. the hotspots getting new 30 celsius for the first time this year. it will be a bit cooler on the coast. remember the overnight temperatures warming up a bit as well. high uv and very high pollen levels in places. it looks likely we will make 30 celsius at some stage next week. welcome to bbc news,

broadcasting to viewers in north america on pbs and around the globe. my name is ben bland. our top stories: president trump tries to regain control of the fight over immigration, meeting victims of crime at the white house. and mr trump threatens to impose import duties of 20% on european cars — the latest stage in the trans—atlantic trade war. the un's human rights council says venezuela's security forces have killed hundreds under the pretext of fighting crime. and italy says malta has refused to take in 200 migrants currently on board a mediterranean rescue ship.