hello, i'm ben. this is bbc news. the headlines: the approach of hurricane lane is causing flash flooding and landslides in parts of hawaii. more than 2,000 people have taken shelter in evacuation centres, others have been stocking up on water and food. in the past hour, it's has been downgraded to a category one hurricane. —— storm. president trump has cancelled next week's planned trip to north korea by his secretary of state. in tweets, mr trump complained that not enough progress had been made in dismantling pyongyang's nuclear programme. he blamed china for the stalled process — suggesting a link with current trade tensions. pope francis is due to arrive in ireland for the first papal visit there in four decades. the centrepiece of the visit will be a mass on sunday in front of 0.5 million people. a series of scandals has damaged the reputation of the catholic church in recent years. now here on bbc news, it's time for click. this week, another chance to see our

sustainability special from june, featuring robots hunting killer starfish. the hurricane in a tube and a gravity trains. —— train. florida, america's sunshine state. and home to the us‘s first sustainable town. this is babcock ranch. powered, befittingly, almost entirely by that big burning ball in the sky. it's 33 degrees.

the humidity is, i believe, about i,000,000%. and i've come to a solar field, so you don't have to. 343,000 solar panels span some 440 acres, providing 75 megawatts of electricity. and that's enough to power 15,000 homes. one of the big problems with solar energy has been when the clouds come over or especially when it gets dark, the whole thing effectively goes dead. and we haven't really had a way of storing solar energy until very recently. but over there, ten buildings full of batteries. so it's 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 hours of electricity, which is enough to keep around 2000 average us homes alight forfour hours. of course, lithium batteries are just one way of storing energy to use later.

and we've seen other methods before. there's electric 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 cave fills itself with compressed air and then blows it out to turn turbines. 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 way ahead of its target, so much so that they've had to start paying neighbouring states to take some of the energy from them. as we've heard before, the problem is storage. the grid was built to handle fossil

fuel generated power and storage solutions like hydroelectric dams are in short supply. batteries, too, are very bad for the environment, turning unused 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. right? 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 need it? one of the most efficient ways to move mass known to man, which people have spent billions of dollars to perfect, are railroads. right? 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 stored using electricity to push its weight uphill.

when you want to take the energy out, you let gravity pull the train back down, using the friction of braking to slow the train in order to make power. it's the same way hybrid electric cars like the prius work. you see those wind turbines behind me, they're completely still, even though there is clearly plenty of wind right now. it's not because they're broken, it's because there's no more room to store the energy they would create. and that's a problem the gravity train will solve. when you're into excess energy production, use it to power the train up a hill, and when you want the energy back, you just send the train back down again. this demo train carries almost five tonnes uphill, storing 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. simple mathematics. so the more weight and the higher the hill, the more energy we can store. we need long, gently sloping plains. but we had clients who approached us and said well, i only have steep, rocky, craggy mountains, so we've developed a new variation on the aries technology at almost vertical. in october, the company breaks ground on the first full—scale aries in the state of nevada. it'll be used to fine tune the inconsistent energy flows that are a natural part of using solar and wind power. minute by minute, it will trim the imbalance between load and generation on the grid, so our trains may need to go uphill for a minute, they may need to go downhill forfive minutes, they're constantly acting like a large flywheel,

that allows the grid to stay at exactly 60 hertz. it's early days yet and the concept has still to be proved in nevada, but it could help solve one of the renewable industry's biggest conundrums right now, balancing the ebb and flow of nature—made energy in a more substantial way. —— sustainable way. 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 could ever go into a landfill. and we're trying to reduce that. and we can then plant some native vegetation and six months you never know our facility was there. that was kate on a roll in california. back at babcock, i'm going for a solar—powered spin in an autonomous shuttle, with its chief financial officer. so i guess the motivation for having these autonomous vehicles

is that you — you're encouraging families here to not have as many cars. correct. i think our thought is that over time, most families in the us have a two—car family. our hope is that we can get from a two—car to a one—car family. where you have a car for the family, perhaps, but if you have it a car for a commuter for work, you won't need it anymore, you can take an autonomous shuttle or an autonomous vehicle to work. over time, which will take a long time perhaps, there are no cars. but i think, realistically, within the next 10—15 years, you could see a time when you go from two car to one car. you think the us government at the moment doesn't understand? i think they get it. i think they're getting it. the government's a little slow to move, 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 are willing to step up and make sure this comes to fruition. and we're seeing that slowly. what we're hearing and reading

about is a lot of the major urban cores are going to become, there'll be restricted access, if you're driving your car and you're trying to get there, you can't get there — up to a certain mile, three miles outside of the city core, you can't get into the city core without being in an autonomous vehicle, for instance. but outside of autonomous vehicles, building a city or a town that is sustainable, i mean you're not going to be able to do this in colder, more crowded parts of the world. no, i think that's right. i think this is fairly unique. we have a unique situation here, we have the benefit of scale. there's not a lot people who own 18,000 acres of land. that's a big chunk of dirt. along with autonomous shuttles, babcock has its own water and waste facilities, and as well as reclaiming water, there's a restriction on the amount you're allowed to use. the tin roofs reflect heat, making homes 10% better at keeping cool, and the ranch‘s on—site gym is environmentally friendly too, it's 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 that you 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'd basically have to tear up the infrastructure and tear down all the buildings and start from scratch anyway. babcock has been built in the style of older towns, to attract people who aren't necessarily fans of the new build feel. hi. are you expecting me? people like the kinleys. do you mind if ijust step inside your air—conditioning and stay here forever? yeah, yeah. they've got a robot vacuum cleaner... a coffee making fridge... no, it's set up so it won't spill all over the place. ..and of course, an electric car. for richard, a self—confessed geek and actual 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 environmentally friendly and was looking forward as far as energy solutions. we — in atlanta, we lived just downwind from one of the biggest coal polluting plants in the country, and 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 that you can walk to, it encourages walking, so it's the lifestyle. and while the buildings may look like historic florida, for me it was also all the technology, all the — you know, having1 gigabyte of fibre optic internet to the home... yeah, you like that, you definitely like that. hello and welcome to the week in tech. it was the week that facebook had to

apologise again, this time for deleting content from the far right group. it came as president trump accused tech firms of being biased against the right—wing. with wi—fi and phone signals now widely available on planes, it seems there isa available on planes, it seems there is a last place on earth to get some it tranquillity. —— airplanes. however, it seems researchers found a way to break the barrier. it is hoped that in future the technology could be used to locate missing black box recorders at sea. it was also the week that in colombia authorities began using drones to hunt out illegal fields of the cocaine plant that produces the drug. critics though say the problem

needs political action, not technological solutions. and finally, a video did the rounds on twitter this week of a robot out for what looked like a stroll. tha nkfully what looked like a stroll. thankfully though, rather than being a sign of the robot uprising, it is actually a clip, short film using impressive on the flight computer graphics rendering. i for one, however, welcome a computer—generated overlords. 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 five metres above sea level. miami airport is just one metre. five metres above sea level. miami airport isjust one metre. and in the further future, even airport isjust one metre. and in the furtherfuture, even moderate estimates of climate change will mean the sea will swell in much of this area by the year 2100. so is

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

is not so much the winds as the storm surge, the water driven inland by the storm which causes so much destruction and loss of life. in a land falling hurricane, about two metres high floodwater is accompanied with large waves on top of that, and the wave is really dramatic. that is what we are talking about when waves are breaking and coming and hitting structures, that thing is it is impulsive force that is repeated many times during a storm that is only an hour, that can really do damage. what he found so far? how can you build houses better now because of what you found? one of the key things we've found some recent measurements is that with this decking, it is actually when the wave chops there underneath it. it is like an explosive output at first, so we really have to look at

how we engineer the attachments. ok, 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 hurricane, this is what you would see. it's better than being on top, i can tell you that. have you ever been in there when it's on category five, even in your christmas parties? no, we wouldn't go in there, because there's not much to hold on to and in the back of it it's like cheese slicer. so i don't really want to be turned 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 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 wave break? that's right, if it's a healthy reef with a reef crest. it doesn't look to me like there's 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, in a little ellipsis down to the sea floor. anything that disrupts that helps

to 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 rainforest, are the habitat builders of the ecosystem, it 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's a process whereby this symbiosis between the coral animal and this tiny single cell plants that live inside its tissue, that symbiosis breaks down and the coral spits out its algae,

turns white, and unless it can somehow recover those algaes it will die. it starves, from lack of food. andrew baker has spent the last 25 years trying to create coral that's more resistant to increasing temperatures. we have found over the years that by gently bleaching corals deliberately in the laboratory we can encourage them to change their symbiotes in favour of this thermally tolerant type. 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 tolerant ones that will help them to resist bleaching and hopefully persist into the future. so beautiful, isn't it? and while they're working

towards growing more resilient corals here in miami, there are of course projects going on across the globe to protect the coral we already have. nick kwek went to see one such project at the most famous coral reef in the world. the great barrier reef, australia, wonder of the world. earth's largest living thing, sprawling some 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're found here 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're spiky, ugly, they can have up to 20 or 30 arms. the biggest issue with crown of thorns starfish is that they can eat up to one metre of coral per day. when they're in plague

proportions they can absolutely devastate a reef. to the rescue, the ranger bots. these underwater drones autonomously scour the reef starfish and prick them with a deadly dose of biosalt. the bots use an algorithm to identify starfish and then target them. their developers say they're 99.4% 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 on a slate — something time consuming consuming, not to mention expensive. they can only be in the water for up to three or four hours a day. they can't dive at night. whereas the 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 we see and miss things as we are getting dragged

along under the water. working around the clock could make a big difference too. evidence suggests the thorny carnivores come out more at night. the ranger bots have 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's going. and it also has two computers working simultaneously. one to process the images, and one to know where it is going and understand the navigation route. the game changer is these thrusters, which allow it to go forward, backwards, up, down, leftand 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've 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 water quality, measure coral bleaching and map the deep blue like never before. 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's going on, and where they need to direct their time, management, resources and people.

but they are still weather dependent. too strong a current, and the poor little ranger can be thrown violently off course. for all their ingenuity, isn't the relatively small work being done by these botsjust 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 one step in that path 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're 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 at @bbcclick. thank you for watching,

and we will see you soon. hello. loads of showers around on friday, some really heavy with hail and thunder. also cool right across the board. the cool conditions continue into the weekend and of course for many of us this is a bank holiday weekend. we will see further showers at times but also some sunshine. friday's showers clearing away with this low pressure during the early hours of saturday. a few showers still remaining across northern and western areas, a few pushing into the midlands, there. but with lengthy clear skies, a chilly start to this morning, with temperatures widely in single figures. across scotland and north—east england some sheltered spots could get close to freezing. we start the morning on a chilly note, but largely dry and bright with lots of sunshine. breezy across the north—east.

elsewhere, showers developing here and there, but nowhere near as many as we saw on friday. with slightly lighter winds across the south and the west, despite the fact it will still be quite cool for this time of year, with below—average temperatures, it should feel a little bit better. heading through saturday night, it will be another chilly one. a veil of high cloud pushes in off this weather system. i don't think it will be as cool to start sunday as we were expecting this morning. double—figure values across many areas. this area of low pressure will come hurtling in on sunday. it will spread east throughout the day to bring wet and windy weather. a bit of brightness across the far east for a while, but a cool start. very soon the cloud will thicken up. wet and windy weather spreads to all areas. some of this will be heavy. in western areas, it could be blustery with winds of 40—45mph in the south and the west. it will feel disappointingly cool with all the cloud, wind, and rain. temperatures generally in the mid—to—high teens celsius. 0ur area of low pressure pushes into the near continent,

then for monday it looks like we are into a ridge of high pressure, so a bit quieter. still breezy in the west and north—west, but that will feed in further clouds to england and wales through the afternoon. so a few showers, but for most places, drier and quieter, temperatures ranging from 17 to 21 or 22 degrees in the south—east, so a touch warmer. heading through tuesday, a fine and settled day, with a ridge of high pressure and feeling a little bit warmer with some sunny spells. welcome to bbc news, broadcasting to viewers in north america and around the globe. my name is nkem ifiekja. our top stories: hurricane lane heads closer to hawaii —

some areas are dealing with catastrophic flooding. hawaii is going to be impacted by hurricane lane. the question is how bad. president trump cancels his envoy‘s trip to north korea, saying there's not enough progress on denuclearisation. a british couple die suddenly in an egyptian hotel — their family don't believe the official explanation. an online sensation: two youtube stars go head to head in the boxing ring — and millions of dollars are at stake.