Colombia quits the fossil fuel exit coalition it founded, as Ireland and Tuvalu take it over at COP31

The stories

17 on this beat today.

Every story told the same way: what happened, who is involved, why it matters, how it works, the truth and the good news.

1. 01

   Colombia quits the fossil fuel exit coalition it founded, as Ireland and Tuvalu take it over at COP31

   57

   countries at the coalition's first meeting, in Santa Marta in April

   it was built for open talks, with no binding deadlines [1]

   23

   countries with road maps off fossil fuels, or plans to write one

   Joeri Rogelj says only a handful have published one [1]

   18

   Democratic US lawmakers who arrived at COP31 on Saturday

   the Trump administration has stayed away for a second year [6]

   What happened

   • Colombia has quit the Santa Marta coalition, a group of countries planning to move off coal, oil and gas. [1]
   • Colombia led it with the Netherlands, and Ireland and the Pacific island nation of Tuvalu now take over that lead. [1]
   • Ireland's government confirmed the exit and said a formal handover will happen at COP31, the UN climate talks in Turkey. [1]
   • "This process is bigger than any one country," Ireland's climate department said. [1]
   • Colombia's new president, Abelardo de la Espriella, took office in August promising to strengthen the country's oil and gas industry. [1]
   • His leftist predecessor, Gustavo Petro, had stopped awarding new oil and gas exploration contracts. [1]
   • De la Espriella won a close run-off vote after promising a total turn from Petro's agenda. [5]
   • His environment minister, Fabio Arjona, says limits on gas helped leave Colombia short, so some industries burned dirtier fuels. [1]
   • Natalie Jones, at a research group called the IISD, counts 23 countries with road maps or plans for one. [1]
   • A road map sets out how a country will cut its use of coal, oil and gas. [1]
   • Finland published its own road map at COP31, after France, Germany and the Netherlands. [4]
   • Brazil, last year's COP host, published a voluntary world road map on 3 November and presented it at COP31. [1]
   • An early outline of a COP31 deal proposes to recognise that road map and set up a process for it. [1]
   • Irene Velez, Colombia's former environment minister, told COP31 that gas, coal and diesel should not power electrification. [2]
   • Agreements at COP31 need the consent of nearly 200 countries, so progress is often slow. [4]

   Who is involved

   • Ireland and Tuvalu a European country and a Pacific island nation; they take over leading the coalition
   • Tuvalu new co-leader, in the Pacific
   • Abelardo de la Espriella Colombia's president since August; promised to strengthen oil and gas, and his government left the coalition
   • France, Germany, Netherlands road maps already
   • Finland published one at COP31
   • Irene Velez Colombia's former environment minister and a founder of the coalition; says it has 'a life of its own'
   • Joeri Rogelj a climate policy professor at Imperial College London; says progress since Santa Marta has been limited

   How it unfolded

   The coalition began in April at a meeting in Santa Marta, a city on Colombia's coast, with 57 countries. [1]

   More than 80 countries had wanted last year's COP30 talks to start a plan to phase out fossil fuels. [3]

   A handful of oil states led by Saudi Arabia blocked it, relying on a disputed rule that all must agree. [3]

   So the countries that wanted a plan met on their own in Santa Marta. [3]

   1. This week handover at COP31
   2. Jul 2027 second meeting planned, in Tuvalu [1]
   3. 3 Nov Brazil publishes the road map
   4. A week later presented at COP31
   5. 2023 COP28 agrees to transition away from fossil fuels, with no timetable [1]
   6. 2025 a few oil states block a fossil fuel road map at COP30 [3]
   7. Apr 2026 57 countries meet in Santa Marta, Colombia [1]
   8. Aug 2026 de la Espriella takes office promising more oil and gas [1]
   9. Nov 2026 Colombia out; Ireland and Tuvalu take over [1]

   Why it matters

   The exit comes as COP31 weighs Brazil's road map. [1] The talks are due to close on 20 November. [7]

   Think it through

   1. 1

      How big is this group next to the talks?

      57 countries came to Santa Marta, and 23 now have road maps or plans for one. [1] COP31 has nearly 200. [4]

      At Santa Marta57 countries

      With road maps23 countries

      At COP31200 countries
   2. 2

      Then who holds the power inside the talks?

      At these talks every country must agree, so a handful of oil states could block a plan at COP30. [3]

      80+ countrieswanted a plan

      vsvs

      A few oil statessaid no
   3. 3

      So why build it outside the talks?

      Outside the talks no one can veto it, so the willing write their own road maps and hope others follow. [3]

      Willing countries→Their own road maps→Others may follow
   4. 4

      Does a road map actually cut fossil fuels?

      Not by itself: Brazil's road map is voluntary, says the IISD's Natalie Jones. [1] Finland's sets no legally binding deadline. [4]

   5. 5

      What would make the group matter more?

      Winning over big oil and gas producers could decide whether the coalition becomes a real force in energy. [1]

   6. 6

      Is the US in any of this?

      The Trump administration has stayed away from COP31 for a second year. [6] But 18 Democratic US lawmakers arrived on Saturday. [8]

      US governmentstays away

      vsvs

      Democratic lawmakers18 came
   7. 7

      So what is really going on?

      Inside the UN talks, a few countries can stop a plan for all. [3] So the countries that want one are building it outside, where one exit does not stop it. [1]

      All must agree inside→A few can block→Plans move outside

   How it works

   Why a group of countries can carry on after its founder walks out

   International relations scholars call shared rules and meetings a regime: once built, it is cheaper to keep than to start, so it can outlast its founder.

   The twist

   Starting a club of countries takes years of meetings and trust. Once it has members, plans and dates, losing the country that started it costs far less than starting again.

   The picture

   Colombiafounder, has left

   ↓→

   Netherlandsco-leader

   ↓→

   Ireland and Tuvalunew leaders

   Step by step

   1. 1 A few countries set up shared rules and meetings
   2. 2 Building them takes years of talks and trust
   3. 3 Once running, they cost little to keep going
   4. 4 So when the founder leaves, others take the chair

   The same force, elsewhere today

   Where this chain is also running, in today's other stories.

   • COP31 reaches halfway

     the talks run for a second year with no US government team, and 18 Democratic lawmakers came instead: the meetings and rules carry on without the member that left.

   Where you've seen this

   World trade rules

   the World Trade Organization's rules kept running even after the US, one of its founders, blocked its appeals court.

   Open-source software

   projects such as the Python language kept going after their founders stepped back, because many people already maintain the code.

   A town festival

   runs year after year after its first organisers move away, because the stalls, the date and the habits are already set.

   The catch

   A regime outlives its founder only while the other members still gain from it. If they drift away too, the meetings stop.

   And the whole of it

   Colombia's voters chose a government that wants more oil, and the coalition carries on without it, led from Ireland and Tuvalu. Most of the rules any of us live under, from school timetables to trade deals, were set up by people who later left. They are kept going by people who joined after.

   The truth

   • What is really going on Colombia left the fossil fuel exit coalition it helped found after electing a president who promised more oil and gas, and Ireland and Tuvalu are taking it over. [1]Inside COP31 every country must agree, so the coalition builds its road maps outside the talks, where one exit does not stop it. [4][3]
   • Joeri Rogelj, a climate policy professor in London, called Brazil's plan "more a transitioning mood board than a map". [1]
   • Nobody knows yet

     Whether COP31's final deal will recognise Brazil's road map off fossil fuels.

     An early outline proposes it, but any one of nearly 200 countries can hold it up, and the talks close on 20 November. [1][4][7]

   • Nobody knows yet

     Whether Colombia will come to the coalition's 2027 meeting at all.

     Neither its environment ministry nor Colombia's presidential office answered questions about its plans. [1]

   What comes next

   The coalition still plans to publish a progress report at COP31 this week, with new national plans. [1]

   A second meeting is planned for July 2027 in Tuvalu, with events in Ireland before it. [1]

1. 02

   COP31 reaches halfway, far from a deal

   What happened

   • COP31, the UN climate talks in Antalya, Turkey, reached their halfway point on Saturday with countries still far apart. [7]
   • They are split on money to help poorer countries adapt, on defending climate science, and on leaving fossil fuels. [7]
   • Simon Stiell, the UN's climate chief, urged countries to "avoid tactical delays" as the second week begins. [6]
   • A first draft of the deal is expected next week, says Australia's Chris Bowen, who chairs the negotiations. [6]
   • 18 Democratic US lawmakers arrived on Saturday to back climate action, after their party's midterm election win. [8]

   Who is involved

   • Chris Bowen chairs the talks; draft due next week

   How it unfolded

   1. Next week first draft of the deal
   2. 20 Nov talks due to close

   Why it matters

   Poorer countries need the deal to settle money for adapting to climate harm. [7]

   Think it through

   1. 1

      Why do the talks move so slowly?

      Every one of nearly 200 countries must agree, so progress is often slow and small. [4]

      Nearly 200 countries→All must agree→Slow progress
   2. 2

      Who is missing from the table?

      The US government has snubbed the talks for a second year in a row under President Trump. [6]

   3. 3

      Is anything moving outside the formal deal?

      Turkey is asking countries to sign a voluntary pledge to make electricity a bigger share of energy use. [7]

   The truth

   • "There's no climate quick fix," Stiell said, and the summit is not expected to bring a major breakthrough. [7]

   What comes next

   The talks are due to close on 20 November. [7]

2. 03

   Thousands march in Antalya

   What happened

   • Thousands of people marched through Antalya on Saturday, in the biggest protest since COP31 began on Monday. [7]
   • Marchers were searched twice on the way in, and steel barriers sealed the whole route. [9]
   • Turkey often bans big public gatherings, but it let this rally go ahead. [6]
   • LGBTQ+ activists marched with rainbow flags, ringed by other groups, despite a Turkish crackdown since September. [9]
   • "We can do this because the eyes of the international media are here," said Ozgur, a 20-year-old activist. [9]

   Who is involved

   • LGBTQ+ activists marched, ringed by others

   Why it matters

   It came as negotiators head into the final week, with activists angry at slow progress. [7]

   Think it through

   1. 1

      What do the marchers want from COP31?

      Tougher curbs on fossil fuels, and new pledges to help poorer countries adapt. [7]

      Fossil fuelstougher curbs

      ++

      Poorer countrieshelp to adapt
   2. 2

      Why does the host country matter here?

      A protest leader said Turkey co-chairs COP31 yet has no road map off fossil fuels and is opening coal mines. [7]

      TurkeyCOP31 co-chair

      vsvs

      New coal minesopening
   3. 3

      Who else used the march?

      An Indonesian activist marched to draw attention to forest fires in her country that have burned for months. [9]

   How it works

   Sociologists who study protest call this a political opportunity: a moment when marching costs less than usual.

   Ozgur said police would usually not allow the rainbow flag, but world media in Antalya made it possible. [9]

   Seen it before

   Pupils behave better in the playground on the day the head teacher is watching.

   The truth

   • Police counted more than 7,000 marchers. [7] Organisers said tens of thousands. [6]
3. 04

   Greenpeace boulders sit on a wind farm site

   What happened

   • Greenpeace dropped about 15 tonnes of boulders, each up to 2 tonnes, into the North Sea off Norfolk, England. [10]
   • It wanted to stop bottom trawling, fishing with nets on the seabed, which it says is wrecking a protected area. [10]
   • Most of the boulders landed on the site of Norfolk Vanguard, one of Britain's biggest planned wind farms. [10]
   • Greenpeace had no consent from the marine authority, and did not know about plans for Vanguard East. [10]
   • Developers led by RWE, a German power company, agreed a £12bn deal this week to build the wind farms. [10]

   How it unfolded

   1. Next year building starts
   2. 2030 fully running

   Why it matters

   RWE is checking whether the boulders affect the building work, due next year, or its undersea cables. [10]

   Think it through

   1. 1

      Will the boulders really hold up the wind farm?

      Probably not for long: the boulders are likely to be removed within months, the Guardian reports. [10]

      Boulderson the site

      ↓→

      Within monthslikely removed
   2. 2

      Why is Greenpeace not worried?

      Greenpeace UK's Will McCallum says wind firms routinely move natural boulders, some 10 times heavier than these. [10]

      up to 2 tonnesGreenpeace boulders

      vsvs

      up to 10x heavierNatural boulders
   3. 3

      What happens to the fishing there?

      Trawlers are likely to move away from the area anyway while the wind farm is built. [10]

      Wind farm built→Trawlers move elsewhere

   How it works

   Planners call sharing out one stretch of sea between its uses marine spatial planning.

   Off Norfolk, a trawled fishing ground, a protected area and a wind farm site are the same patch of seabed. [10]

   Seen it before

   Three clubs booking the same school hall for one evening have to agree who gets it.

   What comes next

   The wind farms are due to be fully running in 2030. [11]

4. 05

   Germany's solar heads for a record year

   What happened

   • Germany's solar panels had made 90.2 terawatt-hours of electricity by 27 September, says BSW-Solar, the solar industry group. [12]
   • That is already more than the 90 terawatt-hours solar made in the whole of 2025. [12]
   • So 2026 is likely to pass 100 terawatt-hours, almost 10 times what Hamburg, a big city, uses in a year. [12]

   How it unfolded

   20 years ago, German solar made 2.2 terawatt-hours. [12]

   Why it matters

   BSW-Solar says everyone gains from cheaper power, fewer energy imports and less climate damage. [12]

   Think it through

   1. 1

      Is the record all down to more panels?

      No: an above-average number of sunshine hours helped as well as more panels, the group says. [12]

      More sunshineabove average

      ++

      More panelsgrowing
   2. 2

      Is solar now Germany's biggest source?

      Solar made 17.8% of Germany's home-made power, behind wind, the top source, and then coal. [12]

      Windfirst

      ++

      Coalsecond

      ++

      Solarthird, 17.8%

   How it works

   Energy engineers call the share of the year a power plant runs at full output its capacity factor.

   The same panel makes more power in a sunnier year, so sunshine and new panels added up this year. [12]

   Seen it before

   A lemonade stand sells more on a sunny weekend, even from the same table.

   The truth

   • The record forecast and the cheaper-power claim both come from BSW-Solar, an industry association. [12]

   Good news

   • Germany's solar panels made 90.2 terawatt-hours of electricity by 27 September, more than they made in the whole of 2025.
5. 06

   Sunny Great Lakes, cloudy Southwest

   What happened

   • October brought 14% more sunshine than normal to the US Northeast and Great Lakes, says Solcast, a solar data firm. [13]
   • Buffalo, in New York state, had its sunniest October in Solcast's records, which begin in 2007. [13]
   • The US Southwest got 9% less sunshine than normal, after an unusually wet month. [13]
   • Phoenix, in Arizona, had about 10% less than its October average, its second-lowest October on record. [13]
   • A low-pressure system drew Pacific moisture in, helped by Tropical Storms Polo and Trudy. [13]

   Why it matters

   Many big solar farms sit between Southern California and Arizona, so they all lost sunshine at once. [13]

   Think it through

   1. 1

      Why does the average look so calm?

      Across North America, sunshine was only 0.8% above normal, which hides both regions' swings. [13]

      0.8%above normal across all of North America

   2. 2

      Who pays for this kind of data?

      Solcast says more than 350 companies, running over 350 gigawatts of solar, use its data. [13]

      350companies using Solcast's sunshine data

   How it works

   Solar scientists measure the sunlight reaching flat ground as global horizontal irradiance, or GHI. [13]

   Clouds block that sunlight, so the wet Southwest's GHI fell 9% while the drier Northeast's rose 14%. [13]

   Seen it before

   A garden solar lamp glows for less time after a cloudy day.

6. 07

   Supercell storms hit eastern Australia

   What happened

   • Storms dumped heavy rain across northern and eastern New South Wales and much of Queensland on Saturday. [14]
   • Winds reached 98 km/h in Goulburn, and 30 to 50 mm of rain fell around Coffs Harbour. [14]
   • A man in his 20s was struck by lightning while swimming at Ettalong beach, and is critical but stable. [14]
   • Witnesses said the beach was sunny, but lightning can strike up to 30 km from the centre of a storm. [14]
   • The Bureau of Meteorology warned of supercell storms on Sunday, with hail over 5 cm and winds over 120 km/h. [14]

   How it unfolded

   1. Sunday north-east NSW
   2. Monday south-east Queensland

   Why it matters

   The storms could bring life-threatening flash floods to places including Brisbane and the Gold Coast. [14]

   Think it through

   1. 1

      What sets off storms like these?

      A southerly change pushing up the NSW coast is the trigger, says the bureau's Sarah Scully. [14]

      Southerly change→Pushes up the coast→Supercell storms
   2. 2

      Why is the rain so hard to predict?

      Rain totals from a coastal low depend on how close it sits to the coast, and how long it stays. [14]

   How it works

   Meteorologists call a dip of low pressure running along a coast a coastal trough. [14]

   A trough off the NSW coast should bring 30 to 70 mm, but far more if it moves closer. [14]

   Seen it before

   A garden hose soaks one spot when you hold it still, and spreads thin when you sweep it.

   What comes next

   On Monday the risk moves to the NSW northern rivers and south-east Queensland, including Brisbane. [14]

7. 08

   Exmouth port plan draws a fight over whales

   What happened

   • A deepwater industrial port is planned just outside Exmouth, a tourist town 1,230 km north of Perth in Western Australia. [15]
   • The Gascoyne Gateway would have a jetty wharf, fuel storage, a solar farm and a seawater desalination plant. [15]
   • It would serve cruise liners, defence and supply ships, with building due from early 2029 if approved. [15]
   • Author Tim Winton says it would bring up to 600 vessels a year into a humpback whale nursery. [15]
   • Locals fear dredging silt could smother seagrass meadows where dugongs feed and nurse their calves. [15]

   How it unfolded

   1. Now public consultation
   2. Early 2029 building could start

   Why it matters

   The fight sets new jobs and roads against the whales and dugongs beside World Heritage Ningaloo. [15]

   Think it through

   1. 1

      Do most locals oppose it?

      The port's chief executive calls opponents a "loud minority" and says most locals back it. [15]

   2. 2

      Are there ships there already?

      The company says commercial ships already move around wildlife in the gulf today. [15]

   3. 3

      Who decides?

      Western Australia's environment watchdog, the EPA, is now asking the public for views. [15]

   How it works

   Environmental assessment is how a project's harm to wildlife is weighed before anyone approves it.

   WA's EPA is taking public views first, so the dugong and whale worries go on record before any decision. [15]

   Seen it before

   Before a new skate park opens, neighbours get a say on the noise and parking.

   The truth

   • Nobody knows yet

     Whether the Exmouth port will be approved.

     Western Australia's environment watchdog is still taking public views, and the two sides disagree on what most locals want. [15]

8. 09

   Maui fire survivors' health study runs short

   What happened

   • Two University of Hawaii professors have tracked the health of 2,500 survivors of the 2023 Maui wildfires. [16]
   • Their study, MauiWES, tests survivors' blood, lungs and mental health, and links them to therapy, food and cash help. [16]
   • Federal money to keep the study going was uncertain, and state funding it counted on fell through this spring. [16]

   How it unfolded

   The August 2023 fires killed at least 102 people and destroyed more than 2,200 buildings. [16]

   Three years later, just 15% of those buildings have been rebuilt. [16]

   Why it matters

   About a third of Lahaina's residents were born outside the US, and the study works in Spanish and Tagalog too. [16]

   Think it through

   1. 1

      Why test survivors for years?

      The tests track what survivors were exposed to, such as ash breathed in while clearing the burn zone. [16]

   2. 2

      Who pays for it?

      It runs on grants, and its applications for federal money met months of silence. [16]

   3. 3

      Is Maui safe from fire now?

      Wet spring storms grew grass that dries into tinder, which raises the fire risk later in the year. [16]

      Wet spring→More grass→Dry tinder later

   How it works

   Public health researchers call a study that follows the same people for years a cohort study.

   The team aims to test the same survivors every year, so changes in their health show up over time. [16]

   Seen it before

   Marking your height on the same door frame each birthday shows how much you grew.

   Good news

   • About 2,500 survivors of the 2023 Maui fires have had free health checks through one university study, with therapy, food and cash help alongside.
9. 10

   A year of extreme weather, counted

   What happened

   • The Guardian estimates 2026's extreme weather has already killed people in the high tens of thousands. [17]
   • It follows the world's hottest summer since records began in 1850. [17]
   • Europe's summer heat killed an estimated 50,000 people in its cities, two-thirds of them deaths linked to climate change. [17]
   • In August, a glacier collapse in Nepal killed at least 1,300 people. [17]
   • Haze from Indonesia's worst fire season in a decade is estimated to have killed 3,560 people in one month. [17]
   • Global temperatures have tied the record of 2.04C above pre-industrial levels, set in 2023. [17]

   How it unfolded

   1. 1850 records begin
   2. Summer 2026 hottest on record

   Why it matters

   The UN's disaster agency has told countries to prepare for a strong El Nino peaking around the year's end. [17]

   Think it through

   1. 1

      Did climate change cause all of this?

      Not all: two-thirds of Europe's heat deaths were linked to it, and warmth was a likely cause in Nepal. [17]

   2. 2

      Is anything going the other way?

      Fossil fuel emissions will likely fall this year, as high prices after the US-Israeli attack on Iran cut use. [17]

      High oil and gas pricesafter the Iran attack

      ↓→

      Emissionslikely to fall

   How it works

   Climate scientists call working out how much warming changed a disaster's odds attribution.

   For West Africa's May and June rains, warming made the record downpours 5 times more likely and 23% more intense. [17]

   Seen it before

   Loaded dice can still land on any number, but they land on a six more often.

   The truth

   • The Guardian calls its own death toll a conservative estimate that is certain to rise. [17]
10. 11

    A three-minute health test for used batteries

    What happened

    • UNSW researchers in Sydney built a prototype that checks a used battery's health in under 3 minutes a cell. [18]
    • Today's test runs a full charge and discharge over about 10 hours, costing about AUD 120 a car battery pack. [18]
    • The new test sends short electrical pulses through each cell, and statistics estimate its health with over 90% accuracy. [18]
    • They aim to bring the cost under AUD 25. [18]

    Why it matters

    A fast, cheap test helps decide which old car batteries can store power for the grid instead of being scrapped. [18]

    Think it through

    1. 1

       What is wrong with the slow test?

       Hours of hard cycling can overheat damaged batteries and even start fires, the researchers say. [18]

    2. 2

       Is an old battery worth saving?

       Up to 95% of a battery's parts can be recovered, but only a small share of Australia's are collected. [18]

       95 of 100

       of a battery's parts that can be recovered

    How it works

    Battery engineers call how much of its first capacity a cell still holds its state of health.

    A recycler that knows each cell's health can reuse strong cells and recycle weak ones, without 10 hours of testing. [18]

    Seen it before

    A shop checks a second-hand phone's battery before deciding to resell it or scrap it.

    The truth

    • The 90% accuracy comes from lab tests, and the trial on real recycled batteries is still to come. [18]

    What comes next

    A AUD 1.3 million trial with DY New Energy, a Malaysian recycler, will test it on over 500 batteries. [18]

11. 12

    CATL details its sodium battery for grids

    What happened

    • Battery maker CATL has given new details of Tener Sodium, its sodium-ion battery for power grids. [19]
    • One block of 8 cabinets stores more than 30 megawatt-hours, enough to give 7.5 megawatts for four hours. [19]
    • Each cabinet weighs about 44 to 45 tonnes. [19]
    • CATL says it keeps 70% of its health after 20 years of use. [19]
    • A lithium iron phosphate version in the same cabinets would store about 50 megawatt-hours. [19]

    Why it matters

    Developers can choose sodium or lithium for the same cabinets when they design a project. [19]

    Think it through

    1. 1

       Why pick sodium if it stores less?

       It copes with deep cold: CATL reports it keeps over 92% of its capacity at minus 20C. [19]

       92%of capacity kept at minus 20C

    2. 2

       How long does it last?

       At launch CATL reported 15,000 charge cycles at 25C, and over 10,000 at 45C. [19]

       15,000charge cycles at 25C, CATL says

    How it works

    Battery engineers compare chemistries by energy density: how much a battery stores for its size.

    The same 8 cabinets hold about 30 megawatt-hours as sodium and about 50 as lithium, so sodium needs more space. [19]

    Seen it before

    A bag of feathers and a bag of sand can be the same size, but the sand weighs far more.

    The truth

    • Nobody knows yet

      Whether CATL's sodium battery will match its own figures.

      The numbers come from CATL's slides, and certification of the sodium version is still to come. [19]

12. 13

    Huawei's new home battery

    What happened

    • Huawei, the Chinese tech firm, has launched the Luterra S2, a home battery with its own inverter built in. [20]
    • Single-phase versions give 3 to 10 kW, and three-phase versions up to 20 kW. [20]
    • The basic version stores 5 kWh, enough for essentials like lights during a power cut. [20]
    • It uses silicon carbide parts, which Huawei says make it smaller, lighter and more efficient. [20]
    • Huawei says it runs below 29 decibels with no fans, about as quiet as a small computer. [20]

    Why it matters

    It is built to take on Tesla's Powerwall, but Electrek says it probably won't reach the US soon. [20]

    Think it through

    1. 1

       Why put a battery in a home?

       Home batteries store solar power and keep a house running when the grid goes down. [20]

    2. 2

       What is new about it?

       Its battery, inverter and power controls come in one stackable box, which Huawei says installs in minutes. [20]

       Batterystackable

       ++

       Inverterbuilt in

    How it works

    Electrical engineers call the box that turns a battery's power into household mains power an inverter.

    The Luterra S2 puts that inverter in the same box as the battery, so one unit does both jobs. [20]

    Seen it before

    A phone charger turns the wall's power into the kind a phone can use.

    The truth

    • Its quietness and quick installing are Huawei's own claims. [20]
13. 14

    Nissan's $19,400 plug-in hybrid

    What happened

    • Dongfeng Nissan opened early orders this week for the NX7, a plug-in hybrid priced at 129,900 yuan, about $19,400. [21]
    • Its 40 kWh battery gives up to 320 km, about 198 miles, on electric power alone. [21]
    • A 1.5-litre petrol engine joins in on long trips, for up to 1,666 km in all. [21]

    How it unfolded

    Nissan's first Leaf electric car managed about 70 miles from a 24 kWh battery. [21]

    Why it matters

    Electrek says it could suit North American drivers afraid of being caught without a charger. [21]

    Think it through

    1. 1

       So is it really an electric car?

       Electrek calls it an electric car for the 360-odd days a year of drives under 200 miles. [21]

       Most dayselectric

       vsvs

       Long tripspetrol
    2. 2

       Does it still burn petrol?

       Yes, on long trips. [21] Nissan's Rogue Hybrid, which has no plug, runs entirely on fuel. [21]

    How it works

    Engineers sort hybrids by whether they plug in: a plug-in hybrid has a big battery charged from the wall.

    The NX7's 40 kWh battery covers most daily driving on electricity, while the Rogue Hybrid has no plug at all. [21]

    Seen it before

    A bike with a small motor lets a rider pedal most days and use the motor up steep hills.

    The truth

    • The 320 km electric range is Nissan's own promise, not a measured road test. [21]
14. 15

    Rubber blades for tidal turbines

    What happened

    • Engineers report in Nature that flexible rubber blades could make tidal turbines tougher and cheaper to run. [22]
    • Tidal power is very predictable, but rough water hits the turbines with heavy, changing loads that raise their costs. [22]
    • Big turbines today twist each blade with costly machinery to soften those loads, called active pitch control. [22]
    • In tests at the University of Edinburgh, the rubber blades made as much energy as rigid blades with that control. [22]
    • They also cut the rapid load swings that wear turbines out by up to a third. [22]

    Why it matters

    Tougher, simpler turbines could make tidal power, which is steady and predictable, cheaper to produce. [22]

    Think it through

    1. 1

       Why use rubber instead of machinery?

       The blade bends by itself under load, flattening its curve, so it needs no extra machinery. [22]

       Strong currentpushes

       ↓→

       Rubber bladebends flatter
    2. 2

       Is it in the sea yet?

       No: the results come from experiments over simulated tidal cycles in a test tank. [22]

    How it works

    Engineers call a shape that bends with the flow, and so changes the force on it, aeroelastic.

    When the current surges, the rubber edge flattens, so the blade catches less of the surge and its load drops. [22]

    Seen it before

    A tree's branches bend in a gale, so the wind pushes on them less and they do not snap.

15. 16

    Bamboo and solar glass for cooler skylights

    What happened

    • Researchers at India's Vellore Institute of Technology paired see-through solar panels with see-through wood in a skylight. [23]
    • They make wood clear by removing lignin, the part that absorbs light, and filling it with clear resin. [23]
    • Of balsa, poplar, pine and bamboo, bamboo let the least heat through at every level of see-through. [23]
    • They estimate a saving of about $20.32 a square metre a year on cooling. [23]

    Why it matters

    A skylight that lets in less heat cuts air-conditioning costs in hot places like Vellore. [23]

    Think it through

    1. 1

       How much carbon does it save?

       The 60% see-through panel with bamboo avoided about 0.058 tonnes of carbon dioxide a year, they estimate. [23]

       0.058tonnes of carbon dioxide a year avoided

    2. 2

       Why add wood to the solar glass?

       The wood layer stays see-through but blocks heat getting into the room below, the researchers say. [23]

    How it works

    Building engineers call the heat that sunlight brings in through windows solar heat gain.

    Bamboo cut that gain the most, so the room needs less air conditioning to stay cool. [23]

    Seen it before

    Closing the curtains on a sunny afternoon keeps a bedroom cooler.

    The truth

    • The tests used cardboard model buildings 12.5 cm wide, lit by halogen lamps, not real roofs. [23]
16. 17

    Sharjah frees 15 rescued green turtles

    What happened

    • Sharjah's environment agency released 15 green sea turtles off the UAE's east coast after up to a year of care. [24]
    • Many had been hit by boats or propellers, or lost flippers to ropes and fishing lines. [24]
    • Most were found sick or worn out, perhaps after migrating from nesting beaches in Oman. [24]
    • They were set free late last month in the Al Qurm Protected Area, carrying trackers. [24]

    Who is involved

    • Al Qurm Protected Area where they were freed

    How it unfolded

    The International Union for Conservation of Nature moved green turtles to Least Concern last year. [24]

    Why it matters

    A small piece of rope can cut off a flipper's blood and cost a turtle its limb, a researcher says. [24]

    Think it through

    1. 1

       Are green turtles safe now?

       Its global listing improved last year, but boats and fishing gear still injure turtles in UAE waters. [24]

       WorldwideLeast Concern

       vsvs

       UAE watersstill injured
    2. 2

       Who does the rescuing?

       The Sharjah Strandings Response Programme, which also rescues seabirds, dolphins and porpoises. [24]

    How it works

    Wildlife vets call this rehabilitation: treating a wild animal until it can live on its own again.

    Some turtles needed only rest and others surgery, and each spent six months to a year in care. [24]

    Seen it before

    A sprained ankle needs weeks of rest before running on it again.

    Good news

    • Fifteen green sea turtles, hurt by boats and fishing lines or worn out from migrating, swam free off Sharjah's east coast after up to a year of care.