-Small and sustainable: 'Tiny houses' could be solution to world’s housing problems

-Rubbish isn’t useless – it can be converted into something entirely new, such as:

1-Free health care: Indonesia allows people to trade valuable rubbish for access to doctors - a grand idea that simultaneously tackles poverty, health care roadblocks and pollution in poor countries.

2-Home heating: Italy ships 70,000 tonnes of trash to Austria a year where it’s burnt and converted to electricity.

3-New roads: One way to become a zero-plastic society? Follow India’s lead, and take the plastic rubbish and turn it into material that can be used to pave roads.

4-Microscopic dust: Thrown-out electronics are choking landfills worldwide – but smashing them into nano-bits to create new materials might be easier and better than recycling.

5-Train infrastructure: A railway car made from a mix of concrete and old tyres increases durability, is quieter, and re-uses 35 tonnes of waste for each kilometre of rail line.

-The energy of the future is green, clean… sometimes, bizarre.

1-Pollution-monitoring moss: The EU is turning to a cheap, clean, easy-to-install sensor for contaminated air: cloned moss.

2-Monster ships made from fibre: The global economy hinges on global trade – but current cargo ships are expensive and bad for the environment. That’s why the EU is making huge, futuristic, recyclable ships made from fibre instead of steel.

3-Pee power: In the developing world, it could be enough to charge a mobile phone or power indoor lighting, Bristol researchers say.

4-Skyscrapers that morph wind and sunlight into energy: One plan in New York aims to turn America’s biggest city into a “climate laboratory” to save money and energy.

5-Covering lakes with solar panels: Population booms deplete energy resources and also crowd tiny strips of land – so countries like Japan are plopping massive solar panels on top of lakes and rivers.

-Wind-powered rail Dutch trains now run 100% on wind power. The Netherlands had aimed to achieve this ambitious goal by 2018, but ticked the box early in January.