SINGAPORE - A Singapore-registered company has won the annual Liveability Challenge, a global call for companies to come up with innovative solutions for clean energy and sustainability in tropical cities.

The competition saw an intense battle with over 300 entries from 51 countries fighting for the award sponsored by local non-profit organisation Temasek Foundation.

From hydrogen-powered engines to edible protein made from food waste, the contest pitted solutions to make cities in the tropics greener.

Sophie's Kitchen was named the winner on Friday (June 7) at the Sands Expo and Convention Centre at Marina Bay Sands.

The team beat five other finalists to walk away with $1 million in funding for their technology to produce food-grade protein using microalgae as an alternative to animal- and plant-based protein.

The innovation is expected to save large amounts of arable farmland that is required in agriculture. It also does away with herbicides, fertilisers and antibiotics.

About 0.02ha of land is needed to produce a ton of protein for the product, compared to 141ha needed for beef.

The company expects to use the protein in supplements and alternative protein food such as plant-based burgers and seafood.

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This year's competition focused on two themes - energy and circular economy.

Judges evaluated energy solutions for their ability to significantly reduce carbon emissions.

For the circular economy, the teams had to create high economic or social value out of existing waste streams or demonstrate full circularity.

In a circular economy, waste is minimised by using resources as long as possible, and products and materials are regenerated and recycled in a closed production loop.

The panel of judges included co-founder of GoImpact Hong Kong Helene Li and board member of angel investment network Bansea Shoko Suzuki.

The annual competition is part of the broader Ecosperity Week 2019 - where businesses, policymakers and experts gather to brainstorm sustainable solutions to tackle climate change in a resource-starved world.

Mr Lim Hock Chuan, chief executive of Temasek Foundation Ecosperity, said: "The six proposals at the finale are strong contenders in their respective fields and could make a big positive difference to our collective living environment."

Singapore-based biodegradable technology firm RWDC Industries was the winner in last year's competition for their fully biodegradable drinking straws made from a naturally occurring polymer.

The biopolymer, which the company branded as Solon, is produced during the bacterial fermentation of plant-based oils or sugar, and is certified to be fully biodegradable in soil, water and marine conditions.

The company launched the biopolymer, an alternative to single-use plastics, on Thursday in conjunction with Ecosperity Week.

Apart from drinking straws, the bioplastic can be used to make cutlery, cup lids, food and beverage packaging.

The firm is currently in talks with a major personal care company on using the polymer to produce diapers and wet wipes.

The team secured around $22 million in their last funding round in April this year and had previously said that the funds would be used to expand its production capacity of the polymer at its plant in United States.

Dr Daniel Carraway, RWDC's co-founder and chief executive, said: "We believe that it is our duty as stewards of the planet to use our talents, energy and time to leave a legacy of a sustainable future."