The plight of the environment and the problems caused by plastic pollution may not seem like obvious topics for the Web Summit in Lisbon... but they actually play into a central theme of the tech gathering. 

Everyone here is looking for the next big idea: they're either trying to sell theirs to investors, or they are investors themselves looking for that one killer idea that will change the world. 

Lush cosmetics is one of the big anti-animal-testing voices in cosmetics and has now turned its attention to the environment.

The issue has given the company a headache for 30 years, explains Charlotte Nisbet, who is representing Lush in Lisbon: "In 2018, we launched our first naked concept shop, so our first naked packaging shop – no packaging whatsoever, so no single-use plastic packaging. And we suddenly realized there is a lot of legislation in place that means we still need labels and stickers and so we turned to technology to help us solve that.”

And that tech comes in the form of an app. Customers point their phones at a product, and the app then displays all the legal information on what's in the product that Lush has to display. 

"It just uses machine learning and image technology," adds Charlotte. "We actually have a robot called Nigel, which takes lots of different pictures of the product with these arms – it takes about 500 pictures and then it loads straight into the app. I think now's the time, consumers are really responsive to what we're trying to do, which is fantastic because we've been trying to do it for a long time and it feels like now's our chance.”

But, while Lush is an international brand with a huge presence, the smaller companies here are also hoping to make a big difference. 

It is often said the best ideas are the simplest and that's what Qwarzo thinks it has got here. It is an almost obvious idea – paper that acts like plastic. 

All of the benefits, none of the drawbacks, as CEO Manuel Milliery explains: "We apply two microns of sand to this paper and this paper turns perfectly waterproof, heat resistant, greaseproof. We do the same with the straws. This one is wet, it's humid but as you can see, it's rigid. We put it this morning in Coca-Cola and it's still perfectly intact."

He adds: "Plastic is durable and waterproof and paper is not waterproof, not greaseproof, but if it is, you can replace almost each disposable plastic with something that is 100 percent paper. And paper is fully recyclable, compostable and harmless to nature, humans, planets, the oceans.”

As the investors watch, the companies pitch. The smallest of ideas can make a massive difference and they know that here. 

Somewhere amid the 70,000 attendees could be an idea that's going to have a huge impact on the world's problems. It's just a case of finding it.