Early on a Tuesday morning, Hu Pennington found himself being prepped for surgery that he had hesitated to tell his family about.

As his stomach was painted with an orange antiseptic, the thought crossed his mind: "It'd be really embarrassing if I died."

Hu is one of the few Australians who volunteered to donate a kidney to a stranger.

"As they were preparing me for surgery … I saw the cooler bag that the kidney was going into," Hu told triple j hack.

"[It] was inside someone … by the end of the day."

'This century's biggest idea'

"Effective altruism" is what inspired Hu to donate his kidney and 10 per cent of his income for life.

He is on the board of Effective Altruism Australia and says the movement encourages people to do the most good they possibly can.

"To try to do good in your life, in the world, with your time, with your money," he says.

The concept of effective altruism originated in Oxford lecture halls and has been championed by Australian philosopher Peter Singer.

The movement was recently described as "this century's biggest idea" by British publication The Economist.

Loading...It has also been criticised for oversimplifying morality and focusing on increasingly "stranger" causes. Some in the Trump administration have called it "dystopian" and "dangerous".

But Hu says, while there are some strange ideas, the Effective Altruism Movement is committed to helping the global poor, "helping kids who don't really have a chance to get past the age of five".

Having seen the impacts of malaria on a friend, he focuses some of his giving on malaria bed nets.

Giving well

Every year, Hu sets aside 10 per cent of his income to support global health and development causes.

He says the financial pledge gives him agency when modern life can make it feel as though there is little: "whether it is politicians that make decisions about your life, or an algorithm that shows you what it wants".

"This sort of a pledge isn't something you make on a whim, it is a really lifelong commitment," he says.

When asked whether he worries he won't be able to keep the pledge as the cost of living rises, he admits it's something he thinks about.

"There certainly are a lot of pressures to living, even in Australia. But at the same time, I think as Australians, many of us are much more affluent than other people in the world."

Why Hu chose to donate a kidney

The giving hasn't always come easily. When Hu first pursued kidney donation, his GP told him to come back in "20 years", and a psychiatrist asked about his childhood and relationship with his parents.

Hu admits he was nervous about telling his friends and family about the decision.

"I was sort of worried about how people might feel about it, how people may respond, but it was overwhelmingly positive," he says.

"Almost everyone I talked to was really supportive. There was one person who asked if I was crazy."

What's life like with one kidney?

Between 2022 and 2025, only 15 people altruistically donated a kidney through the Australian and New Zealand Kidney Exchange program, according to Donate Life.

"Basically, I learnt two things: one, living without a kidney is really, really tough, and the other thing I learnt is that living with just one kidney is just fine," Hu says.

"Once I knew those two things, it became pretty obvious what the right thing to do was."

Hu recovered quickly, but doctors warned him to steer clear of combat sports, horse riding and dirt biking for life to avoid damaging his remaining kidney.

"My MMA skills were not up to scratch anyway," Hu joked.

People with one kidney live healthy lives, said Organ, Tissue and Transplant Authority deputy chair Carol Pollock, who is also chair of Kidney Health Australia.

"Provided there's no other health issues."

She says it poses limited risk for the individual but makes a big difference.

"I recognise a lot of people wouldn't just want to donate to a complete stranger," she says.

"I think people should consider donating to people that they may not even know remotely because it changes lives and transforms families," she says.

Altruistic donations account for less than 2 per cent of donations but can set off chains where multiple people get a lifesaving transplant.

Hu's donation created a chain of seven transplants. He doesn't know any of the recipients but received an anonymous letter from one telling him their life had changed dramatically.

"One of the challenges of trying to do the most good is it can be really hard to take stock and feel like you've accomplished that, like you always feel like, you can do more," he says.

"This does give me something that I can fall back on and think, 'Well, look, maybe this year hasn't gone that great for me. At least I've done this one really good thing, and I can be proud of that'.

"That kind of backstop is pretty priceless and has helped me at a number of times in my life where things have been pretty tough."