Legendary explorer Robert Swan knows all about setting records: in 1989 he became the first person to walk to both the North and South Poles.  Almost three decades later and the 61 year old was once again back at the South Pole, only this time he was accompanied on the 600 mile trek by his son Barney.  The father and son team was out to show the world what can be achieved with renewable energy.  A point well and truly made for, using NASA-designed ice melters, advanced biofuels provided by Shell and with solar panels strapped to their sleds in temperatures as low as -40C (-40F), the pair completed the South Pole Energy Challenge in 57 days.  Carrying the advanced technology, which added an extra 30kg to their load, did have its drawbacks however.  Speaking to MailOnline, the 23 year old Swan said: ‘It was heavier than normal to carry that technology…I definitely had a couple of moments where I wanted to pack it in and go home and warm up my feet. I had two days where I couldn’t feel my feet at all which is the danger zone when it comes to frostbite.’  As for Swan senior, he had to miss part of the trek, after struggling to keep up with the 12-mile-a-day pace, but he was able to rejoin his son for the last 60 miles. ‘For me at the age of 61 this was a tall order, you’re an old man in my business when you’re 35.  Barney took a fearful bashing with his feet, he nearly lost several days, had Antarctica slammed probably two or three more days of -40C at him, he wouldn’t be hobbling around, he’d have lost his toes.  He was only 23, this was a remarkable effort of a young man to inspire his generation into action.’  Mr Swan added: ‘What we’ve seen in Antarctica is that there is change and we need to respond to that change…In a small way and in a polite way we hope that we can prod people a little bit to say that if these two guys who look like somebody forgot to bury them have tried, what are we doing?’  As well as promoting renewable energy, the expedition has brought father and son closer together.  Barney said: ‘My father was the first person to walk to the North and South Pole and I understood what that meant but I never really felt what that meant.  I bonded with him in a way I didn’t really think was possible and understood more than I ever have what his legacy really means.’  Sounds like a serious case of like father like son.