The simplest way to do this would be to have a bicycle connected to a generator, in turn connected to charge a battery. Then use an inverter to turn the electricity back into AC so it can easily power your stuff. The main problem is that you'll find it very exhausting to charge enough power to do any useful work. If you cycle really hard, you should be able to generate 500 Watts of power - but that is really hard work. Keep it up for 3 minutes and you'll have enough energy to boil a cup of water. Or don't pedal so hard and take ten or twenty minutes to boil your cuppa. Fridges and TVs are about 200 Watts each (probably less if you only have a small one for your camper van), so you should be able to keep one of them going by constant pedalling but I think it would be too much hard work to keep them both going for any length of time. And that is the main problem - it is hard work to constantly pedal for any length of time. You need to go to a science show to see how many Watts you can generate by pedalling ( and remember, your leg muscles are your strongest muscles, I can't imagine you getting much more power any other way ), then look at your different appliances and see how many Watts they need to work (my lap top is about 80 Watts). If you can't generate the required power then you'll have to pedal longer (eg if you can generate 500 Watts then if you want to use a 1000 Watt iron for five minutes then you'll have to pedal for ten minutes.) You may even want to go the next step and find out how much more food you need to eat in order to generate that extra energy. That would be a fun thing to work out. In summary, I think you should be looking for a different energy source ( solar? wind? something else? ). Have fun, I hope you find a good answer.