Question: Can anyone suggest an alternative to energy from a battery?

I'd like a system to replace my deep cycle leisure battery, I currently use [this](http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_264265_langId_-1_categoryId_165475) 110 AH leisure battery with a 1200W inverter. 
I run my computer, lighting and sound system off it while I'm "out in the sticks", It works just perfect, there's more than enough energy to get a couple of days usage between charges, I just wanted to know if there's a greener way of storing the energy - instead of using ye olde plastic box full of acid and corroding metal. 

I'm not interested in using a diesel or petrol generator, I'm looking for something a bit cleaner and greener than that, was thinking about the possibility of running a dynamo off a bottle of pressurized gas or air? - I'd probably need an unfeasibly large tank for this tho! 

Cheers Chiphackers :)

Answer: 
You could collect a lot of lumber (like >50kg), tie it all together and throw a long rope over a big tree branch. Then using several winches lift up all the lumber high in the air, and then utilise the energy of the timber slowly descending towards the ground. The winches would convert high torque to low torque but with a very long rope, which would be a good way to drive a dynamo.

Just thinking alternatively... :)
One alterna-power answer might be fuel cells. A more old-fashioned and commonly available one would be a generator running off some liquid fuel (probably diesel). You might still want a buffer battery for that, of course, but you might be able to get rid of the inverter in some cases.