What can I use as a portable power supply for electronics?

Yes, Use a "Powertraveller SG-010 Solargorilla Portable Solar Charger for your Notebook/Laptop, Cell Phone and other Hand-held Tendency!"

Product Description
Dimensions: 10.4" X 7.8" X 0.74". Weight Lonesome 1.5 lbs. Output Capacity: 500 mAh @ 20V and 500 mAh at 5V. Water Resistant: YES (except for the power connectors). Green LED charging indicator. Includes: 15 connectors pack: 8 staminate notebook connectors and 9 "monkey nuts" connector tips for mobile/cellphones clearly labelled on the pack. Connector tips for cellphones: Nokia & Mini Nokia, Motorola V66, Samsung E900, LG Chocolate and Sony Ericsson heavy connectors. Mini USB for Motorola Razr V series, BlackBerrys and Bluish tooth headsets. Female USB charging tip for smart phones, PDAs and other USB powered tendency. Micro USB all for the latest Motorola and Nokia series.

Solargorilla's 24 volt and 5 volt USB socket survive the ultimate renewable power station for your laptop, animated telephone, iPod and more devices. Solar gorilla plant via ii PV (photovoltaic) solar panels, which generate electric popular once they are exposed to pallid. The green LED by the solargorilla indicates the strength of charge - the more UV intensity - the better it will work! The technically advanced solar panels guarantee superb power and safe performance, all housed within a tough out shield. Suit Note: To use with Macbook Pro, Macbook Air and Macbook you will need an Pome MagSafe Hosepipe Adaptor (Visible at Apple Store) .