Instead of one super chunky battery, how about a laptop with replaceable batteries, in combination with a UPS?
UPS is so you can actually replace the laptop battery with a spare one , even during a power outage. Just run the laptop on AC from the UPS while changing batteries. Or see if you can find a UPS with a long lasting battery. Entry level ones only have like 15-30 minutes of battery life though, since they're more intended for safe shutdowns or brownouts.
No they're not, in fact Cosmic is almost ready for Alpha release (Sorry, couldn't help myself)