A world powered solely by solar, wind and batteries is a limitation vs. a solution. The battery cars described by joelsapp do not exist (neither to H2FCVs in any great numbers). Miniaturizing any technology and making it mobile is a innovation constraint. Driving fewer POVs makes sense though, and so do fuel cell buses.

I have discovered that someone named Joseph Romm has inappropriately used past accomplishments in the Clinton Administration to poo-poo fuel cells without evidence or accurate argumentation. I counter folks like Romm here:

http://earthsynchub.com/esmonitor/oped/032609/addressing_the_fuel_cell_naysayers/

Hydrogen come from natural gas, water and opportunity fuels (waste to energy). Coal would be a poor solution as well are running low on that fossil fuel as well. Using what NG we have left much more efficiently, close to big energy users, would be smart and fuel cells do that. Fuel cells are therefore one of most versatile 24/7/365 all-weather power supplies. Solar and wind alone cannot supply replace all our power generation systems for a similar reliability solution, which has been a big worry for planners for years.

One of the least understood, yet highly successful track record areas for fuel cells, are stationary CHP applications. The following DOE EERE report statement helps to describe the usefulness of more CHP:

DOE-EERE statement on CHP

DOE-EERE/ORNL states that if 20% of the US stationary energy supply was powered via CHP, it would equal taking 154 million cars of the road. Huge?

“CHP, or cogeneration, has been around in one form or another for more than 100 years; it is proven, not speculative. Despite this proven track record, CHP remains underutilized and is one of the most compelling sources of energy efficiency that could, with even modest investments, move the Nation strongly toward greater energy security and a cleaner environment. Indeed, ramping up CHP to account for 20 percent of US electricity capacity—several European countries have already exceeded this level—would be equivalent to the CO2 savings of taking 154 million cars off the road.

If the United States adopted high-deployment policies to achieve 20 percent of generation capacity from CHP by 2030, it could save an estimated 5.3 quadrillion Btu (Quads) of fuel annually, the equivalent of nearly half the total energy currently consumed by US households. Cumulatively through 2030, such policies could also generate $234 billion in new investments and create nearly 1 million new highly-skilled, technical jobs throughout the United States. CO2 emissions could be reduced by more than 800 million metric tons (MMT) per year, the equivalent of taking more than half of the current passenger vehicles in the US off the road. In this 20 percent scenario, over 60 percent of the projected increase in CO2 emissions between now and 2030 could be avoided.”

- COMBINED HEAT AND POWER:
Effective Energy Solutions for a Sustainable Future, ORNL, 2008