That old problem is energy storage (and release). For as much as activists rant about a darn efficient combustion engine, batteries - including the acid rain they bring - don't get a mention any more. They have moved on to protesting fracking, wind power, and every other form of generating energy. Acid rain worries due to energy storage is very 1980s. If they care about the environment, they should be lobbying for more battery research instead of spending a lot of money insisting 400 miles of pipeline on the Ogallala aquifer, in addition to the 20,000 miles we already have, will kill the planet.
As Boeing's new supposedly ultra-efficient 787 Dreamliner can attest, storage is a big deal and cooked lithium-ion batteries can be a billion-dollar problem - not to mention a public relations headache. So while we squandered $72 billion of taxpayer money on a green energy pipe dream, we have wasted the chance to improve the real bottleneck - that bottleneck being that the most advanced battery technology in use, lithium ion, has been around since Jimmy Carter was president.
What is the government solution to the storage crisis we face? The same Cold War mentality we have been stuck with for longer than I have been alive - yet another "Manhattan Project", this time for batteries. Batteries are not easy, there is a reason why they have not changed much in 150 years. They work pretty well, in their limited roles. A new, 21st century energy storage solution means understanding chemistry, materials, engineering, manufacturing and byzantine government safety standards that all lead to giant cost headaches. Who is the least qualified to be able to solve all of those complex issues? The government.
For big deployments, like a giant airplane, lithium ion is actually more dangerous than a lead acid battery; the electrolyte is more flammable. So what is the solution? Well, we have national labs and there are smart people there who might like to be part of the first big improvement in energy storage since Alessandro Volta in 1800. 150 years in cars means current batteries have served us well, but it's time to move on. Or we could do it the way we put a man on the moon and hire a lot of companies that are not crippled by bureaucracy the way modern NASA is, but that is unlikely, at least for the next few years.
So we are stuck with government-controlled science. The problem is that we are going to get a new head of the Department of Energy and President Obama has shown a penchant for science activists rather than pure scientists - current DoE head Dr. Stephen Chu was obsessed with CO2 rather than energy, for example, he wanted $9 a gallon gasoline, leading him to be swayed by political activists insisting that if we mandate and subsidize solar power, the miracle of capitalism will make it work. The black eye for all those energy company bankruptcies is on him but it shouldn't be; his boss has shown he hates energy so Chu's replacement is likely to be someone whose primary credentials are being old and against nuclear power, rather than young and inventive enough to take us into a clean energy future.