Two subjects getting mixed together:
- All electric house loads with diesel/gas propulsion: Very much viable and there are some units being sold. Not necessarily cost effective but very much doable.
- All electric including propulsion: Not practical
On trains and ships, the system basically replaces the transmission. The gearing needed to get a mile long train moving would be huge, heavy and complicated. Electric has a major advantage because it can provide maximum torque from 0 to max rpm. As a result, it doesn't need gearing. Also, they really don't care about acceleration as they aren't trying to merge on I-95.
There is a secondary advantage. Because they don't care about acceleration, they just need an engine large enough to maintain cruising speed. A car (or MH) needs an engine with more HP to provide acceleration (ie: old VW bugs only have like 50-60hp and can cruise at 60-70mph but it takes forever to get up to that speed)
For a small car like the volt, they can get a decent range thru the small battery pack. Many people only travel 5-10miles to work, so the motor never needs to come on. If you look at most electric cars, they are small and a lot of effort is spent on aerodynamics. A short RV trip might be 100 miles continuous driving and you have the aerodynamics of a brick. The battery pack to go even 20miles would be huge.
Then once you get to your site, your generator is massively oversized for house loads. That 400hp engine might only need to put out 5-10hp if both air/con and the stove are running flat out.
For propulsion, the primary issue is energy density in battery packs (and secondarily the cost of those battery packs). If a battery the size of a gallon jug could hold even a 1/4 of the energy as a gallon of gas (at a reasonable price of course), we would see a mass conversion to electric powered cars. Currently, electric powered cars are limited to short commutes and largely depend on govt subsidies to be cost effective (even then most are compliance cars built because California requires a certain number of "zero" emission cars...even though they aren't really zero emission)
