Interesting about regenerative breaking on the downhill run. I remember seeing this UK show about a quarry railroad in Wales (slate I believe), the trains went downhill totally by coasting, the operator basically had a brake lever.
The article is a bit misleading, given this is just a proof of concept. We are in a transition period and technology may or may not be there. In the early days of the automobile, for example, there were concerns about gasoline, when cars started going from being a rare play toy to coming out in numbers, there was concern that they could pump enough oil and refine enough gasoline (among other things, early distillation tech for refining gasoline was pretty inefficient). Obviously they discovered oil in Texas and Oklahoma, and it worked out, but sometimes you don't know.
There are questions about charging ability, there is no doubt, we have a very unbalanced electrical grid, it isn't national, and there are real concerns about being able to handle all that demand (that, along with switching to heat pumps vs using gas fired furnace/boilers, lot of things). I suspect it will be addressed, the auto industry has made a big committment to electric vehicles and knowing the way things work they will be putting pressure on the power industry to upgrade the grid (my guess? the infrastructure bills they have already put in place does have work on the grid, I suspect there will be more). On the other hand keep in mind that most people during the week will be charging their cars at home, most trips are less than 30 miles and people will recharge at home. Home chargers are 40 amp/4kw, and they often charge at night when electrical demand is way less.
Something to think about, I saw this pretty good you tube channel on electric cars, and he cited some studies on electric vehicle use and carbon/mile output. Gas and Diesel cars, on a per mile basis, put out significantly more carbon emissions then if you look at the equivalent with EVs. Even in a state like West Virginia, that gets most of its power from Coal, the net carbon/mile is significantly less than burning gasoline or oil (and yes, electric tech also has greenhouse issues with producing the lithium they use, if you look at the lifecycle there is carbon emissions from mining it, shipping it etc). However, so do gasoline and oil, oil drilling releases methane and natural gas that is burned off, there is carbon impact refining gasoline, and then it needs to be transported (with diesel powered trucks and trains).
Right now I doubt batteries would work with long distance trains, impractical without rapid charging capability. Commuter lines because they are relatively short lengths, and have access to strong power grids, might make sense if they can work out the details. I am not sure converting existing engines will work out well and quite honestly, I think this is more about PR, showing they are doing something. I do know there is newer technology coming, batteries that have higher densities than lithium and don't have the drawbacks (like needing anything from China), that can recharge relatively rapidly. It could be that some sort of fuel cells work better (not a fan of H2 based cells).
