I worked on a lot of RR emissions analysis, looking at the economics and capacity of new technologies for locomotives, including funding work by Southwest Research Institute. Battery technology is improving, and some current hybrid locomotives do use large battery arrays, but as a reliable cost effective road locomotive technologies, I don't see either the range or economic viability, as realistic alternative battery "only" "road" locomotives.

I've also worked on several RR electrification studies, and for health standard criteria pollutants it was, on a "cost per ton" of emissions basis, a very expensive "high marginal cost" per ton reduction from current Tier III and IV diesel standards.

However, at some point, with a proper "carbon trading" system, and proper investment tax credits, using more things like CA's carbon funds, to achieve the most cost effective reductions in carbon emissions (as opposed to pissing it away on the CAHSRA fiasco), we should probably take another "long term" look at the cost benefit and proper funding/financing mechanisms to do RR electrification, for the "long term" CO2/GHG emission reductions it might provide.

And, as opposed to the "high cost" of relatively small changes in impacts on health criteria pollutants, in this new CO2/GHG calculation, we'd now have to include in that "cost-benefit" calculations for carbon reductions, the hundreds of billions in costs just to "harden" our coasts against sea level rise and increasing storm surge.

The costs of "hardening" our coasts against sea level rise includes things like the very "real cost" of the Del Mar bluffs LOSSAN relocation. And, it includes many other very costly things like the acquisition and restoration of the Gulf barrier islands, the cost of "raising" New Orleans, Mobile, Biloxi, Galveston, Corpus Christi, and other places that will be impacted by higher sea level and more intense storms. It includes things like the hundreds of miles of new sea walls, the dozens and dozens of storm gates to protect rivers and harbors from increased flood surge, the thousands of miles more of levee protected flood control, and on and on in real costs...

These things will be needed to protect just these coastal communities and economic assets from the real and measurable rising sea level rise we are measuring, and from the impacts of things like increased hurricane, cyclone, and flood damage from increased "energy" (and thus, storm "intensity") due to rising sea temperatures that we are actually measuring.... which are especially noticeable in "small" seas like the Gulf of Mexico.

What we don't want to do, is to waste the precious limited resources we do have to respond to this problem on useless, low emission reduction projects or schemes, like what we've seen with the carbon funds wasted on the CAHSRA fiasco.