Life Cycle Environmental Impact

[SailingHarmonie]

Just for discussion and thought. Things are always more complex in the real world than politicians and activists of any stripe present.

As an engineer, I know how notoriously difficult any kind of overall life cycle analysis can be, especially environmental ones. It is very complex to sort out the real differences between two alternatives when you have to trace everything back to the mine to be sure you have it right.

The analysis frequently result in conclusions that are contrary to intuition, and to what we are presented as "obvious" in the media. Just as an example, every comprehensive and well done study comes to the same conclusion in the automobile industry: The lowest impact vehicles are NOT fully electric, but are the plug-in hybrids. Although a HUGE difference in results can be found by small tweaks of the assumptions around usage patterns and lifespans.

This study of the relative impact of electric propulsion in boats is not new (but is new to me).

As an engineer, the results make intuitive sense to me. Resource inputs to BUILD an electric powered boat are significantly larger than a hydrocarbon fueled one. The hull, drive engine, control systems, etc. are all essentially the same. The biggest difference is the fuel tank is replaced with batteries. Pretty obvious that batteries have a huge resource input compared to a fuel tank. So the electric boat starts out with a significant environmental deficit. The ideal is that it's fuel is totally green and it doesn't make any more CO2 ever, so it eventually turns into the green option if it is used enough. That turns out to not be true.

Now comes the REALY hard part. What is the environmental impact of the energy source that goes INTO the fuel tank or batteries? What percentage of the electricity is actually "green"? Right now the answer for the marginal impact of a new boat is (in most places): Zero % green.

If you are consuming more electricity from the grid then--for the foreseeable future--that extra energy is coming from fossil fuel. Until renewables can actually be in surplus, and are sitting idle waiting for new loads, any increase in energy demand comes from additional fossil fuel.

For liquid fuel, it is extremely complex to figure out the actual carbon footprint, there are so many assumptions that hugely impact the result. While the conclusions of this study are that "bio-fules" are best, I have to admit, I am not a fan. The amount of land that would have to be cleared to grow bio-fuels is beyond prohibitive. They are now, and always will be, a tiny niche of the energy picture.

[Kettlewell]

Plus, for many of us cruising sailors it is virtually impossible to plug in often enough to be able to charge up, meaning we would have to utilize solar and wind or other technologies to charge the huge batteries required. Even if I could find a slip to rent for the season (highly doubtful) in New England, I would be looking at paying something like $6000 and up for the privilege. Who knows what they would charge for electricity if everyone started charging big boat batteries for propulsion. Most cruising sailboats around here are stored on mooring balls. When cruising I almost never go into a dock--if I had to do it every day to charge up I might as well quit cruising because spaces are usually unavailable.

[wholybee]

Can you refer me to some of the studies that show plug-in hybrids as having less impact than 100% electric? I am curious what they were using as a use case, or the percentage of electricity that is renewable.

If almost all of your driving is very short and you rarely use the ICE engine, then of course a hybrid will have very low total footprint. OTOH, my last car (I currently don't drive) was a hybrid, and the 40mpg that I got was great, but could also be achieved with a pure ICE engine.

The local area is also very important. There are areas in the US and around the world were all or nearly all energy is renewable. And also areas where very little is. I think it is important to recognize this moving target. It isn't fair to say one type of car has less impact that others, because that could change in a few months. So we should be looking at the changes that are coming, and plan for the future.