Electric APUs Could Stop Idling Trucks from Wasting 1.2B Gals. of Fuel Annually | Hacker News Reader

Electric APUs Could Stop Idling Trucks from Wasting 1.2B Gals. of Fuel Annually

earthandindustry.com

19 pointssprinkle7 comments

A relative is a long-haul trucker. The issue is weight and reliability.

There are maximum weight limits, which is why you see a lot of aluminum truck trailers - they weigh less. This will add to weight. Plus it must be reliable, any repair issues eat into the time when the truck could be on the road earning its keep.

FWIW this relative has boycotted California and the Northeast states (anything farther into New England than PA); they are too truck-unfriendly from his point of view (troopers hand out tickets for minor infractions strictly for revenue purposes, not many good truck stops). He trucks from PA to TX and back.

Not mentioned is that there is also a push to replace the small diesel engines that run the refrigeration unit on "reefer" trailers, yet another expense and a worry in terms of reliability (if the unit fails, the entire shipment can be spoiled).

Has anything practical come of other recent "innovation stories"? I recall reading a few years ago about hydrogen injection from electrolyzed water -- supposedly, it was already commercialized and being deployed -- including as a relatively inexpensive, after-market retrofit -- at least in limited measure. Also, a team at UW in Madison has been cranking out interesting engine design revisions, including IIRC one or more employing supplemental gasoline injection to improve burn efficiency (a small amount of gasoline, allowing a small tank's worth to last... several weeks, IIRC).

These stories crop up, and then seemingly fade away. Are fleets actually seeing any of this, yet -- if you or your relative have any perspective on this? If not, sorry to trouble you -- hope you don't mind the question.

Not a problem. I have not heard of any of these technologies being used in the field. The only thing I have seen in diesel tech is a pressurized fuel system which is only an incremental improvement.

Truckers are very conservative in their upgrades, remember that a truck has to haul up to 120,000 lbs (total weight), and has to last for anywhere between 500K and 1 million miles between significant rebuilds of any major piece such as transmission, engine, etc.

On top of that, there is a patchwork of taxes, Federal regulations, etc. that change on a yearly basis.

And trucking is very competitive and cut-throat, basically a low-margin business to be in. Low margins mean cost-cutting and no experimentation, so no one will test these new ideas unless they are paid to do so.

(Each 18-wheeler used full time pays fuel and excise taxes of approximately $20K just for the fuel and taxes alone, not including the income taxes paid by the driver and the taxes on profits by the corporate owner; so there are lots of fixed costs to cover before anyone makes any money.)

This is far more important than people driving Priuses. Making a tiny slice of the gas use / CO2 emissions pie smaller has a very small maximum benefit (switching from a Corolla to a Prius is noise in comparison to the 18 wheeler driving next to you on the highway), to get serious results you need to target the big slices. Now that we're starting to get the technology to do so perhaps we'll see some sizable improvements in the near future.

Long-haul truckers (and fleets) are probably the most fuel-use conscious drivers out there, so this kind of technology should be rapidly adopted. There are radio call in-shows catering to truckers where they discuss slight improvements in fuel economy due to tire tread pattern and wear, paints, fuel additives, aerodynamic optimizations, etc.

I don't get it... If they are electric, how do they charge them back up?

The batteries are charged from the main Diesel engine, but it's still more efficient, even with the conversion losses, due to load variation through time.

The issue is that the energy needed for the "hotel load" for the truck to run air conditioning, TV, etc. is very small compared to the size of the Diesel main engine (which is sized for propulsion, especially acceleration and going up a grade). Diesel engines use a roughly constant amount of fuel up to maybe 25-50% load, and then increase specific fuel use fairly slowly up to the efficient design level (which is probably highway cruise for most truck engines), and then increase specific fuel use much more quickly to peak power. (this depends a lot on the engine, and turbo/supercharged engines can have a wider band of efficiency)

By using an electric battery, and then charging it during normal use of the truck on-road, you change from a long duration inefficient use of the main engine, to a slight increase in power used during cruise (and it's a load which can be shut off instantly -- so you could run the charger during low-stress cruise, keeping the truck at maximum efficiency, or even run it entirely on regenerative braking in a future generation of the product).

Another option would be keeping a small Diesel APU on the truck to run rather than idling the main engine, but there are other benefits (noise, environmental) to the electric system. Given the right charging

The main penalty here is cost/complexity/weight of the system (which adds to fuel costs), but long-haul truckers pretty much sleep in their trucks every day, so it looks like it pays for itself quickly.

The other main system I've seen is "IdleAir" -- it's electricity, internet, and HVAC delivered by a flexible conduit into the truck. A central system at a truck stop provides it to all the trucks.

When I go on road trips (in a car), I've often wished for something similar -- I take breaks from driving every 2-4h, and sometimes to sleep overnight in rest stops, and being able to plug in and get power/internet/hvac without idling my car would be great. In some climates it's ok to sleep in a car without running HVAC, but in 130F sunlight, or -40F cold, that's not really an option.

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