At the end of my last post I said something to the effect that while I had just said pretty much all I had to say on the subject of diesel fuel, comments from my readers might spark something further. Indeed they have, and at least two of those ideas from the comments section are worth sharing here with the rest of my readers.
Battery Powered Tractor Trailers (EV Semis)
There has been a lot in the news lately about battery powered electric trucks suitable for long distance hauling of heavy loads, following the release of Tesla's prototypes of such a vehicle.
One reader on Facebook was outraged that I wasn't sufficiently impressed by Tesla's "achievement", but in the context of this blog whether disruptions in cargo transport are caused by problems with the supply of diesel fuel or problems with the supply of electricity (needed to charge batteries for electric trucks) is of little importance. We are going to experience both those problems, in any case, as collapse progresses.
Concerns about climate change, more than shortages of diesel fuel, are probably the driving force behind the interest in battery powered transport technology. In order to do something about climate change we do need to stop burning fossil fuels. The alternatives to fossil fuels—nuclear, wind, solar, etc.—all produce energy in the form of electricity, but electricity only accounts for about 20% of the energy we use. We need to find ways to use electricity where we now use coal, oil or natural gas. In the U.S., the trucking industry alone contributes about 23% of total greenhouse gas emissions, so it would seem that switching to electric trucks would make a big difference.
I am not at all convinced that this is even possible, or that it is such a good idea in any case. But I must admit that I just can't resist talking a little more about whether or not battery powered semi trucks are feasible and/or economically viable. Specifically, can Tesla battery powered truck do what they claims, or are they just more of the sort of marketing hype we've grown used to seeing from Elon Musk.
In an effort to become more informed on this subject, I did some googling and read a few articles, which I've listed below, along with the size of battery that each is guessing at for the Tesla trucks:
- Tesla—Semi. The people at Tesla claim their truck's energy consumption is less than 2 kWh per mile.
- Given the laws of physics, can the Tesla Semi really go 500 miles, and what will the price be? Alice Friedemann, at the Energy Skeptic blog, reckons a 30,000 lb. battery would be needed. Some of her realistic/pessimistic assumptions appear to account for this being the heaviest battery estimated by any of the people on this list.
- Key Specs on Tesla’s Electric Semi-Truck Still Secret. Jerry Hirsch at trucks.com figures on a 700 kWh,10,000 lb. battery.
- In The Truth About The Tesla Semi-Truck, in which the people at the You Tube channel Real Engineering say 900-1000 kWh would be needed for a 500 mile range, requiring a battery weighing 17,380 lbs., costing about $180,000
- You might also want to read Tesla's Quest for Better Batteries, wherein Real Engineer explain how he believes Tesla may be able to increase the energy density of their lithium ion batteries up to 300Wh/kg in the future
- Why Tesla’s Electric Semi Truck Is the Toughest Thing Musk Has Attempted Yet, according to Julia Pyper at Green Tech Media
- Tesla’s Newest Promises Break the Laws of Batteries, according to Tom Randall and John Lippert at Bloomberg, who talk about an 800 kWh battery, weighing more than 10,000 pounds and costing more than $100,000.
- Electric trucks like the Tesla Semi are 'pointless both economically and ecologically,' according to vehicle-tech experts at Business Insider.
There certainly isn't a lot of agreement among these people. A lot of that has to do with the fact that they are all talking about slightly different things and making somewhat different assumptions. Picking and choosing what seems to make sense from among these different analyses, here's what seems reasonable to me:
The kind of truck we're talking about is a "semi truck", "eighteen wheeler" or where I grew up a "tractor-trailer". Regulation wise this is a class 8 truck, and it can have a maximum weight, including payload, of up to 80,000 lbs.
Diesel trucks have an empty weight of 31,000 to 37,000 lbs, including the tractor with engine and fuel, and the trailer, leaving a payload weight of 43,000 lbs to 49,000 lbs. These trucks carry as much as 300 gallons of fuel, for a range of over 2000 miles. Regulations limit how long truck drivers can work in one stretch, so the argument is made that an electric truck with a range of 500 miles and a quick charge capability could compete with diesel trucks. I don't know about that—many of the truck drivers I know work in teams and have a sleeper cab so they can cover a lot more than 500 miles without making lengthy stops.
Diesel trucks consume 3.5 to 5.3 kWh per mile, while Tesla claims their semi will consume under 2 kWh per mile. While some of this phenomenal performance can be chalked up to reductions in drag, I suspect some of it may also be attributed to optimism and marketing hype.
That's about all Tesla is saying. They aren't telling us what the truck weights empty or what the battery weighs. We can make some intelligent guesses, though.
Using Tesla's optimistic numbers, and accepting that a 500 miles range is sufficient, at 2 kWh per mile, you need a 1000 kWh battery. Lithium ion batteries have an energy density from 100 to 265 Wh/kg. I think it's fair to assume that Tesla is using a battery at the upper end of that range. So a 1000 kWh battery would weight at least 8300 lbs.
What might their empty truck weigh? Take the lower end of the weight range for diesel powered semis (31,000 lbs.), subtract 4000 lbs for the engine and 2000 lb. for the diesel fuel, and you get 25,000 lbs. Add in the 8300 lb battery, and this gives them a total empty weight of 33,3000 lbs and a payload of 46,700 lbs.
Using a more healthy skepticism, we can estimate a 30,000 lb. battery and 30,000 lb. for the truck and trailer. That leaves us with only 20,000 lbs of payload. I expect the truth will turn out to be somewhere between those extremes.
In and of itself the Tesla truck appears to be technically feasible for runs of 500 miles or less. But just because something is technologically feasible doesn't mean it's economically practical, or even a good idea in any number of other ways.
All these calculations are based on trucks running on level roads. Hilly roads can use up quite a bit more power, even using regenerative braking when going downhill. The same can be said of stop and go traffic in cities. And these are conditions that real trucks have to cope with.
If we widen our horizon on the technical front just a bit, we can see another problem. Tesla says they'll be setting up a network of "super" charging stations which can charge a flat battery up to 80% charge in 30 minutes. It's pretty easy to see that there is a problem with this. It takes over two megawatts of power to charge a battery at that rate and a truck stop would probably need several such chargers. Current truck stops aren't equipped with anything like that heavy duty a power supply, and the power company would have to install new lines and substations to supply this load. While that is technically possible (though expensive) it would certainly add an additional source of stress to an already shaky power grid.
It's also important to remember that electric vehicles only reduce greenhouse gas emissions if the power used to charge those batteries is in itself "green". Currently, in many areas where power is generated using fossil fuels, this is just not the case. And as things stand at the moment we are adding renewables to the generation mix at a very low rate.
What about the economic outlook?all link to last post
A new diesel tractor usually ranges from $130,000 to $180,000. New trailers usually range from $30,000 to $80,000. Tesla quotes a base price $180,000 and a "Founders Series price" of $200,000. It is unclear if they are talking about just the tractor, or the combined unit of tractor and trailer. If it is the former, then they are well beyond the upper end of the cost range for a diesel truck. If it's the latter, then their price is more competitive. But batteries aren't cheap even if, like Tesla, you make your own. I can't help wondering what their profit (or perhaps loss) margin really is. At some point Tesla is going to have to start making money, or go out of business.
They also claim payback in two years based on the diesel fuel you wouldn't be buying, and a price for electricity at their charging stations of 7 cents per kWh. That's less than power costs in most areas, so once again I am left wondering how this can be a viable business proposition for Tesla.
Battery longevity is always a concern for electric vehicles. As batteries age, they can store less power, shortening the range of the vehicle. And if you have to replace the battery before the truck is worn out, it would add significantly to the lifetime cost.
All this analysis leaves me uncertain about the viability of battery powered trucks, and that takes me back to my original observation: it doesn't really matter much whether shipping is interrupted by shortages in diesel fuel or by interruptions to the power grid. In either case, the results will be similar. And it's those results that we need to be prepared for.
Horses vs Bio-Diesel
I put a link on the Collapse sub-Reddit to my recent blog post "Responding to Collapse Part 15: shortages of diesel fuel". This sparked a discussion on the merits of bio-diesel, and a much higher quality discussion than I have come to expect on Reddit.
I have no doubt that powering the currently existing fleet of diesel trucks, locomotives and ships with biodiesel in order to continue on with BAU (business as usual) would not be feasible. It would take up so much of the available agricultural land to produce the vegetable oil to be converted to bio-diesel that while the vehicles might be happy, the human race would be left starving. The EROEI of bio-diesel is, after all, only around 5.
Even using biodiesel just to power agricultural equipment in an attempt to feed 7 billion plus people wouldn't be feasible for the same reason—just too much land would have to be planted to oil seed instead of food for people. But I think there is something to be said for the idea of growing oil seed to make biodiesel to power agricultural equipment in the areas surrounding the small remote towns I have been talking about throughout this series of posts. The population density of such areas is much lower and there is more land to go around.
The real question is which is more feasible: tractors powered by bio-diesel or horses (and other draught animals) powered by hay and grain.
I did some googling and found a good article in Low tech Magazine discussing that very issue. The author reckons that on a farm worked with horses about 11 percent of the acreage would have to be used for growing the crops used to feed the horses. A farm worked with tractors burning bio-diesel would have to set aside about 26 percent of its area to grow oilseeds to be converted to bio-diesel for the tractors.
Not surprisingly, this would seem to indicate that farms powered by diesel fuel use about 2.5 times as much energy as farms powered by horses. When cheap diesel fuel refined from petroleum is available, this extra energy provides a couple of benefits. One, the land used to grow horse feed is freed up to grow other crops. Two, the powered equipment reduces the amount of human labour required. Much of the success of modern farms, be it conventional or organic, is based on this.
In a post fossil fuel, post collapse world, where the energy used to power machinery has to be produced on the farm or at least in the local area, those advantages disappear. Initially, though, I think bio-diesel does have some merit. The thing is that there aren't very many draft horses around today and it will take some years to breed up and train the population of horses that will be required. The diesel burning equipment, however, already exists and the main thing needed to keep it running is to grow the oil seed (probably canola in the area where I live) and set up the equipment required to press the oil from the oilseed and convert it to bio-diesel.
Eventually, of course, the existing diesel powered equipment will wear out beyond the ability of the local foundry/forge/machine shop to repair it, and it will have to be replaced by horses.
A breeding program for draft horses seems quite doable, as does a development program for horse drawn/powered equipment using existing equipment adapted for horses or new equipment built with village level technology using scrap metal and locally sourced wood.
The bio-diesel enthusiasts make producing bio-diesel sound fairly easy, but they are thinking in terms of ordering whatever they need from BAU supply chains. Making everything required from locally available materials using village level technology will be more of a challenge. Still, with some advance preparation while the supply chains are still running, it should be doable. Such a biodiesel program doesn't need to be long term sustainable—it only has to work for a few years until the horses are ready.
Existing diesel engines can't use straight vegetable oil (SVO), so some processing is required to turn SVO into bio-diesel. Here a rough list of what is needed:
- seed for the first crop of oilseed
- planting and harvesting equipment
- mechanical presses to get the oil out of the oil seed
- the chemicals required in the process to turn the vegetable oil into biodiesel:
- a caustic (sodium hydroxide, potassium hydroxide or calcium hydroxide)
- an alcohol (methanol or ethanol),
(there are reasonably low tech processes to produce these from locally available materials, although it would sure help to have someone involved who has studied up on the relevant chemistry)
- the vessels, piping, valves, pumps, instrumentation and so forth needed to do the processing
The alternative to bio-diesel would be to use a lot more human muscle power in local agriculture until it can be replaced, or at least augmented, by horses. This should provide incentive to get a bio-diesel program set up in advance.
Here are some sources of information on bio-diesel:
Addendum to the Addendum
A number of people in various forums have commented about the virtues of oxen. I can't say much about that from personal experience. There was an ox yoke handing in a shed on the farm where I grew up—it hadn't been used in many decades. I think I asked dad about oxen at least once, and it was clear he much preferred horses. Clearly, oxen can do the job, and int he early days of a post collapse world, there will be many more cattle around than draught horses. So it would make sense to train some of them as oxen. Especially if the bio-diesel thing isn't working out too well.
- Biodiesel Production Principles and Processes
- Make Biodiesel— Learn How to Make Your Own Biodiesel at Home
Well, I think that's really it now for my discussion of diesel fuel. After the new year, my next post will finish off this series with a look at coping with shortages of money.
Links to the rest of this series of posts, Preparing for (Responding to) Collapse:
- Preparing for Collapse, A Few Rants, Wednesday, 25 July 2018
- Responding to collapse, Part 2: Climate Change, Saturday, 15 September 2018
- Responding to collapse, Part 3: Declining Surplus Energy, Friday, 26 October 2018
- Responding to collapse, Part 4: getting out of the city, Wednesday, 21 November 2018
- Responding to collapse, Part 5: finding a small town, Friday, 28 December 2018
- Responding to Collapse, Part 6: finding a small town, continued, Monday, 28 January 2019
- Responding to Collapse, Part 7: A Team Sport Monday, 18 March 2019
- Responding to Collapse, Part 8: Pitfalls and Practicalities of that Team Sport Tuesday, 26 March 2019
- Responding to Collapse, Part 9: Getting Prepared, Part 1, Thursday, June 13, 2019
- Responding to Collapse, Part 10: the future of the power grid, Wednesday, July 17, 2019
- Responding to Collapse, Part 11: Coping with power outages, the basics, Sunday, August 25, 2019
- Responding to Collapse, Part 12: Coping with longer power outages, Thursday, September 19, 2019
- Responding to Collapse, Part 13: keeping the lights on when the grid goes down forever, Wednesday, 16 October 2019
- Responding to Collapse, Part 14: adapting to life without the grid, Tuesday, 29 October 2019
- Responding to Collapse, Part 15: shortages of diesel fuel, Wednesday, 27 November 2019
- Responding to Collapse, Part 15—Addendum, Saturday, 21 December 2019