[ I’ve written many articles on why trucks are not likely to ever run on batteries or overhead catenary wires (and why a 100% renewable electric grid is probably not possible). Nor can trucks run on biofuels, liquefied coal, natural gas, or hydrogen. This is covered in my book “When trucks stop running”. I also explain why oil is difficult to replace (an overview can be found in post “Energy Overview. Oil is butter-fried-steak wrapped in bacon. Alternative Energy is lettuce“). Also see 1) Decline, Transportation, Trucks and under the Energy menu, there are many posts on batteries, biofuels, coal, electric grid, energy storage, hydrogen, natural gas, solar, and wind.
This post is mainly about off-road vehicles, especially trucks, which are essential for infrastructure, which is just as critical as on-road trucks are for maintaining supply chains, which would stop if roads and bridges weren’t repaired by off-road trucks.
This post is also about how amazing diesel engines are. If you’re a die-hard optimist, I hope you’ll at least come away with how daunting it would be to replace diesel engines with anything else. And don’t forget how short on time we are to do this — 90% of our oil, conventional oil, peaked world-wide in 2005.
Off-road trucks and equipment present an even larger challenge than on-road trucks to converting to another propulsion mode. We can’t electrify them by stringing overhead wires across 300 million acres of farmland, along thousands of miles of transmission lines, tens of thousands of miles of logging roads, or most construction and mining sites, which can also be far from the electric grid, or where there isn’t enough power in that part of the grid. Nor could you add overhead wires over all the nations the U.S. military would like to invade with tanks.
Batteries won’t work. They are too heavy for on-road trucks, and off-road vehicles usually weigh and require even more power. The reason diesel fuel is so essential is that it is 100 to 500 times more energy dense than batteries by weight or volume, and large off-road trucks need enormous amounts of power to move across rough terrain while also performing some other high-powered task.
It’s also hard to replace off road trucks because they’re so specialized, with nearly each of them custom-made for a specific purpose. This lack of mass production makes it harder to transfer technology because it costs a great deal more to custom-build.
Whatever energy source is used to move trucks has to be POWERful, enough to perform a given task, such as moving a 40,000 pound truck uphill. This can be determined by figuring out the power level to see if the energy flow will do the trick. And of course the distribution system must be adequate. Perhaps a truck that runs on CNG or LNG natural gas has enough power, but are the CNG/LNG filling stations along the entire route? Diesel is a highly concentrated energy, but trying to fly an airplane on burning straw is clearly an impossiblility, the straw storage area would be hundreds of times larger than an airplane.
There are good reasons trucks run on diesel, which will be very hard to replace.
Alice Friedemann www.energyskeptic.com author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report ]
DTF. June 2003. Diesel-Powered Machines and Equipment: Essential Uses, Economic Importance and Environmental Performance. Diesel Technology Forum. 39 pages.
The diesel engine is the backbone of the global economy because it is the most efficient internal combustion engine – producing more power and using less fuel than other engines.
Of course, an electric motor can be very powerful, but as discussed above, trucks are too heavy to be powered by batteries, off-road can’t be electrified with millions of miles of catenary wires, and on-road catenary is so expensive the number of miles would be limited as well.
The off-road industries that rely on diesel must have a source of heavy-duty mechanical power that is mobile or portable. Other sources of industrial power, such as the electricity grid and steam boilers, are simply not adaptable to mobile applications or are not portable to remote locations. Only internal combustion engines can meet this demand for efficient mobile/ portable heavy-duty power.
Diesel engines have many applications and engine types, making technology transfer difficult and expensive
Non-road diesel engines serve so many different functions that they require a wide range of engine types, sizes, designs, and configurations, from 10 to 100,000 horsepower. This specialization makes technology and emission improvement transfers much harder. Most on-road trucks are custom built as well.
Diesel engines offer more power
Diesels produce more drive force at lower engine speeds. This superior drive force is the result of the diesel engine combustion process, known as “compression ignition.” Compression ignition produces superior combustion force in the cylinder, which in turn provides more power or “torque.
High torque and power at low speeds is particularly critical in non-road applications. Tractors, bulldozers and backhoes must have enough power to both lift, push, pull, and dump as well as propel very heavy machines across rough surfaces and steep terrain.
Diesel engines have better energy efficiency
Although diesel engines and spark-ignition gasoline engines have equivalent power output characteristics, diesel engines will consume 25 to 35% less fuel doing the same work because of the greater efficiency of compression ignition and the higher energy content of diesel fuel (11% more than gasline, 67% more than LNG, and 250% more than CNG at 3600 psi). This is important for off road vehicles so that they don’t have to refuel often, especially in remote locations.
Diesel efficiency: combustion cycle and fuel energy density
Diesel’s compression ignition process results in greater thermal efficiency – more of the fuel’s chemical energy is harnessed as mechanical energy. Diesel holds this advantage over any spark-ignited engine, including gasoline, CNG, LNG, and propane (“LPG”). Like gasoline engines, these other spark ignition engines are less fuel-efficient because they burn fuel at lower temperatures under lower compression.
Diesel’s combustion cycle is also more efficient than a spark ignition engine’s because it does not rely on a throttle plate to control power which increases “pumping losses,” reducing efficiency. At lower power the throttle plate in a spark ignition engine’s air intake is partially or completely closed, creating a vacuum in the intake manifold. The cylinders must pump against the vacuum to draw air. Considerable work is wasted by the engine just to draw in air for combustion at low/closed throttle positions. A gasoline engine is at its highest efficiency at high power with open throttle even though most of its life is spent at low throttle. A diesel engine has no throttle plate. The power output is controlled by the amount of fuel injected and pumping losses are therefore much lower.
Natural gas is not a good substitute
The low energy density of natural gas can be partially made up for by using larger fuel tanks, but the added weight of the tanks lowers fuel economy, and the size of the tanks may be entirely impractical in many types of non-road equipment.
Diesel engines essential for very large applications
Spark ignition engines cannot substitute for diesel engines used in applications requiring very high power output at low speeds, because most spark ignition engines cannot perform above 400 horsepower, and run much hotter, requiring more cooling than diesel. This is one of the reasons spark ignition engines can’t be as large as diesel engines, which causes “detonation” or “knock,” from the spontaneous ignition of fuel in the cylinder at high cylinder temperatures.
The fact that diesels produce less wasted heat makes them more suitable for very large applications, like ocean-going ships, railroad locomotives and earth movers. One of the biggest issues in designing large engines is the need to provide cooling systems to prevent overheating. This is a major challenge when dealing with the heat produced in very large combustion chambers. Because diesels waste less energy as heat, they place less demand on cooling systems than spark ignition engines. This permits diesels to be scaled up to very large sizes — diesel engines in some applications have cylinders as large as three feet in diameter.
Durability and Reliability
Diesel engines are legendary for their durability and reliability. Diesels can go far more miles than gas engines before rebuilding is necessary, and also are easier to rebuild. Heavy-duty off-road truck engines usually last for 20 to 30 years, and rail locomotives even longer – often more than 50 years.
Diesel fuels are less volatile and safer to store and handle than gasoline. It also ignites at a much higher temperature than gasoline or natural gas, making it less likely to ignite if spilled or released in an accident. Diesel is also safer because it doesn’t require pressurized vessels like CNG. High pressure greatly increases the risk of leaks during loading, unloading and storage.
Off-road applications of diesel engines
Farms and ranches use diesel to power 66% of all agricultural equipment — almost $19 billion worth of tractors, combines, irrigation pumps and other farm equipment. Back in 1945, it took 25 million people, 17.5% of the population to farm America’s roughly 300 million acres of farmland. By 1997, America had fewer than two million farms and less than a million individuals who identified farming as their principal occupation. The average size of a farm had grown from 195 to 487 acres. The number of tractors grew by 3.9 million—an average of about 2 per farm, and 700,000 farms had either three tractors, and another 300,000 farms had four or more tractors. In 1983, the last year for which this data is available, each tractor averaged 66 horsepower. By 1997 a million of the 3.9 million tractors had a power output of more than 100 horsepower.
Examples of agricultural diesel vehicles & equipment:
- Tractors: wheel tractor-scrapers, rotary cutters, skid steer loaders, loaders, sprayers, utility tractors, row crop tractors
- Balers: Bale handlers, round/square balers, choppers, mowers, forage harvesters, shredders, windrowers
- Planters & Seeders: air seeder, drills, unit planter
- Other diesel equipment: Hoes, plows, generators, milking machines, grinders, cotton pickers/strippers, combines, irrigation sets/pumps, swather, tillers
Forestry equipment :
- Log handling (log loaders, knuckleboom loader, track harvester)
- Skidders (wheel and track)
- Fellers/Bunchers: track feller bunchers, wheel feller, bunchers felling heads, cut-to-length, harvesters and forwarders
- Firefighting & bulldozers, backhoes are key tools in suppression and fighting of forest fires
Nearly 100% of off-road construction equipment —$17 billion worth — is diesel-powered.
The latest economic census data show that almost 656,000 entities were engaged in construction in 1997, employing 5.7 million people, purchasing $241 billion in materials, components, supplies and fuels. Much of the diesel-powered equipment used in construction is classified as “off-road.” Over 440,000 diesel-powered off-road equipment was produced in the U.S. between 1991 and 1995. 10
Examples of diesel construction applications:
- Dozers: Rubber-Tired Dozers, Wheel Dozers, Telehandlers, Landfill Compactors, Pipelayers
- Loaders: Rubber-Tired Loaders, Skid Steer Loaders, Track-Type Loaders, Track Loaders, Multi-Terrain Loaders, Wheel Loaders, Backhoe Loaders, Integrated Toolcarriers
- Excavation: Wheel Material Handlers, Excavators, Backhoes, Mass Excavators, Demolition Excavators, Wheel Excavators, Front Shovels
- Pavers/Paving Equipment: Cold Planers, Asphalt Paving Equipment, Pneumatic Compactors,
- Compactors: Asphalt Compactors, Vibratory Soil Compactors, Motor Graders
- Other: Road Reclaimers, Soil Stabilizers
Bores/Drill Rigs, Cement Mixers, Off-Highway Trucks, Off-Highway Tractors, Scrapers, Trenchers, Plate Compactors, Concrete/Industrial Saws, Signal Boards, Generator Sets, Crushing Equipment, Welders
Diesel power accounts for 72% of the power used in mining. The bituminous coal and lignite surface mining segment of the industry relies on off-road trucks and heavy earth-moving equipment powered. The oil and gas production segment of the industry requires diesel power for 85% of its drilling operations and more than half of its support operations. 13 The largest rubber-tired, diesel-powered equipment is to be found in mining—off-road trucks with engines of over 2,500 horsepower, capable of hauling over 300 tons per load [my note: tar sand trucks carry even more than this now].
Mining equipment examples:
- Underground Mining Equipment: Articulated trucks, load haul dump trucks
- Heavy earth-moving equipment: Dozers, loaders, excavators
- Other: off-road trucks, generators, pressure washers, cranes, forklifts
One of the economic sectors most heavily reliant on diesel engines is non-road freight transportation. Diesel power moves about 94% of the nation’s freight ton-miles.17 While much of this freight is moved by diesel-powered highway trucks, non-road modes of transportation are also critical to freight transport. In these non-road modes, which include railroads, marine shipping, and intermodal movements, diesel is the exclusive or dominant source of power.
Marine Freight Transport. The engines that power bulk carriers and container ships are the largest diesel engines made. They can generate over 130,000 horsepower, have as many as 18 cylinders, and stand three to four stories high. 22 According to the U.S. Army Corps of Engineers, there are over 5,000 towboats in the U.S. towboat fleet. These towboats range between 1,800 and 10,500 horsepower, and generate a total of 9.4 million horsepower. 26
Public Safety & Homeland Security: When primary power systems fail, emergency back-up diesel generators are the only source that can provide immediate, reliable and full strength power. Construction equipment is required to assure safe operation of the nation’s utilities, install public drinking water and sewer systems as well as fiber optic and telecommunications cables. And when disaster strikes, this same equipment plays a vital role in rescue, recovery and clean-up efforts, helping to rescue trapped victims, and remove debris after hurricanes, tornadoes, ice storms and other natural disasters.
Military: Diesel engines propel a wide variety of weapons systems and power auxiliary equipment used by the military such as generators, compressors, pumps and cranes. The diesel engine’s superior fuel economy means that equipment can travel farther than other fuels. Since the military must transport large amounts of fuel, this greater fuel efficiency cuts logistical support costs and extends the military’s striking range. Diesel’s fuel relative safety reduces the risk of explosion if vehicles and equipment are hit during combat. If need be diesel engines can burn a wider range of fuels than gasoline engines.
Military diesel equipment examples:
- Most of the amphibious force vessels: Vehicles transporting troops, equipment, material to mission sites
- Auxiliary ships: combat support vessels
- Military Sealift Command: All oilers and fleet ocean tugs, 50% of dry cargo ships, combat stores, etc.
- Navy Sealift Force: Tanker and Roll-on Roll-off ships
U.S. Coast Guard
- All high-endurance cutters are also powered by diesel engines; all non-high endurance cutters are propelled solely by diesel
- Ice-breakers propelled by diesel-electric systems
U.S. Army and Marines
- Most armor and self-propelled artillery are diesel powered, with a wide range of uses and functions: M2/M3 Bradley armored personnel carriers, ambulances, mortar carriers, anti-aircraft gun carriers, missile launchers
- Tank destroyers, self-propelled guns and howitzers: M901, M109, M110
- Amphibious assault vehicles: LFTP7A1
- Almost all military vehicles and logistics systems: prime movers, heavy-equipment transporters, special attack vehicles, Humvees”
Off-road truck vehicles and equipment have diesel engines ranging from 10 to 3,000 Horsepower. On-highway diesel engines (i.e. class 8 long-haul trucks) typically range from 120 to 600 HP. Train locomotives use 6,000 horsepower.
Each off-road equipment application presents different mechanical and duty cycle demands on the diesel engine. This diversity of mechanical demands in turn requires a correspondingly wide range of different engine designs and configurations to power each different type of equipment. The operating requirements of off-road equipment subject these engines to a much more strenuous and varying set of demands and duty cycles than on-highway equipment. Most off-road equipment relies on their engines both to propel the vehicle and to operate attachments like buckets, blades and shovels. Off-road vehicle propulsion requires an engine capable of maintaining traction and maneuverability over a broad range of terrain profiles and physical conditions. Most off-road construction, mining and farming equipment also use engine-driven hydraulic pumps to power the attachments that do the lifting, pushing, drilling, pumping, loading and dumping that the equipment is designed to accomplish. These additional accessories create additional unique power demands on the engine that are not found in on-highway engines, where power is primarily used for propulsion.
Off-road engines are also subject to higher-temperature operating environments than on-highway engines. Unlike on-highway trucks, most off-road equipment runs at very low vehicle speeds. As a result, off-road engines must operate without the benefit of “ram air” for cooling. Ram air is the airflow over the engine and cooling system created by the forward motion of the vehicle itself, which for highway vehicles can be in excess of 65 miles per hour. Off-road vehicles are relatively stationary and rarely exceed 10 miles an hour during work operations. The lack of ram air, combined with the additional accessory loads, require off-road engine makers to install more elaborate cooling systems, which typically consume between 10-20 percent of total engine power output. 31
Because the same off-road engine model is frequently used in a variety of equipment applications, off-road engines also require a great deal of versatility within the same design. For example, a portable electric power generator may use the same engine as a front-end loader. But the two pieces of equipment will require the engine to perform over very different operating ranges and cycles. The engine in the electric power generator enjoys long periods of operation at constant speeds and steady loads, whereas that same engine installed in a front-end loader would be typically subjected to a much more challenging and variable duty cycle featuring frequent alterations between high engine speeds and loads, and periods of low-speed idling between tasks.
1 Willard W. Pullcrabek, Engineering Fundamentals of the Internal Combustion Engine, Prentice Hall, 1997. The temperature in the exhaust system of a typical compression ignition engine will average between 200° and 500°C, whereas the temperature in the exhaust system of a typical spark ignition engine will average 400° to 600° C, and will rise to about 900°C at maximum power. A full list of references can be found at the end of this report.
2 “Gross Domestic Product by Industry for 1999-2001,” Robert J. McCahill and Brian C. Moyer, at http://www.bea.gov/bea/an2.htm#GParticles
3 “Diesel Technology and the American Economy,” Charles River Associates, p. 55 (October 2000).
4 Statistical Abstract of the United States, 1999 edition, Table 738. 5 USDA, Economic Research Service, Natural Resources and Environment Division, Agricultural Resources and Environmental Indicators, “Production Inputs,” 1995, pp. 135–136. The data in this report include electricity in addition to liquid fuels. However, data on electricity use in agriculture ceased to be available after 1991. The data reported above are for liquid fuels—gasoline, diesel, and LP gas.
6 U.S. Department of Agriculture, 1997 Census of Agriculture, “Farm and Ranch Irrigation Survey.”
7 “Diesel Technology and the American Economy,” Charles River Associates, p. 55 (October 2000).
8 “Diesel Technology and the American Economy,” Charles River Associates, p. 27-28 (October 2000).
9 “Gross Domestic Product by Industry for 1999-2001,” Robert J. McCahill and Brian C. Moyer, at http:// www.bea.gov/bea/an2.htm#GParticles.
10 U.S. EPA, Final Regulatory Impact Analysis: Control of Emissions from Non-road Diesel Engines.
11 ICF Kaiser Consulting Group, “Off-Road Vehicle and Equipment: GHG Emissions and Mitigation Measures,” Table 8, p.18.
12 “Diesel Technology and the American Economy,” Charles River Associates, p. 55 (October 2000).
13 “Diesel Technology and the American Economy,” Charles River Associates, p. 31 (October 2000).
14 “Diesel Technology and the American Economy,” Charles River Associates, p. 28 (October 2000).
15 “Gross Domestic Product by Industry for 1999-2001,” Robert J. McCahill and Brian C. Moyer, at http:// www.bea.gov/bea/an2.htm#GParticles.
16 Calculation by CRA from 1997 Economic Census, Mining by Subsector.
17 “Diesel Technology and the American Economy,” Charles River Associates, p. 8 (October 2000). This figure includes freight transportation by trucks.
18 “Diesel Technology and the American Economy,” Charles River Associates, p. 12 (October 2000). Census statistics for 2002 are currently being prepared by the U.S. Census Bureau.
19 “The North American Railroad Industry,” Association of American Railroads, at http://www.aar.org/ AboutTheIndustry/AboutTheIndustry.asp.
20 “Economic Impact of U.S. Freight Railroads,” Association of American Railroads, at http://www.aar.org/ ViewContent.asp?Content_ID=296.
21 “Gross Domestic Product by Industry for 1999-2001,” Robert J. McCahill and Brian C. Moyer, at http:// www.bea.gov/bea/an2.htm#GParticles.
22 2002 Diesel and Gas Turbine Catalog
23 “Diesel Technology and the American Economy,” Charles River Associates, p. 16 (October 2000).
24 U.S. DOT, Maritime Trade and Transportation ’99, Table 1-16.
25 U.S. Maritime Administration, MARAD ’98, p. 39.
26 U.S. Army Corps of Engineers, Waterborne Transportation Lines of the United States, Calendar Year 1998, Vol. 1, Table 1.
27 Sierra Research, Inc., “Technical Support for Development of Airport Ground Support Equipment Emissions Reductions,” Prepared for Office of Mobile Sources, USEPA, Contract No. 68-C7-0051, December 31, 1998.
28 See, 40 C.F.R. Part 89 (Off-road); 40 C.F.R. Part 92 (Locomotives); 40 C.F.R. Part 94 (Commercial and Recreational Marine)
29 Engine Manufacturer’s Association’s Supplemental Comments on EPA NPRM For Motor Vehicle and Engine Compliance Program Fees (Docket No. A-2001-09), dated January 14, 2003
30 An extensive sampling of the diversity of diesel applications can be found in the U.S. EPA, “Final Regulatory Impact Analysis: Control of Emissions from Nonroad Diesel Engines,” EPA420-R-98-016, p.4, August 1998.
31 U.S. Department of Energy, Off-Highway Vehicle Technology Roadmap, December, 2001 (DOE/EE-0261) pp 30-31.
32 The only diesels not subject to federal emissions standards would be certain vehicles and engines manufactured pursuant to military vehicle regulatory exemptions.
33 EPA established emission standards for diesel locomotives that took effect in 2000. 63 Fed. Reg. 18978 (April 16, 1998) (codified at 40 C.F.R. pt. 92). Standards for large (>37 kW) marine engines will take effect in 2004. 64 Fed. Reg. 73300 (Dec. 29, 1999) (commercial marine); 67 Fed. Reg. 68242 (Nov. 8, 2002) (recreational marine) (to be codified at 40 C.F.R. pt. 94).
34 40 C.F.R. § 89.112, Table 1 (2001) (values in g/kW-hr have been converted to g/bhp-hr);U.S. EPA, “Final Regulatory Impact Analysis: Control of Emissions from Nonroad Diesel Engines,” EPA420-R-98-016, pp. 5-7, August 1998.
35 59 Fed. Reg. 31306 (June 17, 1994); 63 Fed. Reg. 56968 (Oct. 23, 1998).
36 30 C.F.R. pts. 7, 36, 56, 57, 70, and 75.
37 October 30, 2002, letter from EPA, Office of Policy Economics, and Innovation to Small Entity Representatives, Section B Description of Rulemaking.
38 The Diesel Technology Forum maintains a searchable database containing project-specific details of various diesel retrofit programs across the country. See www.dieselforum.org/retrofit/activitymatrix.asp.
39 “Retrofitting Emission Controls on Diesel-Powered Vehicles,” Manufacturers of Emission Controls Association, March 2002, available at: www.meca.org/dieselretrofitwp.PDF.
40 “Retrofitting Emission Controls on Diesel-Powered Vehicles,” Manufacturers of Emission Controls Association, March 2002, available at: www.meca.org/dieselretrofitwp.PDF.
41 “Retrofitting Emission Controls on Diesel-Powered Vehicles,” Manufacturers of Emission Controls Association, March 2002, available at: www.meca.org/dieselretrofitwp.PDF.
42 “Retrofitting Emission Controls on Diesel-Powered Vehicles,” Manufacturers of Emission Controls Association, March 2002, available at: www.meca.org/dieselretrofitwp.PDF.
43 “Retrofitting Emission Controls on Diesel-Powered Vehicles,” Manufacturers of Emission Controls Association, March 2002, available at: www.meca.org/dieselretrofitwp.PDF.
44 Alex Kasprak, Massachusetts Turnpike Authority, et al., “Emission Reduction Retrofit Program for Construction Equipment of the Central Artery/Tunnel Project,” Paper No. 206, Presented at the 94th Annual Conference of the Air and Waste Management Association, Orlando, Florida (June 2001).
46 Edward Kunce and Steven Lipman, Massachusetts Department of Environmental Protection, “Massachusetts Diesel Retrofit Program (MDRP),” Presented at the Innovative Technology/Aftermarket Retrofit Program Workshop, Houston, Texas (September 2000).
47 Alex Kasprak, Massachusetts Turnpike Authority, et al., “Emission Reduction Retrofit Program for Construction Equipment of the Central Artery/Tunnel Project,” Paper No. 206, Presented at the 94th Annual Conference of the Air and Waste Management Association, Orlando, Florida (June 2001).
48 Edward Kunce and Steven Lipman, Massachusetts Department of Environmental Protection, “Massachusetts Diesel Retrofit Program (MDRP),” Presented at the Innovative Technology/Aftermarket Retrofit Program Workshop, Houston, Texas (September 2000)