Dr. Raj Shah, Dr. Steve Nitodas, Mr. Nicholas Douglas and Mr. Nathan Aragon
In its natural form, energy has contributed significantly to humanity’s progress over the years. However, due to an unchecked increase in pollution, new alternatives to fossil fuels need to be developed. Currently, new research into fuel additives, including those with nanotechnology, such as nanofluids, show promise in reducing pollution and offer sustainable fuel options. The purpose of this article is to explore how nanoparticles function as fuel additives for improving fuel efficiency and controlling pollution.
The impact of nanoparticles as fuel additives has shown serious improvements but also implications for the energy sector. The studied nanoparticles included several elements, such as zinc, aluminum, and boron metalloids. These nanoparticles were then emulsified with various fuels, primarily diesel, and used for testing in standard engines1. Fuels infused with nanoparticles show improved calorific value and cetane number of diesel and biodiesel fuel. However, viscosity, flash point and density of fuel can be slightly increased. In addition, the concentration of nano fluid additives must be kept under an upper limit to avoid higher CO emissions.
As for the efficiency of the engines, researchers found that nano-additives improve fuel and engine efficiency. Both brake specific fuel consumption (BSFC), which is the rate of fuel consumption per unit of power used, and brake thermal efficiency (BTE: how well an engine converts heat from fuel to mechanical energy) were improved by varying margins. For example, zinc oxide (ZnO) additives exhibited a decrease in BSFC from 0.278 and 0.272 kg/kWh, and an increase in BTE from 28.8 to 29.96 kg/kWh when the particle size doubled1. These results show promising evidence of efficient engines with nanoparticle fuel additives in normal diesel engines.
Alumina (Al2O3) additives also provide enhancements to fuel combustion and efficiency in engines. Alumina additives blend with biodiesel and other renewable fuels to increase efficiency in engines. When under combustion, alumina nanoparticles form into aluminum (I) oxide and then aluminum metal.2 In both stages, oxygen released goes to fuel combustion, contributing to an increase in complete combustion, therefore, leading to more efficient engines. Specifically, alumina additives work to improve brake thermal efficiency and brake specific energy consumption (BSEC). Researchers found a decrease in BSEC from regular diesel fuels, with a difference of about 10 MJ/kWh at 25% engine load2. This difference diminishes as load increases due to higher fuel demand for optimal performance. For BTE, significant improvements on engine performance were demonstrated. In testing, differences in BTE of approximately 5% between diesel fuels and alumina-infused biodiesels were observed, increasing as load increased.2 TF20- an alumina additive at 20 parts per million- showed the largest increase in BTE for the alumina-based biodiesels, as compared to the diesel fuels2. Since alumina nanoparticles have conductive and radiative properties, their addition to fuels improves heat transfer throughout engines that lead to complete combustion of fuels.2 Also, researchers noted alumina nanoparticles’ high surface area-to-volume ratio as an explanation to improved performance. A high ratio indicates higher reactivity and potential to store energy.2
Throughout the study of nanoparticle-infused fuels, Biodiesel presents itself as one of the leading alternative fuel additives3,4. Biodiesel comes in various forms that exhibit certain characteristics. While naturally produced, biodiesel creates significant problems when in diesel engines; these include an increased viscosity, engine blockages, and an increase in NOx emissions5. To improve its quality, nanoparticles can be added to the fuel. Nano-based additives differ in composition, including metal-based additives, cetane number improvers, and ignition promoters5, and differ in how they improve a fuel (biodiesel in this case). For example, metal-based nanoparticle additives, like cerium and cerium-iron, accelerate the rate of combustion and decrease fuel consumption4. An increased rate of combustion allows for a powerful engine, requiring less fuel for cars to run. As cetane number improves, nanoparticles added to fuels lower the ignition delay- the time lag between injection and start of combustion within an engine5. This lower ignition delay coincided with improved cylinder combustion characteristics that lead to the reduction of the combustion duration.
Biodiesel performance depends on the blend of biodiesel, the feedstock, and the petroleum diesel characteristics6. Another form of biodiesel is the soybean biodiesel that presents an alternative to regular diesel or petroleum-based fuels. Soybean biodiesel blends with nanoparticles, along with regular diesel at varying concentrations, to create an efficient fuel for use in combustion engines (Figure 1).
Figure 1: Steps involved in the fabrication of a nanofuel7
Specifically, tests regarding BTE at various loads showed an increase in BTE when a blend of biodiesel and zinc oxide nanoparticles were used7 (Figure 2). For each test, compression ratios changed to compare BTEs at varying positions in the engine, which included an 18.5:1 biodiesel-to-nanoparticle ratio (Figure 3) and a 21.5:1 biodiesel-to-nanoparticle ratio. BTE increase of up to 20.5% was observed7. Also, researchers saw a decrease in BSFC as the load of nanoparticles increased. Overall, these tests demonstrated that zinc oxide nanoparticles at 50 ppm (SBME25ZnO50) provided an overall enhancement to fuel performance when used in engines.
Figure 2: Scanning Electron Microscopy (SEM) image of Zinc Oxide Nanoparticles7.
Another goal of the use of nano-additives in fuels is to reduce combustion emissions, primarily nitrogen oxide (NOx) and carbon dioxide (CO2) emissions. In the analysis of biodiesels, researchers have found that biodiesel has the potential to be environmentally friendly, burn cleanly and lower levels of carbon monoxide8. For their tests, different blends of biodiesel-diesel and alumina nanoparticles were utilized. Using the blends, researchers measured carbon monoxide emissions through testing for volume of carbon monoxide at brake mean effective pressure (BMEP) for the nanoparticle fuel blends. When compared to 100% diesel, there was a general decrease in percent volume of carbon monoxide emissions as BMEP increased8. Considering the demand for alternative fuel sources, alumina-infused biodiesel blends could present a great option as an alternative fuel source, in terms of reducing significantly some form of emissions. Another promising additive for diesel and biodiesel is graphene-based nanoparticles. Graphene oxide (GO) has shown a lower sooting tendency, whereas graphene nanoplatelets (GNP) has exhibited better emission reduction for NO, CO and hydrocarbons9. Both GO and GNP are attractive fuel additives for improved emission control without any consequences on the filterability and injector wear.
Nanoparticle-infused fuels show promise in combating emissions of carbon monoxide and nitrogen oxides. Through catalysis and catalytic properties of these additives, engines improve their performance and emit lower amounts of carbon monoxide and nitrogen oxides. Titanium dioxide (TiO2) nanofluids showed reduced emission rates when blended with mustard oil biodiesel10. Different particle sizes of TiO2 were infused with biodiesel to perform the tests, with sizes ranging from 100 to 300 parts per million (ppm). TiO2 nanofluids enrich biodiesel fuels with oxygen, leading to more efficient fuel combustion and lower emissions. For carbon monoxide emission rates, tests showed an initial decrease of up to 0.04% at 25% load capacity10 from regular diesel. From tests, TiO2 at 300 ppm saw the largest decrease in emissions by volume10. However, as load increased, so did the emission rates by volume. While still lower than diesel, increased load requires more fuel and results in more carbon monoxide emissions.10
In conclusion, nanoparticles as fuel additives present great potential to reduce emissions and improve fuel efficiency. Nanoparticles, particularly zinc oxide nanoparticles, enhanced engines through improving complete combustion, reducing both carbon monoxide and nitrogen oxide emissions, and decreasing the amount of fuel used in processes. Throughout various studies, brake thermal efficiency and brake specific fuel consumption were shown to improve when working with nanoparticle fuel additives in biodiesel-diesel blends. The future of nanoparticle fuel additives brightens with new improvements to engines and biodiesel, as well as with the creation of nanoparticles with enhanced chemical, thermal and catalytic properties.
Dr. Raj Shah is a Director at Koehler Instrument Company in New York, where he has worked for the last 25 years. He is an elected Fellow by his peers at IChemE, CMI, STLE, AIC, NLGI, INSTMC, The Energy Institute and The Royal Society of Chemistry An ASTM Eagle award recipient, Dr. Shah recently coedited the bestseller, “Fuels and Lubricants handbook”, details of which are available at
A Ph.D in Chemical Engineering from The Penn State University and a Fellow from The Chartered Management Institute, London, Dr. Shah is also a Chartered Scientist with the Science Council, a Chartered Petroleum Engineer with the Energy Institute and a Chartered Engineer with the Engineering council, UK. An adjunct professor at the Dept. of Material Science and Chemical Engineering at State University of New York, Stony Brook, Raj has over 300 publications and has been active in the petroleum field for 3 decades. More information on Raj can be found at
Dr. Steve (Stephanos) Nitodas is currently a member of the Faculty of the Department of Materials Science and Chemical Engineering at Stony Brook University, NY. His expertise lies in the synthesis and applications of nanostructured carbon and polymer nanocomposites. He has served as Coordinator/ Principal Investigator in five (5) EU funded research projects of 4.2 million Euro total budget, and he has been involved as Co-Principal Scientist in thirteen (13) other funded research projects. Dr. Nitodas has worked for several years in the nanotechnology industry, possessing significant know-how related to transfer of knowledge from academia to the industry and the setup of startup companies.
Nicholas Douglas and Nathan Aragon are part of a thriving internship program at Koehler Instrument company and students of chemical engineering at State University of New York, Stony Brook, where Dr. Shah currently heads the External advisory board of directors.
1Norhafana, M., et al. “A Review of the Performance and Emissions of Nano Additives in Diesel Fueled Compression Ignition-Engines.” IOP Conference Series: Materials Science and Engineering, vol. 469, 2018, p. 012035., doi:10.1088/1757-899x/469/1/012035.
2 Venu, Harish, et al. “Combined Effect of Influence of Nano Additives, Combustion Chamber Geometry and Injection Timing in a DI Diesel Engine Fuelled with Ternary (Diesel-Biodiesel-Ethanol) Blends.” Energy, vol. 174, 1 May 2019, pp. 386–406., doi:10.1016/j.energy.2019.02.163.
3 Khan, Saddam, et al. “Nanoparticles as Fuel Additive for Improving Performance and Reducing Exhaust Emissions of Internal Combustion Engines.” International Journal of Environmental Analytical Chemistry, 5 Feb. 2020, pp. 1–23., doi:10.1080/03067319.2020.1722810.
4 Dwivedi, Gaurav, et al. “Impact Analysis of Biodiesel on Engine Performance – A Review.” Renewable and Sustainable Energy Reviews, vol. 15, no. 9, 14 Sept. 2011, pp. 4633–4641., doi:10.1016/j.rser.2011.07.089.
5 Db Ganesh, “A Review On Nanoparticles As Fuel Additives In Biodiesel”, 22 Dec 2018
6 U.S. Dept. of Energy. “Biodiesel Fuel Basics.” Alternative Fuels Data Center: Biodiesel Fuel Basics, U.S. Department of Energy, afdc.energy.gov/fuels/biodiesel_basics.html.
7 Gavhane, Rakhamaji S., et al. “Effect of Zinc Oxide Nano-Additives and Soybean Biodiesel at Varying Loads and Compression Ratios on VCR Diesel Engine Characteristics.” Symmetry, vol. 12, no. 6, 22 June 2020, p. 1042., doi:10.3390/sym12061042.
8 Prabu, A. “Nanoparticles as Additive in Biodiesel on the Working Characteristics of a DI Diesel Engine.” Ain Shams Engineering Journal, vol. 9, no. 4, 8 July 2017, pp. 2343–2349., doi:10.1016/j.asej.2017.04.004.
9 Nivin, Chacko and Thangaraja, Jeyaseelan “Comparative evaluation of graphene oxide and graphene nanoplatelets as fuel additives on the combustion and emission characteristics of a diesel engine fuelled with diesel and biodiesel blend”, Fuel Processing Technology, vol. 204, July 2020, p. 106406.
10 Pandian, Amith Kishore, et al. “Influence of an Oxygenated Additive on Emission of an Engine Fueled with Neat Biodiesel.” Petroleum Science, vol. 14, no. 4, 2017, pp. 791–797., doi:10.1007/s12182-017-0186-x.