Benefits of biodiesel over petrodiesel are: A. Biodiesel contains virtually no…
2024
Benefits of biodiesel over petrodiesel are:
A. Biodiesel contains virtually no sulfur.
B. Biodiesel emits substantially lower carbon monoxide (CO).
C. Biodiesel is a better lubricant than petrodiesel.
D. Biodiesel emits significantly lower Oxides of Nitrogen (NOx) than petrodiesel.
E. Particulate emission by biodiesel is much lower than that of petrodiesel.
Choose the correct answer from the options given below:
Answer: C. A, B, C, E only — Concept — Biodiesel is a fatty-acid methyl ester (FAME) made by transesterifying vegetable oils or animal fats, and two properties of the resulting fuel shape…
- A.
A, B, C, D only
- B.
B, C, D, E only
- C.
A, B, C, E only
- D.
A, B, D, E only
Show answer & explanation
Correct answer: C
Concept — Biodiesel is a fatty-acid methyl ester (FAME) made by transesterifying vegetable oils or animal fats, and two properties of the resulting fuel shape most of its emission behaviour. First, the feedstock is biological, so the fuel carries essentially no sulfur. Second, the ester group leaves roughly 11 per cent oxygen chemically bound inside the molecule, and that bound oxygen makes combustion more complete, which suppresses the products of incomplete combustion — carbon monoxide, unburned hydrocarbons and particulate matter. Oxides of nitrogen behave differently. Averaged over engines and test cycles, biodiesel shows a modest NOx increase, usually attributed to a somewhat higher flame temperature together with the slightly advanced injection timing that biodiesel’s higher bulk modulus produces in mechanically injected engines. The magnitude of that shift depends on feedstock, blend level, engine design and calibration, operating conditions and after-treatment, so read it as a typical tendency rather than a universal law. Separately, the polar ester group gives biodiesel far higher lubricity than the hydrotreated, sulfur-stripped petrodiesel it replaces.
Application — Check each of the five claims against those mechanisms.
Claim | Direction versus petrodiesel | Governing mechanism |
|---|---|---|
A. Sulfur content | Virtually eliminated | Plant oils and animal fats contain almost no sulfur, so sulfur dioxide and sulfate particulate essentially disappear |
B. Carbon monoxide | Substantially lower (about 48 per cent lower for pure biodiesel in the US EPA analysis) | Fuel-bound oxygen completes the oxidation of carbon monoxide to carbon dioxide |
C. Lubricity | Markedly better | The polar ester group restores the lubricity lost when sulfur is hydrotreated out of ultra-low-sulfur diesel; a 1–2 per cent blend already suffices |
D. Oxides of nitrogen | Typically slightly higher (about 10 per cent higher for pure biodiesel in the averaged US EPA data), not lower | A higher flame temperature together with advanced injection timing raises thermal nitrogen oxides — the documented biodiesel NOx penalty; its exact size varies with engine, blend and operating conditions |
E. Particulate matter | Much lower (about 47 per cent lower for pure biodiesel) | Oxygen-assisted complete combustion plus the absence of sulfate precursors |
Cross-check — Four of the five claims describe genuine benefits; the claim about oxides of nitrogen runs the other way, because nitrogen oxides form the one regulated pollutant class that biodiesel does not reliably reduce. The set of true benefit statements is therefore exactly A, B, C and E. Read against that set, only the combination “A, B, C, E only” keeps all four supported claims while excluding the nitrogen-oxide claim; every other offered combination carries the nitrogen-oxide claim in and drops one supported claim.
Result — A, B, C, E only.