How does biodiesel impact engines?

let's talk about the impact of biodiesel so first of all what exactly is biodiesel so you'll remember that most diesel obviously is derived from crude oil sources so we go out we explore we drill we pump this stuff out of the ground then we take it to a refinery we refine it into different products some of those become lubricants some of them become diesel right well obviously biodiesel doesn't really work the same the same way we start off with some kind of bio product some kind of living organism typically a plant right so palm plantations are where a lot of biodiesel is derived from sunflower seeds is another really good example we basically harvest these crops and then we use the seeds right and we use the oil from the seeds so just like you press and you get olive oil you can press a lot of these other seeds and nuts in order to get an oil right and with a little bit of refining we can then basically turn them into biodiesel now sometimes you'll hear it called fame or f-a-m-e which stands for a fatty acid methyl ester right that's effectively what biodiesel is so what exactly is that all right so let's take the different components of the name and sort of break it down let's say i have a straight carbon chain now of course each of these carbons has a couple of adjoining hydrogens on it i don't show those for simplicity's sake so let's just say that we have a straight hydrocarbon chain well if i have an acid functional group on the end then right that is what we typically call a fatty acid when it comes to organisms right so we have lots of fats in us whether they're fatty acids or triglycerides so do plants right they they generate these these fatty acids in in their seeds or nuts all right so we have an acid functional group now what's great about some of these plant varieties is that they happen to generate fatty acids which are just the right size for diesel so if you'll remember right diesel comes out of the ground and it's just crude oil and the exercise of refining is to kind of separate these out into different fractions so if we have gases you know methane only has one carbon but you know methane propane butane you start to increase the number of carbons and as you increase the number of carbons then the end product gets thicker or more viscous so then if it's about eight carbons long that's typically you know gasoline or petrol 12 carbons long is approximately kerosene and 16 carbons long is approximately diesel well as it happens with a lot of these bio-derived products what we get is you know something that looks like this this in particular is one of a handful of vegetable fatty acids and the one that i've got on screen happens to have 18 carbons which corresponds to something called stearic acid now all of these different ones that i've got up on screen have different carbon chain lengths you know 14 16 and 18 is very very typical so you know palmitic acid which has 16 carbons the clue is in the name right palmitic is because it's very common in palm oil now what is the difference between steric oleic and linoleic acid because they all have 18 carbons in their chain well it's got to do with what we call saturation so what i'm showing on screen here with a completely straight carbon chain is what we call a saturated fatty acid so in your diet you would hear it called a saturated fat that effectively means that there are no double bonds anywhere along the carbon chain when we get to oleic acid what it means is that there is a double bond somewhere in the chain it doesn't really matter where in the chain it is but somewhere along the chain we have a single double bond that actually affects the shape of the molecule too because double bonds tend to sort of bend the molecule so now because we have a single double carbon bond in the in the link we would call this a monounsaturated fatty acid so it's unsaturated because it has a double bond and it's monounsaturated because there is a single double bond if we were to have a second double bond in the chain then we would call it a polyunsaturated fatty acid and this in in this instance we would call it linoleic acid so it's 18 carbons long but it has two double bonds in it and the position of those double bonds can vary now what's important about saturation you know why why are double bonds undesirable well if you remember back to our api base oil groups for lubricants one of the things that defines group 1 2 and 3 mineral oils is the degree of saturation and the more saturated the the end product is the the higher quality the product is now why is that it's because in a double bond the second bond is easier to break than a single bond so it's less oxidatively stable so molecules that are unsaturated tend to be less oxidatively stable now that's a little bit of a problem when it comes to biodiesels and the reason for that is because if you look at the composition of some very very common vegetable oils what you'll see is that for the most part they are unsaturated molecules so what i'm showing here is if you remember blue and green are palmitic and stearic acids so 16 and 18 carbon long fatty acids but those are the unsaturated sorry the saturated ones the unsaturated are represented by the bright red and the bright purple which are the oleic and linoleic acids so what you can see is especially the sunflower oils but even the palm oils are more than half unsaturated and so that makes them oxidatively unstable so if we go back to this idea we're not we're not quite complete yet we've explained fatty acid and we've explained saturated and unsaturated so what's the methyl ester part well basically in order to create biodiesel we take these fatty acids and we react them with methanol right so methanol is the methyl part of the name and it undergoes a reaction which we call an esterification process so basically we are creating an ester right so if we have an acid and an alcohol so we had uh linoleic acid plus methanol acid plus alcohol makes an ester plus water and so that's the esterification reaction and so that's how we get to fatty acid methyl ester so that's effectively what the biodiesel molecules are now when they're marketed you'll typically see them uh called something like you know b5 biodiesel or maybe it's b10 or b20 so what does that number refer to so b20 means that the diesel that you're putting in your engine is 20 biodiesel and therefore you know by extension it's 80 crude oil derived right so it's 20 natural 80 crude oil mineral oil if you want to call it that now around the world there are different rules and regulations about the biodiesel content right so let's say for example in kind of my backyard in in my part of the world indonesia brought a mandate in 2020 that all the diesel across the country be b30 right which is 30 percent biodiesel or plant derived malaysia has a view this year to bringing about b20 so 20 biodiesel mix um now there are a couple of drivers behind that one these countries tend to import a lot of diesel and so they want to rely less right and as it happens they are they have huge palm plantations right so they have a a rich plant source to be able to derive biodiesel from if you go to somewhere like australia it varies by jurisdiction so in my state of new south wales i think the rule is that two percent of the volume which is sold by fuel distributors needs to be bio-diesel right and it varies state by state the same goes for the u.s i think the mandates vary by state and that's true of places all across the world but the fundamental kind of underpinning trend is that the volume of biodiesel continues to increase year on year and it's starting to grow its market share as people look for kind of renewable fuel sources now we could spend a whole nother you know hour talking about the the environmental costs versus benefits of biodiesel obviously you know if you're growing monoculture plantations that can be bad for the environment we're not going to get into it here but what i do want to focus on is how it affects the engine and the lubricant system so when you have an engine the one thing that we cannot avoid as much as we would love to is some degree of blow-by that occurs past the rings and so some measure of kind of blow-by and fuel dilution of the lubricant is going to be unavoidable so what is kind of different about biodiesel well first of all because it's so unsaturated it's less oxidatively stable so we tend to get as it mixes in with the lubricant it breaks down you know typically oxidation will lead to things like viscosity increases and more deposits it's also less hydrolytically stable being an ester when it comes into contact with water right it breaks down back into an acid right so we are creating acids all the time and then we can run into problems with corrosion and particularly in the crankcase we'd be concerned about the crankcase bearings so that hydrolytic stability can really be a problem in engines because remember water is also a byproduct of combustion right it's it's unavoidable that water will get into the crankcase so the combination of water plus a bioderived esta means that you're going to be producing acids there is also some evidence that there is a negative interaction that happens with certain types of viscosity modifiers and you can run into some low temperature pump ability issues this seems to differ depending on the type of viscosity modifier but you know without much information about the formulations of some of the diesel engine oils it's very difficult to predict when this will happen there is also some evidence that it can affect the seal swell of different types of materials the evidence seems to be that for the most part it's okay but in nitro rubber and nylon seals it can have an effect on hardness and the degree to which these materials swell and ultimately when you put all this together you end up with shorter oil drain intervals so that's the the major impact on the lubricant on top of that we're also increasing fuel consumption because the energy density of biodiesel is less than crude oil derived diesel right so although we're theoretically going from renewable sources we're actually increasing the amount that we have to burn in order to power our engine one of the other interesting impacts is that it biodiesel doesn't volatilize the way that petroleum diesel does so of course with with diesel typically it's uh you know direct injection so we're we're spraying uh effectively a um fuel mist into the combustion chamber and the whole point of the injector is it is it's trying to atomize the fuel well if you compare what biodiesel looks like versus petroleum diesel it tends to clump up a little bit more it's not as evenly distributed so what does that mean for our lubricant well when we get less atomization of the fuel that means that in local areas we would say that it is fuel rich right and so we're entering a rich burn environment when that happens we typically have more incomplete combustion and the product of incomplete combustion is soot so generally when we're burning a biodiesel we end up with more soot in the crank case right and soot obviously leads to increases in oil viscosity because of the loading of solids and it can also start to wear the engine components as well because when soot agglomerates it becomes abrasive so that's another negative consequence of the use of biodiesels in engines again you know just to kind of belabor the point a little bit but the hydrolysis reaction is basically the reversal of the esterification reaction so when these esters come into contact with water we are creating carboxylic acids as well as alcohols now there is obviously some regulation that has sprung out about this so the us and europe have standards around biodiesel in the us you'll see it as astm d6751 and in europe it's uh en 14214 right that really kind of just sets the standard for what biodiesel has to be but you really need to look at the engine manufacturers to see did they design the engines with biodiesel in mind or if they didn't design it specifically with biodiesel in mind how have they have they since tested the use of biodiesel in their engines to ensure that it's not going to cause a lot of damage now this isn't by any means an exhaustive list this is just what i could find the the the let's say the information may have been updated since you see this since this video was published so always make sure that you are going back to the manufacturer documentation to ensure that you have the most up-to-date information but here what you can see is that effectively for most of the manufacturers they are defining that uh concentrations up to five percent of of biodiesel are generally okay some of them go up to 20 is okay um and then some say well you really need to maybe check so as an example if you look at the scania list it says you know b5 is okay if you want to go above that you can but you have to shorten your oil drain intervals and then most of them will also say that the actual biodiesel that you're using must meet either the astm or the en spec right so that's that's a really important thing now one thing that we should take away from this is remember that indonesia had had mandated b30 diesel be used and that kind of goes against what most of the engine manufacturers have really approved for use in their engines so that's going to be a really interesting clash to see what happens in the indonesian market over the long term what does the performance of their engines do when running on this b30 so that's been a very quick primer on biodiesel as well as some of the downsides to using it obviously i'm not saying that you should never use biodiesel but just be cautious about some of the negative consequences and be on the lookout for it especially in your oil analysis results

Channel: Lubrication Explained

Views: 30,107

Keywords: Lubricants, Lubrication, Reliability, Machinery, Engineering, Assets, Maintenance

Id: ZcnfNN5M2as

Length: 15min 35sec (935 seconds)

Published: Fri May 13 2022