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Wednesday, 13th December 2017

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Viv Forbes

Viv has a degree in Applied Science Geology and is a Fellow of the Australasian Institute of Mining and Metallurgy

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Is Diesel the New Green Fuel?


Are Climatists giving a green tick to diesel power?

Ten thousand professional climate crusaders recently attended yet another Climate Carnival in Lima, Peru. Did they use green power to minimise their carbon footprint? No way; massive diesel generators were trucked in on diesel-powered lorries because the local hydro/solar power could not cope. The delegates were also moved between hotels and the venue in more than 300 diesel buses – few bothered to walk or ride bicycles.

In sunny Spain, the government solar subsidies were so generous that some entrepreneurs managed to produce solar energy for 24 hours per day. However, inspectors discovered that diesel generators were being operated at night, thus producing great profits in selling “solar” energy to the grid.

Then in “go-green, vote-blue” Britain, wind power is proving so erratic that thousands of reliable diesel generators are being installed by utilities and businesses to maintain power when the grid becomes unstable.

Finally we have people who disconnect from the grid, aiming to become independent by generating their own power from small solar and wind installations. After the first long spell of cloudy windless weather, most turn to a reliable on-demand diesel backup generator to keep the fridge running and the lights on.

It seems that diesel is the new “green” fuel. In some bitter winter, when real blackouts hit UK or Europe, maybe clean “green” coal will be re-discovered and cranked up again.



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Comments

I dream of removing my place from the grid.

I'm off, past my 100% efficiency time. Hafta go to the land of nod and produce some 100% efficient Methane gas so as to give the Missus a twitch of the nose and the grumbles from the mouth.

You know what DT I've had enough of text books in my lifetime; your copy and paste is what? Is it trying to tell me in basic terms the difference between a diesel and petrol motor? FFS I probably learned all that whilst you were still in nappies. So the ergonomic efficiency between diesel and petrol is of what use to me?

That is true Obelix, but no filtration or cleaning system is 100% efficient. There has been a lot of progress made, but pollution free engines are not really technically feasible.

Sigh. DT diesel motors use a diesel particulate filter in their exhausts to eleminate your bad carbon particles, works on a similar way that a cat converter works in a petrol motor.

Obelix the info is out there. You just have to look.

Gasoline (petrol) engines
Modern gasoline engines have a maximum thermal efficiency of about 25% to 30% when used to power a car. In other words, even when the engine is operating at its point of maximum thermal efficiency, of the total heat energy released by the gasoline consumed, about 70-75% is rejected as heat without being turned into useful work, i.e. turning the crankshaft.[1] Approximately half of this rejected heat is carried away by the exhaust gases, and half passes through the cylinder walls or cylinder head into the engine cooling system, and is passed to the atmosphere via the cooling system radiator.[2] Some of the work generated is also lost as friction, noise, air turbulence, and work used to turn engine equipment and appliances such as water and oil pumps and the electrical generator, leaving only about 25-30% of the energy released by the fuel consumed available to move the vehicle.

At idle, the thermal efficiency is zero, since no usable work is being drawn from the engine. At low speeds, gasoline engines suffer efficiency losses at small throttle openings from the high turbulence and frictional (head) loss when the incoming air must fight its way around the nearly closed throttle; diesel engines do not suffer this loss because the incoming air is not throttled. At high speeds, efficiency in both types of engine is reduced by pumping and mechanical frictional losses, and the shorter period within which combustion has to take place. Engine efficiency peaks in most applications at around 75% of rated engine power, which is also the range of greatest engine torque (e.g. in most modern passenger automobile engines with a redline of about 6,000 RPM, maximum torque is obtained at about 4,500 RPM, and maximum engine power is obtained at about 6,000 RPM). At all other combinations of engine speed and torque, the thermal efficiency is less than this maximum.

A gasoline engine burns a mix of gasoline and air, consisting of a range of about twelve to eighteen parts (by weight) of air to one part of fuel (by weight). A mixture with a 14.7:1 air/fuel ratio is said to be stoichiometric, that is when burned, 100% of the fuel and the oxygen are consumed. Mixtures with slightly less fuel, called lean burn are more efficient. The combustion is a reaction which uses the air's oxygen content to combine with the fuel, which is a mixture of several hydrocarbons, resulting in water vapor, carbon dioxide, and sometimes carbon monoxide and partially burned hydrocarbons. In addition, at high temperatures the oxygen tends to combine with nitrogen, forming oxides of nitrogen (usually referred to as NOx, since the number of oxygen atoms in the compound can vary, thus the "X" subscript). This mixture, along with the unused nitrogen and other trace atmospheric elements, is what we see in the exhaust.

In the past 3–4 years, GDI (Gasoline Direct Injection) increased the efficiency of the engines equipped with this fueling system up to 35%. Currently, the technology is available in a wide variety of vehicles ranging from less expensive cars produced by Mazda, Ford and Chevrolet to more expensive cars produced by BMW, Mercedes-Benz, and Volkswagen Auto Group.

Diesel engines
Engines using the Diesel cycle are usually more efficient, although the Diesel cycle itself is less efficient at equal compression ratios. Since diesel engines use much higher compression ratios (the heat of compression is used to ignite the slow-burning diesel fuel), that higher ratio more to air pumping losses within the engine. Modern turbo-diesel engines are using electronically controlled, common-rail fuel injection, that increases the efficiency up to 50% with the help of geometrically variable turbo-charging system; this also increases the engines' torque at low engine speeds (1200-1800RPM).

Ummmm Trumby; sulphur comes out of the ground in NZ due to Volcanic activity, what has that got to do diesel? If you're referring to sulphur as a lubricant, sorry you're wrong; it's the additives they use to remove the sulphur from diesel that causes the diesel to lose it's lubricity(?). BTW You're not Reco from Bolt are you?

Petrol engines do not show as much carbon particles in their exhaust, as the lighter petrol fractions are more completely burn. But they have plenty of other noxious gases in them as well. There is more info readily available http://www.crypton.co.za/Tto know/Emissions/exhaust emissions.html

Obelix a component of diesel exhaust gas is particulate carbon. I.e. small carbon particles that are not burnt during combustion. These small particles create the smog or haze of diesel exhaust (especially under full load). The carbon particles can possibly induce asthma if an individual is predisposed to it. There is a lot of info on google on diesel exhaust smoke induced asthma.

More thermally efficient? Watta fuck ya talking about? Diesels use more higher compressions because they need the higher compressions to achieve the heat to ignite the fuel whereas petrol uses a spark, dunno about being more thermally efficient. If anything diesels create more heat.

Sulfur an upper cylinder lubricant was removed from diesel because of supposed environmental concerns but strangely enough the stuff comes out of the ground naturally in places like NZ .

How are exhaust fumes from a diesel inherently dirtier DT? Don't understand.

Diesel engines are vastly more efficient in the low end torque range, hence their predominance superior performance in larger equipment as in trucks and plant equipment. They also show their superiority in smaller engines as well (as in pumps and generators).

Diesel exhaust fumes are inherently dirtier than other internal combustion engines due to carbon particles that show up as black smoke. Late model diesel have been greatly improved on this area. Overall the Diesel engine is substantially more thermally efficient due to higher compression ratios than similar petrol engines. I've known several customers running Diesel engines on old fish and chip oil. It has some problems but works fine.

Didn't realise spelling was part of the equation diarrhea lame brain. And what problems with diesel fuel are you referring to diarrhea head?

Viv is pointing out the extreme hypocrisy of Climate Conferences speaking out about using fossil fuels, then using fossil fuels like there was no tomorrow during the conference. There would have been enormous savings of pollution by not having the conference at all. Typical waste of resources for no net gain.

The only problem with diesel fuel grown from crops, is that if everyone started to use it, there would not be enough arable land to grow enough crops for fuel alongside existing food crops. Also, it still works out more expensive than diesel fuel distilled the conventional way.

Hey sandud, I'm an engineer and have done a lot of work with Diesel engines for the last 40 years. Viv is correct in what he has written. What's the problem?

the point of the article is clear, diesel is being used to prop up the renewable argument, transparent as could be, hence diesel is the new green fuel.