v8dave wrote:Thank you for taking the time to summarise the vast array of amateur research on the use of vegetable oil.
As far as I'm concerned the use of any fuel in an engine produces 'carbon' emissions, the only difference between the fuels is the timescale over with the carbon has been accumulated.
Many organisations involved in campaigning to protect the environment are against the replacement of conventional diesel with biodiesel because of the intensive agricultural effort required for production.
UK duty payable is governed primarily be HMRC regulations, it will take some time for me to read them and the regulations they reference.
Couple more points, is a good discussion about renewable fuels.
Remember that Herr Rudulph designed the first diesels to run on either petroleum diesel or vegetable oil: it’s not a new idea.
And again, looking at the big picture, we don’t have an unlimited supply of oil: we’re forced to produce from more severe environments to meet demand. So that’s more offshore, deeper offshore, and further North (and South). Or else fracking, and tarsands. All have environmental issues, and the risks of spills etc increases.
In terms of reducing carbon footprint you are without question better to burn bio-derived fuel than fossil fuels. Even conversion from coal to oil releases the carbon. It’s not correct to say the only difference in carbon emissions is the time scale. For plant based systems, the plants grow, take in carbon dioxide, release oxygen, then die off, releasing the carbon then. Which is taken in by other plants.
For fossil fuels, we aren’t making any more fossil fuels/coal anymore: it’s all been done. So anything you dig up/pumpout and burn adds directly to the carbon emissions. It doesn’t come back. Only if you make a conscious sequestration effort can you get it back. And these processes are fairly energy hungry, what do you use to drive them? Nuclear power?? Not solar/wind power, that’s all ear marked to replace the dirty coal thay’s being burned..... I’m ok with using nukes to do it, but most greens are scared of them.
As far as “amateur research”, well i can give you academic papers if you want.
In general, carbon emissions tend to decrease, even tking into account most veggie fuels have slightly lower energy content, and sulphur emissions drop. NOx is a more complex story: it depends on the type/blend of fuel, engine design, and how operated.
But the point is that if bio diesel is used on a larger scale, you would need to modify the diesels somewhat to use it optimally. And also control the type of veggie fuel you use. That’s if you want to do it on a very large scale.
Xue et al 2011 was the most recent review i found, but i’m sure there’s others.
https://www.sciencedirect.com/science/a ... 2110003850
Nwafor 2004 found that veggie fuel produced slightly more carbon monoxide but less hydrocarbon contaminants. And the i crease in carbon was because of adjusting the operating temperature to allow for the higher viscosity of veggie oil. If you ran a hybride system you wouldn’t need to do that.
https://www.sciencedirect.com/science/a ... 3404000625
Graboski and McCormack found mostly beneficial changes, but agree with the gist of my summary.
https://www.sciencedirect.com/science/a ... 8597000348
https://www.sciencedirect.com/science/a ... 8109003826
https://www.sciencedirect.com/science/a ... 6110002590
Dorado et al 2003 found reductions in carbon and suplhur compounds, and a mix of increase/decrease for NOx compounds depending on the case and which compounds.
https://www.sciencedirect.com/science/a ... 6103000346
There are a few more of interest:
https://www.sciencedirect.com/science/a ... 8597000348
https://www.sciencedirect.com/science/a ... 0400000807
Anyways, i don’t think it makes sense to grow bio-fuel crops everywhere: you’d want to optimize the crop with the growing conditions. But it could make a nice cash crop for a country that doesn’t have a lot of other resources, except land and sunshine.