Thursday 18 April 2019

Time to go HVO, says DAF

UK truck market leader DAF has called for the industry to throw its weight behind a conversion from conventional fossil-derived mineral diesel to synthetic HVO (hydrogenated vegetable oil).

Speaking at a ceremony to mark 90 years since the van Dorne brothers set up their first blacksmithing workshop in Eindhoven – forming the foundation of van Dorne’s Aanhangwagen Fabriek (van Dorne’s trailer factory) company, or DAF, which was incorporated in 1932 – DAF’s chief engineer and director of product development Ron Borsboom mounted a robust defence of the modern diesel engine.

Euro 6 diesels had reduced NOx emissions by 95 per cent from Euro 1 levels, with particulates falling by 97 per cent, he pointed out.

There was political pressure to introduce new fuels, but it was important to ensure that any new fuels generated a CO2 saving that was ‘well-to-wheel’ and not just ‘tank-to wheel’: in other words, their production and consumption should yield a total CO2 saving over other fuels.

“In the past, DAF has not been keen on biofuels,” he said, pointing out the questionable morality of taking agricultural land out of food production to produce fuel.

“But this has changed with the introduction of HVO. Here we have a biofuel which is a by-product of food production. DAF’s current diesel engines can run on HVO without modification or adjustment to their maintenance schedule, and switching to HVO generates an immediate 80 per cent saving in CO2 emissions compared to fossil diesel.”

DAF’s UK marketing manager Phil Moon told Transport Operator: “Using HVO requires no engine modifications and it can be mixed with conventional diesel in any concentrations.

“Furthermore, using HVO, which is a synthetic diesel, can cause a significant reduction in harmful emissions as well as greenhouse gases and potentially improve the emissions performance of earlier diesels to closer to Euro 6 levels.

“There are two interlinked issues currently holding back the introduction of HVO in the UK: knowledge and taxation. There’s currently no fuel-duty discount or other incentive to use HVO as a road fuel; and although it is available, few operators seem aware of the benefits of it, not least in giving a lead in low-carbon strategies.”

Unlike conventional biodiesel, which is produced by the transesterification of vegetable oil to produce FAME (fatty acid methyl esters), HVO is produced by adding hydrogen to vegetable oil to produce a liquid with the chemical structure Cn Hn + 2.

HVO is a paraffinic hydrocarbon that is free of oxygen, unlike FAME, which has a limited shelf-life and is highly prone to contamination by comparison. Unlike conventional mineral diesel, it is naturally free from sulphur and aromatic content, it also has a higher cetane number and calorific value.

Tests on a Cummins four-cylinder ISB Euro 5 diesel conducted by independent researchers with the assistance of the engine manufacturer indicated that running 100 per cent HVO caused a slight reduction in peak engine power (down from 135.6 kW to 135 kW) compared to mineral diesel because of the lower density of the biofuel.

However, fuel consumption was reduced by 2.3 per cent, thanks to the higher mass-based energy content of the fuel.

With lower cloud and filter-plugging points than FAME and conventional diesels, HVO would also need little or nothing by the way of the cold-weather additives which currently increase diesel fuel consumption in the winter. However, it lacks the lubricity of mineral diesel, meaning that it may not be suitable for some applications, including engine designs that are reliant on diesel to lubricate the fuel pump.

HVO has been approved as a fuel for recent and/or current engines by manufacturers including Cummins, DAF, MAN, Mercedes-Benz, Scania and Volvo.

A wide range of material can be used to produce HVO, including vegetable matter and slaughterhouse waste. By-products of HVO production are naphtha (a liquid hydrocarbon which can be used for heating), and CO2 and CO, which can be used to produce methane, another fuel.

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