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Alternative fuels from fat residues and waste materials can give old diesel generators a new lease on life. Synthetic diesel obtained from hydrotreated vegetable oil is used in backup generators to recharge batteries. C.A.R.E.-Diesel, the brand-name product made by the Finnish mineral oil company Neste, is a paraffinic diesel fuel which is produced by the hydrogenation of old cooking oil, fat residues, and waste materials. The acronym C.A.R.E. stands for CO2 reduction, Arctic grade, Renewable, and Emission reduction.


While hydrotreated vegetable oils (HVO) are permitted as alternative fuel for use in traffic vehicles in Scandinavian countries, Spain, the Netherlands, and Austria, HVO can only be used as an additive to conventional diesel fuel in Germany. Synthetic diesel may be sold as clean fuel (HVO 100) only for use in busses, trucks, and off-road vehicles, as well as generators. The use of HVO in combustion engines is nearly carbon-neutral thanks to its emission of significantly less nitrogen oxide, particulates, carbon dioxide, and hydrocarbons.


Oliver Graff, whose Cologne-based rental house CamCar is charging camera and lighting batteries with solar power from the company‘s roof top, considers HVO as an appropriate bridge technology thanks to its high greenhouse gas reduction characteristics. His equipment rental house already has the necessary infrastructure to retank trucks and generators with this
regenerative fuel. “On our company premises in Cologne, we have two old oil tanks that we intend to clean and use as the company’s HVO fuel station”, says the Camcar CEO.


This solution has several advantages. Since HVO doesn’t contain oxygen, the fuel has a longer shelf life than fossil-sourced diesel, and it is heat- and cold-resistant. The most important factor is that HVO can be used for diesel motors in trucks and generators without retrofitting or conversion. “We thereby avoid hardware obsolescence in our fleet, and we substantially reduce costs”, emphasizes Oliver Graff, who wants to retrofit his vehicles with fuel cells when green hydrogen becomes available on a larger scale.


A clean alternative to conventional diesel generators is mobile solar-powered generators that operate noiselessly and entirely without emissions. The Dutch startup company Volta Energy developed a 45 kVA generator that comes as a hybrid system with a backup generator. The main generator consists of solar panels, batteries, and power inverters. Peak loads and power failures are compensated by an HVO 100-powered backup generator. Any leftover capacity is used to charge the batteries.


The 45 kVA solar generator is equipped with a three-phase power inverter with a peak power maximal 12 kW per phase, which can balance either the peak loads or load drops of certain solar modules due to varying sunlight. The amorphous solar modules have a peak performance of 5.28 kW, but they generate less on cloudy days. The continuous output is an average 3 kW. The solar generator is mounted on a trailer, and it meets the stage 5/euro 6 emission standard.


Photo: © Volta Energy, video: © Green Film Shooting

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