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Dutch ORC with Finnish research roots looking to branch out

Founded in 2001 Triogen’s Organic Rankine Cycle (ORC) technology was a result of research cooperation with the Lappeenranta University of Technology in Finland. Fifteen years on the Netherlands-headed company is seeking to branch out into other waste heat to power applications.

Founded in 2001 the basis for Triogen’s Organic Rankine Cycle (ORC) technology was a result of research cooperation with the Lappeenranta University of Technology in Finland. Fifteen years on the Netherlands-headed company is seeking to branch out into other waste heat to power applications.The first experimental ORC model was set-up for duration tests at a landfill site in Groningen, the Netherlands in 2006 with the first commercial pilot models coming out in 2008.

– The end of 2010 saw the commercialisation and international launch of the first projects abroad and today we have installations on 40 sites in 11 countries in Europe. These include biogas plants, sawmills, landfills, mines and sewage treatment plants, said Henning von Barsewisch, CEO for Triogen.

Proprietary high-speed generator

ORC is a thermodynamic process whereby heat is transferred to a fluid at a constant pressure. The fluid is vaporised and then expanded in a vapour turbine that drives a generator, producing electricity. The working principle of a high-temperature ORC is similar to that of a steam cycle but uses an organic fluid instead of water. According to von Barsewisch, this allows for better performance and efficiencies at lower temperature (> 350 °C) heat sources typically found in engine exhaust gases. A feature of the Triogen ORC is that the working fluid, toluene, is heated directly by the heat source without an intermediate loop.

– This together with few moving parts and readily available components means high availability and low maintenance, which increases efficiency and reduces the footprint as well as installation and operational costs, said von Barsewich. A core technology developed and employed by Triogen in its ORC is a proprietary high-speed turbo generator (HTG). This unit consists of a housing, a turbine, an electrical generator and a pump. The unique feature is that the latter three components are placed on one shaft eliminating the use of gears.

– This means that the turbine drives both the generator and the pump. The rotational speed of the generator and pump is equal to the rotational speed of the turbine, von Barsewich explained. The bearings are lubricated with toluene, which is also the working fluid so no separate lubrication system is used.

– The housing is a hermetically sealed unit and constructed in such a way when wear occurs or even in the unlikely event of a damage, the working fluid will stay remain inside the housing at all times, preempting a question on risks associated with high-speed rpm failures.

New refurbished market

According to von Barsewisch the company’s ORC fleet is nearing 600 000 operating hours with still plenty of run-time left on the earliest installations. However some are already nearing the end of their economic life opening up a new albeit limited “second-life” market.

–  This can happen because the feed-in-tariff runs out or that the heat source is for some reason no longer available. It does though allow for a new refurbishment business case that is beneficial to all parties, he said. He explained that the company is discussing buy-back with Triogen ORC owners planning to decommission the unit. The idea is then to update and refurbish them and offer to the market at “a significant discount” compared to a new one.

– Thus for owners planning to decommission a unit, the ORC may still represent a value. The refurbished ORC undergoes the same factory acceptance test that a new ORC is subjected to and comes with the same warranty. Whilst better pricing is generally of interest, second life ORCs are really an option that can make projects with lower energy prices, limited heat sources or limited annual run-time more economical, von Barsewich said.

(Bio)diesel gen-sets

Although the vast majority of Triogen installations have been on gas engine or biomass burner applications, there is another (waste) heat source that may prove the entrance ticket to remote applications – heat from diesel gensets.

– There are many remote regions in the world that use diesel-fueled gen-sets to secure electricity production and where the fuel is relatively expensive. You can find such units on islands of Spain, Portugal and Greece as well as in off-grid locations in Africa and Asia, said von Barsewisch.

– The savings are very substantial for such site operators, the payback period can be a short as 2 years when diesel prices are high. To produce the same amount of power, base load engines can reduce their fuel consumption by over 300 000 litres of diesel per year because the ORC turns the exhaust heat into power that the engine doesn’t need to produce. The ORC can easily be retrofitted, there is no modification or change to the engine necessary, it only runs at slightly reduced power.

– We even have some funding opportunities to accelerate the start in this market, such as a grant from the Dutch government for some projects. We are looking for sales partners and operators to take our proven technology to a new application, ended Henning von Barsewisch.

5302/AS

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