Queen’s research driving towards key renewable energy milestones

24 Jan 2017

Queen’s University Belfast. Image: Brendan van Son/Shutterstock

Emily McDaid outlines two research projects underway at Queen’s University Belfast in renewable energy – one in dual-fuel transport and the other in waste heat recovery.

To have a clean, secure future for all of society, we need to eliminate our dependence on diesel. A Centre of Advanced Sustainable Energy (CASE) research project is underway at Queen’s University Belfast (QUB) with just that aim, using long-haul trucks.

Initiated by Prof Roy Douglas and Dr Stephen Glover and led by Dr Kevin Morgan, the project is trialling a dual-fuel truck, where most of the diesel is substituted with natural gas, to show whether Northern Irish hauliers can use this technology in the ‘real world’.

“Natural gas burns clean with no particulates and contributes no net carbon emissions to the atmosphere in the form of biomethane,” said Morgan, describing the potential impact to the environment. “In our trial, 60pc of the diesel used by the truck is substituted for natural gas.”

Morgan told me he’s testing the technology with a haulier in Co Tyrone. A large truck transports milk to a creamery from individual farms in a 400km round trip.

“Currently, in Ireland, refuelling is an issue. There’s a lack of rapid-fill compressed natural gas filling stations, with the only two being in Dublin and Cork. So there are supply-side problems,” said Morgan.

“Our trial is crucial to showing transporters that this technology is a cost-saving, environment-saving change. Then we hope to persuade our politicians that building refilling stations is a critical part of our renewable energy mix.”

Dual fuel

I asked Morgan if there are any dual-fuel trucks operating commercially in Northern Ireland yet. “Not that we’re aware of,” he said.

‘Currently, in Ireland, refuelling is an issue. There’s a lack of rapid-fill compressed natural gas filling stations’

Morgan described how the two fuels create a synergy: “Diesel ignites at a lower temperature, so when both fuels are injected together, the diesel helps to ignite the natural gas.”

He also explained the cost savings to the haulier: “The cost per kilowatt-hour is halved. Presently, the cost of diesel sits around 10p per kWh and natural gas is 5p per kWh. That equates to a saving of around 20 to 30pc on fuel costs, when 60pc of the fuel is substituted.”

This technology is already widely used in Scandinavia, Germany, the US and beyond. So Northern Ireland is behind the curve, and this project is about proving its viability here.

The good news? The future of dual-fuel hauliers can run even cleaner, if biogas produced by Northern Ireland’s anaerobic digestion plants is used.

“We get a lot of interest from hauliers but we need to convince Stormont,” said Morgan. “We’re asking for a culture change. People are used to diesel, but dual fuel is attractive because it comes with 100pc diesel fallback.”

‘We get a lot of interest from hauliers but we need to convince Stormont’

According to Morgan: “Dual fuel is seen as the starting point to the ignition of lean methane mixtures that have significant potential to reduce vehicle carbon emissions.”

The next step in their research is to focus on burning methane ‘successfully’ at a leaner air-to-fuel ratio with resulting low emissions of mono-nitrogen oxides. “[That] is a technology milestone that QUB are working towards,” said Morgan.

To develop an accompanying after-treatment, a high-profile research project is underway with Douglas and Prof David Rooney.

Waste heat recovery

From the Department of Mechanical and Aeronautical Engineering, and also under the direction of Douglas, Glover manages ongoing projects in the area of waste heat recovery and ORC (Organic Rankine Cycle) engines.

“The potential double-bang of clean transport is using a fuel like biomethane in a lean-burn condition in a diesel cycle, and having a waste heat recovery system that converts heat to electricity,” said Glover.

The area of waste heat recovery that Glover researches involves “supercritical cycles”. He told me: “These systems operate above the critical point of fluid high pressure. We’re looking at generating electricity through high-expansion ratio expanders, expanding vapours at supercritical pressures and 150 to 300 degrees Celsius.”

The research is conducted via designs. “We use simulation model-based design to guide us in the thermodynamics and fluid mechanics of the physical systems, and then test to validate the prototype expanders,” said Glover.

“We’re testing systems with aluminium and steel components, using model simulations to perfect the design. As the design iterations mature, we will involve more complex and cost-effective materials to drive down weight and cost.”

‘We’ve put 15 years of research into reciprocating expander technology’

This project has been running for well over a decade. “We’ve put 15 years of research into reciprocating expander technology,” said Glover. “We have two prototype systems that will be tested in Bridge Energy, as part of a [CASE] project and of the new QUB Pioneering Research Programme in sustainable energy.

“By the end of 2017, we will have an ORC [waste heat recovery] circuit attached to an engine in QUB’s David Keir building that will reduce QUB’s carbon footprint, albeit at a smaller scale. But this first pilot plant will also serve as a teaching platform for students. It will produce QUB’s own electricity from waste heat, paving the way for larger-scale plants, and all home-grown in NI for local impact,” said Glover.

This teaching facility is a ‘living lab’, which is all about getting future engineers to physically work with the technology. Glover said: “ORC has the potential to double the fuel economy of vehicles.”

By Emily McDaid, editor, TechWatch

A version of this article originally appeared on TechWatch

TechWatch by Catalyst covered tech developments in Northern Ireland