Nanostructured half-Heuslers for thermoelectric waste heat recovery

Lead Research Organisation: Heriot-Watt University
Department Name: Sch of Engineering and Physical Science

Abstract

Thermoelectric materials convert waste heat into useful electric power. Even inefficient thermoelectric power generation recovery can have a substantial impact on UK and global energy consumption because more than half of primary energy is ultimately wasted as heat. So far, thermoelectric generators (TEGs) have been restricted to niche applications, such as powering the Voyager space probes, where durable, reliable and low-maintenance power generation is essential. However, the market for thermoelectric energy harvesters is projected to approach $1bn within a decade.* Potential applications for TEGs include scavenging heat from car exhausts, producing combined heat and power units for use in remote, off-grid locations, and replacing batteries in wearable microelectronic devices. A major limitation has been to develop cheap, efficient TEGs that do not rely on toxic or scarce resources. For example, the most efficient thermoelectric material for automobile heat recovery is currently a compound of toxic lead and scarce tellurium.

In this project, we aim to develop a viable, non-toxic alternative to lead telluride TEGs, using 'Heusler alloys', which combine abundant elements such as titanium, nickel and tin. They also meet the majority of industrial requirements for thermoelectric power generation, having good thermal and mechanical stability, mechanical strength and ease of processing. However, a TEG's thermal conductivity is also critical and optimising the thermal conductivity of Heusler alloys has been problematic. We aim to capitalise on our recent advances in Heusler alloy synthesis and nanostructuring, which currently represents the only UK efforts in this fast-growing field.

The ultimate aim of this proposal is to develop new means of controlling the thermal conductivity of Heusler alloys in order to build a TEG prototype of comparable performance to existing lead telluride devices. Our insight is that there are a variety of alloy phases and intentional defects that can be used to introduce structural texture on the nanoscale, thereby reducing the thermal conductivity. What is exciting is that many of these structures have not previously been studied. A critical aspect is the size and distribution of the texturing, which should be long enough to avoid reducing the material's electrical conductivity but short enough to impede the flow of heat. We will investigate the optimum length-scales for texturing by performing a systematic study of the impact of processing conditions on the HA nanoscale structure. We will use world-leading electron microscopy, neutron scattering facilities and theoretical modelling to probe the atomic-scale structure and dynamics of the new materials in order to optimise the synthesis parameters. We will then use this technical know-how in collaboration with our industrial partner European Thermodynamics Ltd. to build prototype TEG modules.

This collaborative project, involving three academic institutions, national facilities and a UK small business, has substantial potential for impact, with notable prospects for making a contribution to lowering the UK's carbon footprint. It also provides excellent opportunities for knowledge transfer to a vibrant new industry and for high-quality training.

* H. Zervos, "Thermoelectric Energy Harvesting 2014-2024: Devices, Applications, Opportunities," 2014

Planned Impact

WHO?

Our principal impact lies in the development of KNOWLEDGE: through the discovery, synthesis and analysis of new nanocomposite Heusler alloys; through the study of alloy stability and dynamics; and by addressing the practical aspects of constructing a viable prototype device.

We aim to develop an energy harvesting technology that will contribute to efforts to reduce the UK's carbon footprint, for example, by improving the fuel efficiency of cars. There is therefore substantial prospect of SOCIETAL IMPACT, both through the development of energy-efficient technologies and through a reduction in the use of scarce and toxic elements.

PEOPLE IMPACT: The training opportunities are substantial, benefitting the 'pipeline' of highly skilled researchers required for our knowledge economy. The research associates working on the project, PhD students working in our groups, and students enrolled on Masters-level and doctoral level taught programmes will benefit from the research. In addition, we identify a number of academic beneficiaries.

ECONOMIC IMPACT: Perhaps the most important impact is via industrial engagement. We are actively collaborating with an industrial SME partner, European Thermodynamics Ltd., with the intention of developing a thermoelectric generator that would be suitable for high-volume production in a market that is not currently covered well in the UK.

HOW?

We will use traditional dissemination activities of publications, workshops and conference contributions to engage with the wider academic community. We have identified specialist conferences with a focus on energy materials, in addition to more general meetings spanning materials, microscopy, etc. These will be augmented by new collaborations, facilitated by visits to other institutions and facilities, inward and outward invited talks, etc.

We will continue to engage with the EPSRC-funded TEMPEST network, which acts as multidisciplinary hub for thermoelectric researchers and industrialists across the UK, and provides an ideal mechanism for maintaining and growing collaborative links with the leading researchers and industrialists in the field.

We will collaborate with our SME partner, European Thermodynamics Ltd., in order to translate our research into the industrial laboratory. The materials discovery and characterisation aspects of our proposal are beyond the capabilities of ETL, making the collaboration of extremely high interest to them. Through this partnership, we will also aim to inform a non-academic, industrial audience by disseminating results at trade shows and in trade magazines.

In accordance with the policy of research-led teaching at the host universities, we will incorporate results into teaching material suitable for postgraduate lecture and laboratory classes. Energy efficiency as a theme is particularly suited to classroom discussion.

We will inform our outreach activities by results derived from the project; as above, the research theme is easy for the public to engage with. The investigators have experience in presenting to the general public, for example, at Science Festivals, and the proposed research will be very accessible to a wide audience. Heriot-Watt will host a dedicated website to disseminate our research aims and non-confidential results to the wider public.

Heriot-Watt University and the University of Glasgow are both signatories of 'EasyAccess IP' (http://www.easyaccessip.org.uk/), a fast-track route for knowledge transfer that aims to develop any commercial benefits of our research for the benefit of the economy and society. We will maintain this approach for any IP generated during the project and will enlist the help of our research and enterprise offices to assist with Knowledge Transfer activities.

We will explore possibilities for follow-on funding including, for example, Knowledge Transfer Partnership funding, should this be appropriate.

Publications

10 25 50
 
Description We have discovered viable thermoelectric performance in the n-type half-Heusler TiNiCuySn, which contains only abundant elements. We have spent significant effort in working up protocols for the detailed structural characterisation of these materials so that their properties can be modeled by physicists. This involves combining multiple techniques and will set the standard in the field. In case of the TiNiCuySn materials, this revealed that their properties are dictated by randomly distributed Cu atoms and not by nanoinclusions, which is a deviation from the accepted paradigm. Our industrial partner, European Thermodynamics Ltd is currently working on the electrical and thermal contacting and applying the TiNiCuySn materials in prototype power generation modules.
Exploitation Route We have provided new scientific insights in half-Heusler thermoelectric materials. These will be of use to other researchers working in this field and will aid further improvements in efficiency. In collaboration with our industrial partner we are trying to resolve some of the up-scaling and engineering issues associated with application of these materials in devices.
Sectors Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Other

 
Description European Thermodynamics Ltd. has used the project to assist the materials discovery aspects of their own research and development programme. They have taken upscaling and prototyping of the HH compositions further through BEIS Early Stage Energy Catalyst Funding in a project that also involves Johnson Matthey. In addition, a number of outreach activities have been undertaken, notably our participation at major events held at the Glasgow Science Centre, where we have contributed an interactive presentation that has engaged members of the public across the entire age range. Both Heriot-Watt and Glasgow investigators have given Pint of Science Talks on thermoelectric waste heat recovery to the general public.
Sector Education,Energy,Culture, Heritage, Museums and Collections
Impact Types Societal,Economic

 
Description Hall measurements 
Organisation Northumbria University
Country United Kingdom 
Sector Academic/University 
PI Contribution Development of novel half-Heusler thermoelectric materials, on which we undertook Hall measurements at Northumbria University.
Collaborator Contribution Hall measurements to obtain carrier concentration and mobility of thermoelectric materials prepared at Heriot-Watt University.
Impact Collaboration will result in joint publications and will aid materials exploration programme
Start Year 2017
 
Description Oxford Atom Probe Group 
Organisation University of Oxford
Department Atom Probe Research Group
Country United Kingdom 
Sector Academic/University 
PI Contribution Time offered on Glasgow PFIB instrument as part of new access arrangements established as part of the funding.
Collaborator Contribution In-kind 'beam-time' on the Oxford 3DAP instrument.
Impact Joint conference presentations.
Start Year 2017
 
Description Explorathon Glasgow Science Centre (30 September 2016) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We had a stand at the Glasgow Explorathon European Researchers' Night. This was well attended by members of the public of all ages. Our stand covered the thermoelectric materials research funded by the grant. We increased awareness of this technology, which is less well known than photovoltaics. Very good response, in particular to the use of bodyheat to generate electricity. The stand was mix of printed information and simple demonstrators that brought the technology to life.
Year(s) Of Engagement Activity 2016
 
Description News Article in the The Chemical Engineer 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact News article in the online edition of The Chemical Engineer Magazine. Published by the Institution of Chemical Engineers. Phone interview was written up in to news article. This covered the proposed research of the grant.

https://t.co/iYPVXfqe9P
Year(s) Of Engagement Activity 2016
URL https://t.co/iYPVXfqe9P
 
Description News Article in the The Engineer UK 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact News article in the online edition of The Engineer UK. (www.theengineer.co.uk). Phone interview was written up in to news article. This covered the proposed research of the grant.

https://t.co/XBg3hXxB5g
Year(s) Of Engagement Activity 2016
URL https://t.co/XBg3hXxB5g
 
Description Radio interview with Peter Warren from Future Intelligence on Resonance FM 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Radio interview with Peter Warren from Future Intelligence on Resonance FM. Discussed thermoelectric waste heat recovery, and our EPSRC funded research.
http://www.futureintelligence.co.uk/fis-password-radio-show/
https://resonancefm.com/
Year(s) Of Engagement Activity 2016
 
Description Talk at Pint of Science in Edinburgh 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Invited talk at the 2018 Pint of Science Festival on "Electricity generation from waste heat using thermoelectrics" to a general audience (30-40 people) at the Cannon's Gait venue in Edinburgh on the 14th My 2018. The talk one of two in the Finding Worth in Waste Session. Main outcome was wider dissemination of the existence of thermoelectric energy recovery, which unlike solar renewable energy is less widely known.
Year(s) Of Engagement Activity 2018
URL https://pintofscience.co.uk/event/finding-worth-in-waste
 
Description Thermoelectric Network UK Meeting 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact invited research talk entitled "Multi-length Scale Characterisation of Half-Heusler Thermoelectrics" to UK forum on thermoelectrics. The audience was primarily academic researchers but also included industrialists with interests in the research field. The aim of the forum was disseminate recent research advances, including materials discovery. After the talk, other delegates requested further information on the materials described and on the techniques used to prepare them, most notably the use of our PFIB instrument. Some delegates expressed an interest in making use of our equipment.
Year(s) Of Engagement Activity 2017
URL http://www.thermoelectricnetwork.com/