Innovation Exchange challenge: Enhanced thermally conductive backfill for underground HV cables

Entrants to this competition must be:

• Established businesses, academic institutions, start-ups, SMEs, or individual entrepreneurs
• UK based or have the intention to set up a UK base

Applications will be assessed on:

• Relevance to the defined challenge
• Benefit of implementation
• Feasibility/economic viability
• Innovative nature
• Ability to launch in line with expected timescales
• Credibility of applicant company
• Coherence of the proposed business model
• Development potential
• Maturity of the solution
• Suitability for the intended geographic market

Academics and RTO’s are encouraged to include or identify potential commercialisation partners or, as a minimum clearly identify the commercialisation route.

Omexom Taylor Woodrow are seeking solutions that can specifically address:

• Derisking the availability of suitable sand
• Reducing the net carbon footprint
• Less denuding of natural resources
• Improving cost certainty

And can also address:

• Improving backfill thermal conductivity to reduce the excavation needed and sand imported and/or enable improved rating of underground HV cables
• Reducing the commercial risk of availability from local quarries
• Avoiding the potential need to take surplus excavated materials offsite

This may include and is certainly not limited to solutions that:

• Utilise additives and/or processes that uplift the conductivity of currently unsuitable sands
• Blend unsuitable soils with high conductivity minerals such as metal salts
• Utilise mine tailings and historic mining spoil
• Utilise high conductivity waste streams such as ceramics waste or suitable demolition materials
• Valorise excavated materials on site to enable use in CBS
• Utilise novel additives that permanently sit within the sand matrix to enhance heat transfer between grains (similar to the effect of water saturation but not sensitive to draining or drying)
• Offer different systems of materials and processes that accomplish the end goal of cables within ducts in a protective, conductive medium or otherwise providing heat dissipation
• Have nationwide availability (ideally within 40 mile radius of project sites)

It is recognised that solutions are likely to require development and thena rigorous National Grid complaince activity.  A timeline of under 18 months to compliance trials with National Grid is proposed; naturally a faster programme would be highly desirable. This aligns to an expectation of commercial readiness at large scale under 4 years.

More developmental solutions that may struggle with this timeline are also welcome if they offer very strong potential.

Your proposal should clearly identify your current maturity and the estimated timeline to readiness for National Grid compliance testing.

Functional Requirements

1. The solution must be able to be practicably placed insitu, under, around and over cable ducts, so that the target thermal conductivity can be assured; this is likely to entail controlled compaction. The minimum CBS surround thickness is 75mm
2. Currently the thermal conductivity is not measured insitu, instead density is simply measured to determine the void content. If this technique is not appropriate to the solution an effective insitu measurement technique should be identified. (For general guidance of site quality control expectations please see ENA TS 97-1)
3. Be compatible with and in no way deleterious to PVC ducting
4. Be compatible with cement binder and compatible with lime, emergent AACM geopolymers and common cement replacement materials
5. Not cause harm or change to the natural ground (that is often arable land) or watercourses through leaching or other mechanisms- depending upon the potential harm a protection system could be considered
6. Be no more hazardous to work with than current cement bound sand (CBS)
7. Cure to a reasonably hard material to protect the cables from mechanical damage
8. Be available at a sufficient assured scale (please specifically confirm this aspect within your submission)
9. The expectation is for the sand to have negligible clay particles (typically less than 0.06mm) so that it is not overly sensitive to volumetric changes due to heating, cooling or water events.

Technical Requirements

1. Design life in excess of 40 years without degradation
2. The solution must achieve a (dry) thermal resistance of less than 1.2K.m/W
3. And should ideally achieve a (dry) thermal resistance of less than 1.0K.m/W
4. The solution must be structurally competent and reliable so able to withstand reasonable compressive load once cement bound and consolidated.
5. The solution must not contain any particles exceeding 5mm (95% to pass 5mm sieve)
6. The solution should have consistent resistivity from 0 to 110ºC
7. The solution must not increase in thermal resistivity from 70 to 110ºC

Operational requirements

The solution should:

1. Not be limited in processing, placing and compaction by UK weather such as wind and rain, extreme cold excepted which would equally restrict the use of CBS.
2. Not be vulnerable in use when exposed to the range of UK weather including permeation from rain, water courses and groundwater.
3. With the addition of cement binder be able to be placed and be stable at a batter of 2:1 from the horizontal

The solution has the potential for deployment of approximately 33km of underground cables within the OTW contracts alone.

Successful applicants will be given the opportunity to pitch to Omexom Taylor Woodrow.

Selected solutions can benefit from collaborative support from Omexom Taylor Woodrow to develop their solution through expert input, characterisation testing and physical trials in a safe environment. From this it is likely that more substantial funding will be needed to prove suitability to National Grid. This could be through the Network Innovation Allowance (NIA) funding secured through collaborative partnership with Omexom Taylor Woodrow.

The benefits package for a successful applicant may also include:

• Support from Innovate UK Business Connect
• Support in the development of a prototype or pilot
• Technical support
• Invitation to attend or present at Innovate UK Business Connect events
• A potential business collaboration
• Investor introductions (if investment is required)

Support if any Innovate-UK or similar competitions are relevant.

• Launch: Wed 19th November 2025
• Closing date: Monday 19th January 2026
• Review Meeting: Monday 26th January 2026
• Notification Date: Tuesday 3rd February 2026
• Pitch days: Tuesday 24th February and Wednesday 25th February in Castleford