Waste heat recovery: introductory guide

1. Introduction

1.1 Aims of this guide

The UK and Scotland is transitioning to a low carbon energy system. This will require making better use of the energy we have.

The aim of this guide is to provide information about heat that is being wasted or not used to its full potential and how to capture it and use it. This includes facilitating better communication and understanding between relevant parties interested in providing and using waste heat. Ultimately, this is to encourage reuse, thus reducing energy consumption and carbon emissions whilst also possibly delivering commercial benefits.

The guidance is directed at non-technical specialists. The goal is to develop knowledge that will enable them to engage with third parties, such as waste heat producers and heat network operators, on the topic of waste heat. This engagement should ascertain if organisations have any initial, high level interest in offering their waste heat and identify potential options for its use.

1.2 Context

1.2.1 What is waste heat recovery?

Waste heat recovery is a process of capturing and utilising heat from industrial and commercial processes, or similar activities, which may otherwise be lost. The recovered heat can be used in a range of applications, including heat networks.

1.2.2 Drivers for providing guidance now

There are several drivers for making better use of waste heat in Scotland:

• Scotland’s local authorities are in the process of completing their Local Heat and Energy Efficiency Strategies (LHEES), which are fifteen-to-twenty-year strategies for decarbonising heat across each authority’s area^[1].
• The 2021 Heat Networks Act (Scotland) gives powers to local authorities to designate heat network zones and sets statutory targets for heat to be supplied by heat networks – 2.6 TWh by 2027, 6 TWh by 2030 and 7TWh by 2035^[2].
• The Scottish Government is supporting a growing pipeline of heat network projects with £300 million of capital funding available through Scotland’s Heat Network Fund to accelerate deployment^[3].
• Previous research by ClimateXChange for the Scottish Government identified over 900 sites in Scotland producing waste heat, totalling 1.7 TWh that could potentially be reused ^[4].

The combination of national heat network targets and investment, the number of sources and scale of waste heat potentially available, and the work being done by local authorities to identify indicative Heat Network Zones (HNZ), collectively make a strong case for investigating opportunities for linking waste heat with heat networks more systematically.

Historically, heat networks have been largely unregulated compared to gas and electricity, but things are changing. The Heat Networks (Scotland) Act 2021 was the first legislation implemented in the UK in support of the heat networks sector^[5]. The Act is anticipated to create the stability needed to unlock the potential of heat networks in Scotland, enabling the sector to grow at pace and make a valuable contribution to the energy transition and Net Zero. The Scottish Government is working with the UK Government and Ofgem to ensure that regulations, such as those regarding consumer protection and technical standards, are interoperable.

At regional scale, the creation of LHEES is enabling local authorities to identify opportunities for potential heat network zones. Although formally designating heat networks zones falls beyond the scope of LHEES, the powers for heat network zoning came into force in May 2023 and further proposals for Scottish legislation are being phased in to ensure a seamless experience for heat network operators and offtakers ^[6],[7].

At local and building scale, heat networks are a critical component of Scotland’s Heat in Buildings Strategy^[8]. This requires, for example, non-domestic, publicly owned buildings with a heat demand equal to or greater than 73 MWh/year to produce a Building Assessment Report (BAR). A BAR contains information on the heat supply and demand of the building and assesses its suitability to connect to a heat network. This is important because it provides key information about the feasibility of a heat network in a potential heat network zone.

1.2.3 Origins of the guidance

The need for this guidance document was identified by the ‘Waste Heat from Industry’ Steering Group, which was established by Scottish Enterprise and comprises:

• The Scottish Government (SG)
• Scottish Environment Protection Agency (SEPA)
• Zero Waste Scotland (ZWS)
• Scottish Futures Trust (SFT)
• Glasgow City Council (GCC)
• Fife Council (FC)