The role of thermal energy in global energy transition

Thermal Energy 1

By Associate Professor Jundika Candra Kurnia

As the world population surges to 8.1 billion, global energy demand is skyrocketing, driven by rapid industrialisation, particularly in economic giants like China and India. Today, much of this demand is met by fossil fuels, with renewable sources such as solar, wind, and hydropower slowly making their mark.

However, our deep dependence on fossil fuels is exacting an enormous toll on the planet. The environmental consequences are grim: air and water pollution, greenhouse gas emissions fuelling climate change, and ecosystem destruction. Moreover, fossil fuel prices are on a relentless upward trajectory due to dwindling supplies and geopolitical constraints. Simply put, our reliance on fossil fuels is both unsustainable and harmful, and it is time for a radical change.

The global community has heard the call for a cleaner, more sustainable future. In response to the escalating environmental and economic challenges posed by our heavy reliance on fossil fuels, there is mow a global imperative for an energy transition. The urgency is underscored by the fact that the current trajectory is unsustainable, given the finite nature of fossil fuel resources and their detrimental impact on the planet.

The Paris Agreement, a landmark international accord, has laid the foundation for a concerted effort to shift towards cleaner energy sources and mitigate climate change, and many nations have responded by increasing investments in solar, wind, and hydropower, to reduce their heavy reliance on fossil fuels and at the same time diversify their energy mix.

These investments are not just about the environment; they are about energy security, ensuring future generations have access to reliable and locally sourced energy. Yet, while the spotlight has been on electricity generation, mainly solar PV, wind energy, and hydropower, an essential piece of the energy puzzle has been neglected: thermal energy.

Thermal Energy 2

Thermal energy is everywhere – powering industrial processes, heating homes, and running essential infrastructure. Yet, the conversation around renewable energy has largely centred on electricity, leaving thermal systems out in the cold. It is inefficient to use high-grade energy like electricity to meet low-grade thermal demands when renewable thermal solutions could step in. To truly revolutionise our energy systems, we must shift our focus to renewable thermal energy.

Imagine harnessing the sun’s power to provide heat for industries, tapping into the Earth’s geothermal reserves for continuous energy, or even using ocean temperatures to drive power plants – these are all achievable with renewable thermal systems.

Solar thermal, geothermal, ocean thermal, and biomass technologies present significant opportunities for reducing our dependence on fossil fuels in sectors that require heat rather than electricity. These technologies are not just environmentally friendly; they offer consistent, reliable energy solutions that can operate at scale.

Success stories of renewable thermal energy are emerging across the globe, showcasing the potential for large-scale change. For instance, Germany achieved an impressive solar thermal capacity of 1,500 MWth in 2008, equivalent to an area of 2.1 km² of solar collectors. While this capacity dipped in subsequent years as investors favoured solar PV, recent rebounds demonstrate renewed interest in solar thermal energy.

Geothermal energy is another promising player, which is constantly increasing and is predicted to keep growing at annual growth rate of 4.10 per cent. The total global  capacity of geothermal reached 16,335 MW at the end of 2023 with countries like the United States, Indonesia, and the Philippines leading the charge. Geothermal electricity is expected to generate nearly 100 billion kWh in 2024.

Similarly, ocean thermal energy conversion (OTEC) holds massive potential, with global capacity forecasts as high as 107 PWth/year. When installed at capacities of more than 120 MWgross, some OTEC plants offered attractive Levelised Cost of Electricity (LCOE) below 15 US¢/kWh (2021 USD value) in some regions. Hawaii’s Makai OTEC power plant, the largest of its kind, powers 120 homes, and larger-scale plants are on the horizon.

Even biomass energy, often overshadowed by other renewables, boasts a global capacity of 148.912 GW, with China and Brazil leading the way. These success stories prove that renewable thermal energy is not just viable –  it is essential. Unlike solar PV and wind, which are often geographically concentrated, thermal energy technologies have the advantage of being more evenly distributed, giving more countries access to sustainable thermal energy solutions.

So, why isn’t renewable thermal energy in the limelight? The answer lies in our over-reliance on electricity-centric solutions and the lack of investment in alternative thermal technologies. It is time for a paradigm shift. By expanding our focus to include renewable thermal energy systems, we can create a more balanced and resilient energy transition – one that addresses both our electricity and heating needs.

Governments, industries, and research institutions must prioritise thermal energy technologies and invest in their development. This investment will not only reduce greenhouse gas emissions but also combat the resource depletion and environmental degradation caused by conventional thermal processes.

Creating a fair energy ecosystem is key. Renewable thermal energy technologies need equal footing with electricity generation in policies, incentives, and market access. Only by levelling the playing field can we unlock the full potential of renewable energy in its many forms and ensure a sustainable future for all.

In this broader vision, renewable thermal energy emerges as the unsung hero of the global energy transition, offering innovative solutions that go beyond just electrification. It’s time to give it the recognition it deserves and embrace a truly holistic approach to energy.

Jundika Candra Kurnia is an Associate Professor in Mechanical Engineering and Head of the Energy and Environment Research Cluster at Curtin University Malaysia’s Faculty of Engineering and Science. He was formerly a Senior Lecturer in Mechanical Engineering and Head of the Research Centre (GHTeC/STARC at Universiti Teknologi PETRONAS (UTP). With over 15 years of Research & Development and academic experience, Dr. Kurnia is a highly regarded expert in renewable energy, holding credentials as a Chartered Engineer (UK), Professional Technologist (Malaysia), and Senior Professional Engineer (Indonesia). He has published extensively, secured competitive national and international grants, and serves as an advisory board member, visiting professor, invited speaker, and journal guest editor. Dr. Kurnia can be contacted at jundika.kurnia@curtin.edu.my or jundika.kurnia@curtin.edu.au, or by phone at +60 85 630100 Ext: 2517.