Capturing and utilizing natural and waste heat is nothing new. Long before modern heat pumps and industrial recovery systems, civilizations across the world found clever ways to harness thermal energy – whether from volcanic springs, fire-heated floors, or even bustling sewers.

In 2025 capturing and utilizing natural and waste heat is now not only used as a solution to enhance energy efficiency, but also to reduce greenhouse gas emissions, and offer a sustainable energy solution.

Under natural heat we understand heat derived from geothermal or solar thermal sources. Waste heat on the other hand is a byproduct of (industrial) processes. According to the International Energy Agency (IEA), industrial waste heat could meet up to 20% of global industrial energy demand, potentially avoiding hundreds of millions of tons of CO2 emissions annually. Similarly, geothermal energy powers nearly 90% of Iceland’s heating needs with near-zero operational emissions.

Simple? Not really, despite the benefits, we are confronted with technical, economic, and – of course – regulatory hurdles which impede widespread adoption.

In this article I’m going to explore the sustainability benefits of heat capture and the obstacles to scaling its implementation.

The Sustainability Potential of Heat Capture

Understanding Natural and Waste Heat

  • Natural Heat: This encompasses geothermal energy, harnessed from the Earth’s internal heat, and solar thermal energy, captured from sunlight to heat fluids for residential, commercial, or industrial use. Geothermal systems are particularly effective in geologically active regions, while solar thermal systems are versatile for applications like water heating.
  • Waste Heat: This is thermal energy generated as a byproduct of industrial processes, power generation, or infrastructure like data centers. The U.S. Department of Energy (DOE) estimates that industrial facilities account for 32% of total U.S. energy consumption, with a significant portion lost as waste heat.

Capturing these heat sources and repurposing them for electricity generation, heating, or industrial processes of course aligns with the principles of a circular economy, reducing waste and maximizing resource efficiency.

Data on Natural and Waste Heat Capture

Harnessing natural and waste heat is a cornerstone of sustainable energy strategies, offering important potential to reduce emissions, enhance efficiency, and drive economic savings. To provide a clear, evidence-based perspective on this topic, the following data tables compile verified metrics from recent studies and authoritative sources, including the International Energy Agency (IEA), McKinsey, and the U.S. Department of Energy.

In these tables I quantified the global and regional impacts of waste heat recovery (WHR), the efficiency of geothermal energy applications, and the performance of key WHR technologies. They offer concise insights into energy savings, emissions reductions, and technological capabilities, supporting informed decision-making for businesses, policymakers, and sustainability advocates.

Global Waste Heat Recovery Potential and Impact

Estimated energy and emissions savings from waste heat recovery across industrial sectors, showing its sustainability potential.

Metric Value Source
Global Industrial Energy Consumption 418 exajoules (EJ) annually McKinsey, 2023
Waste Heat Loss (Global) 20-50% of industrial energy input U.S. Department of Energy
Feasible Waste Heat Not Captured 3,100 thermal terawatt-hours (TWhth) McKinsey, 2023
Potential CO2 Emissions Reduction Hundreds of millions of tons annually IEA, 2023
Economic Savings from WHR €140 billion annually McKinsey, 2023
India-Specific CO2 Emissions Reduction 150-180 million tons by 2030 EAI, India

Geothermal Energy Applications and Efficiency

Below are the key metrics on geothermal energy’s contribution to sustainable heating and electricity, with global and regional examples. Note that geothermal energy is highly effective in specific regions like Iceland and shows enormous potential for emissions and cost savings in the U.S. through heat pumps.

Application Metric Value Source
Geothermal Heating (Iceland) Percentage of National Heating 90% EEA, 2023
Geothermal Electricity (Iceland) Percentage of National Electricity 25% EEA, 2023
U.S. Geothermal Heat Pumps Potential Carbon Emissions Avoided by 2050 7 gigatons of carbon-equivalent ORNL, 2024
U.S. Geothermal Cost Savings Energy Cost Savings by 2050 $600 billion ORNL, 2024
Global Geothermal Plant Efficiency Typical Thermal Efficiency 10-20% (for electricity generation) IntechOpen

Waste Heat Recovery Technologies and Efficiency

In this table I collected common WHR technologies, their applications, and efficiency metrics for industrial processes. It’s important to know that ORC and Kalina cycles are effective for low-grade heat, while heat exchangers and TES offer versatile solutions for industrial applications.

Technology Application Efficiency/Savings Source
Organic Rankine Cycle (ORC) Electricity generation from low-grade heat Up to 20% thermal efficiency MDPI, 2025
Heat Exchangers Process heating, preheating 50-80% heat recovery rate Sigma Thermal, 2024
Regenerative Burners Industrial furnaces 15% fuel savings PMC, 2023
Thermal Energy Storage (TES) Store heat for later use Up to 90% storage efficiency Stellarix, 2025
Kalina Cycle Low-temperature heat to power 10-15% higher efficiency than ORC IntechOpen

Sustainability Benefits of Natural and Waste Heat

Now that we know the data behind natural and waste heat capture, it’s also key to understand what the sustainable benefits are.

  1. Enhanced Energy Efficiency:
    • Waste Heat Recovery (WHR): Globally, over 418 exajoules (EJ) of final energy is consumed annually, with a substantial portion lost as waste heat. Recovering this heat can significantly improve system efficiencies. Combined heat and power (CHP) systems achieve efficiencies of 80-90%, compared to 30-50% for conventional power plants.
    • Case Study: A 2023 study on a slab-type heating furnace with regenerative burners reported a thermal efficiency of 72%, achieving 15% fuel savings compared to conventional systems. Similarly, Nestlé’s use of GEA’s heat recovery system in its spray drying equipment generates 80°C hot water, reducing energy consumption and emissions.
  2. Significant Emission Reductions:
    • WHR reduces reliance on fossil fuels, lowering CO2 and other greenhouse gas emissions. The IEA estimates that capturing waste heat could avoid hundreds of millions of tons of CO2 emissions annually by offsetting industrial energy demand.
    • Geothermal energy produces near-zero operational emissions. A 2024 study by the National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL) found that installing geothermal heat pumps in ~70% of U.S. buildings could avoid 7 gigatons of carbon-equivalent emissions by 2050.
    • Example: Denmark’s district heating systems, which use waste heat from power plants, have helped Copenhagen target carbon neutrality by 2025.
  3. Economic Savings:
    • McKinsey estimates that global waste heat recovery could save up to €140 billion annually, comparable to the value of EU natural gas imports in 2021. These savings arise from reduced fuel costs and improved operational efficiency.
    • Case Study: Smithfield Foods’ heat recovery system for refrigeration compressors saved over 100,000 MMBtu annually, significantly reducing natural gas consumption.
  4. Environmental and Social Co-Benefits:
    • WHR reduces emissions of pollutants like NOx, SOx, and particulate matter, improving air quality and public health, as noted in a sustainability analysis. For example, the SELCHP waste-to-energy facility in London uses waste heat to power electric refuse vehicles, creating jobs and reducing emissions.
    • Geothermal systems enhance energy security by leveraging local resources. Iceland’s geothermal infrastructure has made it nearly self-sufficient in heating energy, reducing reliance on imported fuels.
  5. Urban and Industrial Applications:
    • Data Centers: Facebook’s data center in Odense, Denmark, channels waste heat to warm nearly 7,000 homes, potentially reducing emissions by 10 million tons of CO2 annually if scaled to larger regions.
    • Industrial Sector: The cement industry, operating at temperatures up to 400°C, uses WHR systems like GEA’s XECO® to recover heat from kiln flue gases, supporting both energy efficiency and carbon capture integration.

Real-World Success Stories

The proof of the pudding is in the eating of course. We can only judge these ideas by trying it out. After all, results matter more than claims. Below you can find 3 real-world success stories where natural and waste heat is effectively used.

Iceland’s Geothermal Leadership: Iceland generates 25% of its electricity and 90% of its heating from geothermal sources, with emissions from its energy sector among the lowest globally.

Copenhagen’s District Heating: Copenhagen’s district heating network, powered by waste heat from power plants and incinerators, supplies 98% of the city’s buildings, contributing to its goal of carbon neutrality by 2025.

Industrial WHR: ROWI’s installation of ELGi air compressors with heat recovery systems in 2025 reduced energy consumption by reusing compressor heat for production space heating.

These examples are all backed by data, and demonstrate the tangible impact of heat capture in diverse contexts.

Hurdles to Adoption: Evidence-Based Challenges

Despite its potential, heat capture still faces several barriers, as documented in recent studies. Ignoring these issues serves no purpose – they will need to be addressed sooner or later, whether through technology, regulation, or other targeted solutions.

1. Technical Challenges

  • Infrastructure Complexity: Capturing and distributing heat requires advanced equipment like heat exchangers, organic Rankine cycle (ORC) systems, or thermal storage units. A 2023 study highlights challenges in integrating these into existing processes due to space constraints and process compatibility.
  • Heat Quality: Much waste heat is low-grade (<100°C), limiting its applications. Converting low-grade heat to electricity requires ORC systems, which remain expensive despite cost reductions through modularization.
  • Transport Limitations: Heat loses energy over long distances, necessitating proximity between sources and users, as noted in a district heating analysis. This constraint complicates projects in rural areas.
  • Storage Issues: Seasonal variations in heat demand require effective storage solutions. While large-scale thermal storage is cost-efficient compared to batteries, it remains underdeveloped.

2. Economic Barriers

  • High Capital Costs: Installing WHR or geothermal systems involves significant upfront investment. For example, geothermal well drilling can cost millions, and retrofitting factories for WHR requires costly equipment.
  • Long Payback Periods: Payback periods can span years, especially in regions with low energy prices. A 2022 study notes that economic viability depends on energy market fluctuations and carbon pricing.
  • Competition with Fossil Fuels: Subsidized fossil fuels in some markets make renewable heat systems less competitive, as highlighted in policy discussions.

3. Regulatory and Policy Barriers

  • Lack of Incentives: Many regions lack subsidies or tax credits for heat capture technologies. A 2023 analysis recommends favorable policies to encourage WHR adoption.
  • Permitting Delays: Geothermal projects face lengthy permitting processes due to environmental and land-use concerns, as noted in geothermal studies.
  • Inconsistent Standards: Fragmented regulations across regions complicate the deployment of standardized heat capture systems, as discussed in industry reports.

4. Scalability and Applicability

  • Geographic Constraints: Geothermal energy is viable only in geologically active areas, limiting its global applicability, as outlined in a waste heat quantification study. Similarly, WHR is most feasible for energy-intensive industries like cement or steel.
  • Seasonal Demand: Heating needs vary seasonally, reducing year-round viability without advanced storage, as noted in thermal storage research.

5. Technological Maturity and Awareness

  • Emerging Technologies: Technologies like advanced thermal storage or low-temperature ORC systems are still developing. A 2025 study emphasizes the need for novel materials with enhanced thermal conductivity to improve system efficiency.
  • Knowledge Gaps: A 2022 bibliometric analysis found that WHR research is concentrated in countries like China, with limited global dissemination.
  • Public Awareness: Heat capture technologies are less visible than solar or wind, reducing public and political support, as highlighted in energy policy discussions.

Critical Evaluation of Waste Heat’s Role in Global Warming

A 2020 study in Environmental Systems Research argues that waste heat contributes to global warming, estimating its radiative forcing at 0.028 W/m² compared to 2.9 W/m² for greenhouse gases. However, this claim is debated, as it may overstate waste heat’s direct climatic impact by neglecting atmospheric absorption. Most sources, including the IEA, emphasize that waste heat’s primary environmental harm comes from the fossil fuels used to generate it, not the heat itself. Capturing waste heat mitigates this by reducing primary energy demand, aligning with sustainability goals.

Evidence-Based Solutions

Every problem comes with potential solutions. Recent studies and industry insights point to clear strategies for overcoming the challenges outlined earlier. Let’s take a closer look:

  1. Technological Innovation:
  2. Policy Support:
    • Implement subsidies, tax credits, and carbon pricing to make heat capture economically competitive. The EU’s promotion of district heating systems is a model for this.
    • Streamline permitting for geothermal projects to reduce delays.
  3. Public-Private Collaboration:
    • Foster partnerships to share costs and expertise. The DOE’s ARPA-E has funded innovative WHR projects, like RedWave Energy’s low-temperature heat capture technology.
    • Engage communities to build support for projects like district heating, as seen in Denmark.
  4. Education and Awareness:
    • Train engineers and policymakers on heat capture benefits, leveraging insights from successful case studies.
    • Raise public awareness through campaigns highlighting projects like Aalborg’s crematorium, which uses waste heat to warm homes.
  5. Life Cycle Assessments (LCAs):
    • Conduct LCAs to evaluate the full environmental impact of heat capture systems, addressing trade-offs like energy-intensive manufacturing processes, as recommended in sustainability analyses.

Natural and Waste Heat is a Sustainable Practice with Robust, Verified Potential

Capturing natural and waste heat is a sustainable practice with robust, verified potential to transform the energy landscape. It offers energy efficiency gains (e.g., 80-90% for CHP systems), emission reductions (e.g., 7 gigatons of carbon-equivalent by 2050 from geothermal heat pumps), and economic savings (e.g., €140 billion annually from WHR). Real-world examples, from Iceland’s geothermal systems to Copenhagen’s district heating, underscore its feasibility. However, technical complexities, high costs, and regulatory barriers, as documented in recent studies, require targeted solutions. By investing in innovation, supportive policies, and public engagement, the world can scale heat capture to meet climate and energy goals, turning wasted energy into a cornerstone of a sustainable future.

Full Source List

  1. International Energy Agency (IEA), “Waste Heat Recovery,” 2023.
  2. McKinsey, “Waste not: Unlocking the potential of waste heat recovery,” 2023.
  3. Energy, Sustainability and Society, “Sustainable energy recovery from thermal processes: a review,” 2022.
  4. Enerquip, “How Almost Any Industry Can Benefit from Waste Heat Recovery,” 2025.
  5. Thermal Engineering, “How waste heat recovery boosts efficiency,” 2024.
  6. PMC, “Opportunities of waste heat recovery from various sources: Review of technologies and implementation,” 2023.
  7. Sustainability Directory, “Why Is Waste Heat Recovery Considered Sustainable Practice?” 2025.
  8. ScienceDirect, “Quantification of global waste heat and its environmental effects,” 2010.
  9. Stellarix, “Waste Heat Recovery: Enhancing Industrial Efficiency & Sustainability,” 2025.
  10. PMC, “Waste heat recovery research – a systematic bibliometric analysis (1991 to 2020),” 2022.
  11. Environmental Systems Research, “Waste heat: the dominating root cause of current global warming,” 2020.
  12. ORNL, “Study: Geothermal Heat Pumps Could Prevent Nearly $600 Billion in Building Energy Costs, Avoid Nearly 7 Gigatons of Carbon-Equivalent Emissions by 2050,” 2024.
  13. MDPI, “Applications and New Technologies Pertaining to Waste Heat Recovery: A Vision Article,” 2025.
  14. DBDH, “Waste Heat – the Overlooked Resource,” 2024.
  15. Sustainable Manufacturing Expo, “Insight 1: Common Methods of Waste Heat Recovery,” 2024.
  16. European Environment Agency (EEA), “Decarbonising heating and cooling — a climate imperative,” 2023.

FAQ: Capturing and Using Natural and Waste Heat for Sustainability

1. What is natural and waste heat capture, and why is it sustainable?

Natural heat capture involves harnessing geothermal energy or solar thermal energy from the Earth or sun, while waste heat capture reuses thermal energy produced as a byproduct of industrial processes or power generation. It’s sustainable because it reduces energy waste, lowers greenhouse gas emissions, and enhances efficiency. For example, combined heat and power (CHP) systems achieve 80-90% efficiency, compared to 30-50% for conventional power plants.

2. How does waste heat recovery work in industries?

Waste heat recovery (WHR) captures excess heat from industrial processes (e.g., cement or steel production) using technologies like heat exchangers or organic Rankine cycle (ORC) systems. This heat can be reused for heating, electricity generation, or other processes. A 2023 study showed a slab-type heating furnace with regenerative burners achieved 72% thermal efficiency, saving 15% fuel.

3. What are the benefits of capturing natural and waste heat?

Capturing natural and waste heat offers multiple benefits:

4. What industries can benefit from waste heat recovery?

Energy-intensive industries like cement, steel, glass, and chemical manufacturing benefit most from WHR. For example, GEA’s XECO® systems recover heat from cement kiln flue gases, enhancing efficiency. Data centers, like Facebook’s facility in Odense, also use waste heat for district heating.

5. What are the challenges of capturing natural and waste heat?

Key challenges include:

6. How does geothermal energy contribute to sustainable heating?

Geothermal energy uses the Earth’s internal heat for electricity or direct heating, producing near-zero emissions. Iceland powers 90% of its heating with geothermal, and a 2024 NREL/ORNL study projects geothermal heat pumps could save $600 billion in U.S. energy costs by 2050.

7. Can waste heat recovery reduce global warming?

Yes, WHR reduces global warming by lowering fossil fuel use. The IEA estimates WHR could avoid hundreds of millions of tons of CO2 emissions annually. However, a debated 2020 study claims waste heat’s radiative forcing (0.028 W/m²) contributes to warming, though its impact is minimal compared to greenhouse gases (2.9 W/m²). Capturing waste heat mitigates this by reducing primary energy demand.

8. What technologies are used for waste heat recovery?

Common WHR technologies include:

  • Heat Exchangers: Transfer heat for reuse in processes.
  • Organic Rankine Cycle (ORC): Converts low-grade heat to electricity.
  • Thermal Storage: Stores heat for later use, per research.
  • Regenerative Burners: Improve furnace efficiency, saving 15% fuel.

9. How can businesses implement natural and waste heat capture systems?

Businesses can start by:

10. Where are natural and waste heat capture systems most effective?

Geothermal systems are most effective in geologically active areas (e.g., Iceland). WHR thrives in energy-intensive industries (e.g., cement, steel) and urban areas with district heating, like Copenhagen, where 98% of buildings use waste heat.

11. What are the costs of installing waste heat recovery systems?

Costs vary by system and industry. ORC systems can cost millions, while simpler heat exchangers are less expensive. Geothermal drilling also involves high upfront costs. However, savings like €140 billion annually and policy incentives can offset expenses.

12. How does district heating use waste heat for sustainability?

District heating systems capture waste heat from power plants, incinerators, or data centers to heat buildings. Copenhagen’s network, using waste heat, supplies 98% of the city, reducing emissions and targeting carbon neutrality by 2025.

13. Are there government incentives for heat capture systems?

Many regions offer subsidies or tax credits for WHR and geothermal systems, though availability varies. The EU promotes district heating, and the U.S. DOE’s ARPA-E funds WHR innovation.

I have a background in environmental science and journalism. For WINSS I write articles on climate change, circular economy, and green innovations. When I am not writing, I enjoy hiking in the Black Forest and experimenting with plant-based recipes.