Innovative thermodynamic processes in Waste-to-Energy (WtE)

Why make WtE plants below 200 ktpy?

Small and medium-sized WtE plants meet specific needs:

• Proximity to territory: they reduce the cost and environmental impact of waste transportation.
• Operational flexibility: they are better adapted to variable waste streams and heterogeneous mixes.
• Social acceptability: they are more easily integrated into the urban or industrial fabric.
• Economic sustainability: they require lower initial investment and shorter lead times.

However, to ensure the profitability and efficiency of these plants, it is essential to adopt size-optimized technological solutions. This is where thermal oil boilers and ORC modules come in.

Thermal oil boilers: simplicity and efficiency for compact Waste-to-Energy systems

Thermal oil boilers are a viable alternative to steam boilers, especially in small-scale plants. The main advantages include:

• Low operating pressure: diathermic oil can reach high temperatures (up to 300°C) without the need for high pressures, improving safety and reducing certification and maintenance costs.
• Higher thermal stability: the oil maintains its properties even under varying thermal loads, making the system more flexible.
• Lower energy losses: due to lower evaporation and higher heat transfer efficiency.

These characteristics make thermal oil boilers ideal for powering an ORC cycle, which can take advantage of low to medium temperatures to generate electricity efficiently.

The Organic Rankine Cycle (ORC): efficiency and reliability for Waste-to-Energy plants

The ORC cycle is an established technology for power generation from low and medium temperature thermal sources. Unlike the traditional Rankine cycle, ORC uses organic fluids with lower boiling points than water, allowing power generation even from “weak” thermal sources.

Main advantages of ORC:

• High efficiency at low temperature: ideal for small WtE plants.
• Automatic and continuous operation: reduces operating costs.
• Low maintenance: due to absence of corrosion and mechanical simplicity.
• Modularity: ORC systems can be easily scaled up or integrated into existing plants.

In a WtE system with an oil-fired boiler, ORC is the ideal solution to convert heat to electricity efficiently, reliably, and sustainably.

Technology integration for innovative Waste-to-Energy (WtE) plants: thermal oil boiler + ORC

The integration of oil-fired boiler and ORC cycle is particularly advantageous in decentralized settings, where simplicity and reliability of the system are key requirements. It is also effective in recovering heat from flue gas, since the thermal oil can be heated indirectly, thus avoiding corrosion issues. In addition, in cogeneration configurations, the waste heat generated by the ORC cycle can be used to feed district heating networks or to meet thermal needs of industrial processes.

With this innovative technological combination, electrical efficiencies of up to 30 percent can be achieved, while the integration of thermal recovery or cogeneration can push overall efficiency over 90 percent.

Environmental and regulatory benefits

Small-scale WtE plants with ORC and thermal oil boiler offer numerous environmental advantages:

• Reduced emissions: due to more controlled combustion and more efficient energy recovery.
• Lower visual and acoustic impact: more compact and quieter plants.
• Compliance with European regulations: particularly Directive 2010/75/EU on industrial emissions and the European Green Deal.

In addition, these innovative plants can benefit from incentives for renewable or recovered energy production, improving the return on investment.

Economic and industrial benefits

From an economic point of view, WtE systems with ORC and thermal oil boiler offer:

• Reduced CAPEX: due to simplicity of installation and absence of high-pressure components.
• Low OPEX: because of low maintenance and automation.
• Competitive payback: especially in the presence of incentives or sale of electricity and heat.

In industrial settings, these plants can be integrated into manufacturing districts, port areas or industrial zones, contributing to the decarbonization of processes and the valorization of internal waste.

Future prospects and innovation

The future of small-scale WtE plants is promising, thanks to:

• Digitization and remote control: improving operational efficiency.
• New ORC fluids: with improved thermodynamic and environmental performance.
• Integration with renewable energy: to create hybrid energy hubs.
• Circular economy: with recovery of materials, metals and heat.

In this context, companies such as Turboden are driving innovation, offering tailored ORC solutions for compact, efficient, and sustainable WtE plants.

Conclusions and the role of Turboden

In conclusion, Waste-to-Energy plants under 200,000 tons/year represent a practical, flexible, and sustainable solution to address the challenges of waste management in the contemporary context. At a time when energy decentralization, emission reduction, and circular economy have become priority objectives, these plants offer a technologically mature answer adaptable to different spatial and industrial contexts.

Integration between thermal oil boilers and Organic Rankine Cycles (ORCs) emerges as one of the most effective and innovative solutions to maximize energy valorization of waste in small- to medium-sized plants. This configuration overcomes plant and regulatory limitations associated with the use of high-pressure steam, while offering high electrical efficiency, operational reliability, low maintenance costs, and increased safety.

Environmentally, these plants make a significant contribution to reducing climate-changing emissions, reducing the volume of waste going to landfills, and producing renewable or recovered energy, in line with European directives and climate neutrality goals. In addition, the possibility of integrating waste heat into district heating networks or local industrial processes strengthens the role of these plants as multifunctional energy hubs.

Economically, the modularity and scalability of ORC systems, combined with the simplicity of oil-fired boilers, make these plants particularly competitive even in the absence of economies of scale. The possibility of accessing incentives for energy production from renewable or recovered sources, combined with the growing demand for local and resilient energy solutions, makes the compact WtE model increasingly attractive to public and private investors.

Finally, the growing experience gained by leading companies in the field, such as Turboden, now ensures the availability of turnkey, reliable and customizable solutions capable of meeting the specific needs of each territory or industry sector.

In summary, Waste-to-Energy plants under 200 ktpy with thermal oil boiler and ORCs represent not only an efficient technology, but a model for sustainable development, capable of combining responsible waste management, clean energy production, and enhancement of local resources. In a world that increasingly looks to resilience and circularity, this solution is a candidate for a leading role in the ecological transition in the coming decades.