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| Fig. 1: The marginal CO2 emission factor of average GSHP heat in Finland in 2006 to 2011, as well as what the emission factors would have been if the fuel mix had been the same as it was in CHP DH plants. (Image Source: S. Ingall, after Syri and Rinne. [2]) |
Finland may only have a population of 5.5 million, placing it 118th in the global population rankings, but it consistently punches above its weight on the world stage. Named the worlds happiest country for six consecutive years, Finland is also establishing itself as a leader in climate action. The country has set an ambitious goal to achieve carbon neutrality by 2035, making it the fourth most ambitious target globally and the leading commitment in Europe, ahead of Austria and Iceland with 2040 targets. Renewable energy plays a vital role in this transition, contributing to greenhouse gas reduction, energy security, and economic growth, but central to Finland's approach are its Combined Heat and Power (CHP) systems and district heating networks, which collectively supply over 50% of the nation's heating demands. [1] These technologies maximize energy efficiency, reduce greenhouse gas emissions, and integrate renewable and waste energy sources into Finland's energy mix. [1,2]
Combined Heat and Power (CHP) systems are at the forefront of energy innovation, efficiently generating electricity while capturing and repurposing waste heat for residential, industrial, and commercial applications. In Conventional systems, 100 units of fuel produce 40 units of electricity and the remaining 60 units are discarded as waste. CHP systems extract far more value. From the same 100 units of fuel, CHP systems generate 30 units of electricity and 60 units of usable heat. This results in an overall energy efficiency of up to 90%, compared to the 40 to 50% efficiency of conventional power plants. [2]
In a typical CHP system, fuels such as natural gas, biomass, or municipal waste are combusted to drive a turbine or engine, generating electricity. Simultaneously, the heat produced during this process is captured and redirected for use in district heating networks, industrial processes, or building systems. The integration of CHP with Finland's district heating networks has been pivotal. These systems supply over 50% of the nation's heating needs, showcasing the scalability and adaptability of CHP technology. [1,3]
CHP systems are also economically advantageous, especially when coupled with renewable energy sources. For instance, the municipality of Sodankyl, Finland, recently reorganized its district heating production by constructing wood-fueled CHP plants. This shift not only reduced greenhouse gas emissions but also demonstrated the profitability of such systems when subsidies are applied to offset higher initial investment costs. [4]
District heating is a cornerstone of Finland's urban energy infrastructure, effectively distributing heat from central facilities to multiple buildings via insulated pipelines. These systems have been seamlessly integrated with CHP plants, creating a synergistic relationship that maximizes energy efficiency.
Finland's district heating networks draw from diverse and sustainable sources, including biomass, industrial waste heat, and geothermal energy. For example, a Finnish pulp and paper mill demonstrated a drastic improvement in energy efficiency by integrating secondary heat sources into the district heating system, reducing both emissions and energy waste. [3] By utilizing such innovative approaches, district heating not only supports CHP systems but also enhances the overall sustainability of Finland's energy network.
Combined Heat and Power (CHP) systems provide significant environmental benefits compared to alternative heating technologies, primarily in reducing greenhouse gas emissions. CHP systems in Finland have an emission factor ranging from 70 to 100 gCO2/kWh. [2] In comparison, heat pumps exhibit a higher average emission factor of 200 gCO2/kWh under current conditions. In 2015, Finland posted a total district heat production of 40.8 TWh. [5] Using the midpoint emission factor of 85 gCO2/kWh, we can estimate the emissions from CHP systems and heat pumps, and then calculate the total CO2 savings achieved by CHP.
| Total EmissionsCHP | = | 0.085 kg/kWh) × 40.8 × 109 kWh | = | 3.47 × 109 kg (CO2) | = | 3.47 × 106 tonnes (CO2) |
| Total EmissionsHP | = | 0.2 kg/kWh) × (40.8 × 109 kWh) | = | 8.16 × 109 kg (CO2) | = | 8.16 × 106 tonnes (CO2) |
| Co2 Saved | = | Total EmissionsHP - Total EmissionsCHP | = | 4.69 × 109 kg (CO2) | = | 4.69 × 106 tonnes (CO2) |
By utilizing CHP systems instead of heat pumps, Finland's district heating sector achieves annual CO2 savings of approximately 4.38 million metric tons. This estimate is based on the midpoint emission factor of 85 gCO2/kWh for CHP systems, reflecting their efficiency in converting fuel into heat and electricity. These savings highlight the critical role CHP systems play in advancing Finland's carbon neutrality goals. Further, as illustrated in Fig. 1, the realized emission factors of Finnish CHP district heating plants has historically compared favorably with alternative fuel mixes, further emphasizing their role in achieving emissions reductions.
As Finland progresses toward its 2035 carbon neutrality goal, the role of CHP and district heating is expected to expand further. Advances in biomass gasification and carbon capture technologies could make CHP even more sustainable. Additionally, the integration of renewable energy sources into district heating networks, such as solar thermal energy and geothermal heat, offers promising avenues for reducing the carbon intensity of heat supply.
Globally, Finland's model holds valuable lessons. Cities in cold climates, particularly those in Europe and North America, can replicate Finland's success by adopting CHP systems and developing district heating networks tailored to their energy profiles. However, challenges remain, including the need to fully decarbonize CHP systems and integrate intermittent renewable energy sources into the heating grid.
Finland's leadership in sustainable energy highlights the transformative potential of CHP systems and district heating. By achieving unparalleled levels of energy efficiency and leveraging diverse heat sources, Finland has set a benchmark for nations striving to balance energy security with environmental stewardship. As other countries look to decarbonize their energy systems, Finland's innovative use of CHP and district heating offers a proven pathway to a low-carbon future.
© Scott Ingall. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] S. Proskurina, "Carbon Neutrality in the Finnish Energy Sector: Prospects For a Fossil-Fuel Phase Out," Biofuels Bioprod. Bioref. 18, 1065 (2024).
[2] S. Rinne and S. Syri, "Heat Pumps Versus Combined Heat and Power Production as CO2 Reduction Measures in Finland," Energy 57, 308 (2013).
[3] P. Ruohonen et al., "Analysis of Alternative Secondary Heat Uses to Improve Energy Efficiency - Case: A Finnish Mechanical Pulp and Paper Mill," Resour. Conserv. Recycl. 54, 326 (2010).
[4] H. Haq et al., "An Economic Study of Combined Heat and Power Plants in District Heat Production," Clean. Energy Syst. 1, 100018 (2020.
[5] R. Fischer, E. Elfgren, and A. Toffolo, "Energy Supply Potentials in the Northern Counties of Finland, Norway and Sweden towards Sustainable Nordic Electricity and Heating Sectors: A Review," Energies 11, 751 (2018).