Ilmenauer Wärmeversorgung

Ilmenauer Wärmeversorgung GmbH (IWV) is the municipal district heating and cooling utility for Ilmenau, a university town in Thuringia, Germany. It is a joint venture owned 51% by the City of Ilmenau and 49% by Iqony Energies GmbH, and was founded on 26 November 1991. The company supplies holistic, resource-conserving heat energy across the core urban area of Ilmenau, operating a district heating network more than 70 km long with annual heat sales exceeding 80,000 MWh. IWV's origins trace back to 1972, when central district heating began supplying major industrial operations such as the 'Werk für Technisches Glas' and 'Henneberg Porzellan' as well as new residential developments. The network later expanded to serve the buildings of the Technical University (now TU Ilmenau). From the outset the system used combined heat and power (CHP), initially fired by heavy fuel oil, then by 14 raw lignite boilers from 1983. After the company's formal establishment in 1991, generation was modernised and the network expanded, using natural gas and heating oil; a gas turbine CHP plant operated from 1995 to 2010. Since 2001 IWV has also offered district cooling and tailored contracting solutions, including cooling for TU Ilmenau and various local heating islands. A major environmental milestone came on 21 July 2005 with the commissioning of the Ilmenau biomass combined heat and power plant, after which more than half of the district heat has been generated from biomass while also producing electricity. In 2013 a biomethane CHP unit and a flue gas heat exchanger were added to further boost efficiency. According to the company's 2025 energy assessment, the district heat has a primary energy factor of 0.22, a fuel-mix emission factor of 0.1543 kg CO2/kWh, a renewable energy share of 77.90%, and a combined heat and power share of 85.84%. IWV is a member of the Thuringia Sustainability Agreement (NAThüringen) and has drawn attention in the regional business press for its climate-neutral, largely CO2-free district heating. The company is currently pursuing a heat network expansion and decarbonisation roadmap in line with Germany's Heat Planning Act (Wärmeplanungsgesetz).

The history of central district heating in Ilmenau began in 1972, when the system started supplying major industrial enterprises — the 'Werk für Technisches Glas' (Technical Glass Works) and 'Henneberg Porzellan' (Henneberg Porcelain) — as well as the emerging new residential areas. Later, buildings of the 'Technische Hochschule' (Technical College, today TU Ilmenau) were also connected to district heating. From the very beginning, the system relied on combined heat and power (CHP), using heavy fuel oil as fuel to generate both district heat and electricity. In 1983, 14 raw lignite boilers replaced the heavy oil plant; these operated into the 1990s. The present-day Ilmenauer Wärmeversorgung GmbH was founded on 26 November 1991 as a joint company of Iqony Energies GmbH (49%) and the City of Ilmenau (51%). Following its establishment, the generation plants were progressively modernised and the district heating network expanded, with natural gas and heating oil becoming the fuels. A gas turbine CHP plant was commissioned in 1995 and operated until 2010. Since 2001, IWV has also offered district cooling and tailored contracting solutions, such as the cooling supply for TU Ilmenau and various local heating islands. A decisive environmental turning point came with the commissioning of the Ilmenau biomass combined heat and power plant (Biomasse-Heizkraftwerk Ilmenau) on 21 July 2005. Since then, more than half of the district heat has been generated from biomass, while electricity is produced simultaneously. In 2013, a biomethane CHP unit and a flue gas heat exchanger were put into operation to further increase efficiency. Today IWV operates a network more than 70 km long with annual heat sales exceeding 80,000 MWh, serving the entire core urban area of Ilmenau. Its 2025 energy assessment reports a primary energy factor of 0.22, a fuel-mix emission factor of 0.1543 kg CO2/kWh, a renewable energy share of 77.90%, and a CHP share of 85.84%. The company is a member of the Thuringia Sustainability Agreement (NAThüringen) and is pursuing a heat network expansion and decarbonisation roadmap under Germany's Heat Planning Act.

• 2013

  Biomethane CHP unit and flue gas heat exchanger put into operation to further increase efficiency.

• 2005

  Ilmenau biomass combined heat and power plant commissioned on 21 July; more than half of district heat generated from biomass.

• 2001

  IWV begins offering district cooling and tailored contracting solutions.

• 1995

  Gas turbine CHP plant commissioned, operated until 2010.

• 1991

  Ilmenauer Wärmeversorgung GmbH founded on 26 November as a joint company of Iqony Energies GmbH (49%) and the City of Ilmenau (51%).

• 1983

  14 raw lignite boilers replace the heavy oil plant.

• 1972

  Central district heating begins in Ilmenau, supplying major industrial enterprises and new residential areas.

Municipal, sustainability-oriented heat and cooling utility emphasising resource conservation, combined heat and power, and decarbonisation.

• District heating (Fernwärme)

  Heat supplied through a network more than 70 km long, with annual sales exceeding 80,000 MWh.

• District cooling (Fernkälte)

  Cooling supply offered since 2001, including for TU Ilmenau.

• Contracting solutions

  Tailored contracting solutions such as local heating islands.

• Electricity from combined heat and power

  Electricity produced alongside heat, notably at the biomass CHP plant.

1. 1IWV - Ilmenauer Wärmeversorgung – Homeiwv-ilmenau.de
2. 2IWV - Ilmenauer Wärmeversorgung – Über Unsiwv-ilmenau.de
3. 3Ilmenauer Wärmeversorgungwikidata.org