Hybrid geothermal power plants are unique in their utilization of geothermal energy and are an indispensable part of Icelandic energy production. They produce both hot water and electricity, which not only guarantees the quality of life for the public but also contributes to the responsible and efficient use of the geothermal resource. Orka náttúrunnar owns and operates two such plants, Hellisheiði Power Plant and Nesjavallavirkjun.

In a new article published on Vísir today, Hildur Æsa Oddsdóttir, an expert in energy management at ON, discusses the importance of these plants for the energy security of the country, which encompasses many aspects of society. She points out that the energy security strategy for the future must consider various energy sources to ensure the continued responsible and efficient use of our resources - both for current generations and those to come.

The article can be read in full below.

Geothermal energy for the benefit of society: The energy that keeps Iceland warm

Hybrid geothermal power plants are unique in their utilization of geothermal energy. They are special because they produce both hot water and electricity, which not only guarantees the quality of life for the public but also utilizes the geothermal resource in a responsible and efficient manner. Orka náttúrunnar owns and operates two hybrid geothermal power plants, namely Hellisheiði Power Plant and Nesjavallavirkjun.

Despite the unique properties of hybrid geothermal power plants, they face challenges in meeting the fluctuating demand of the public, as can be seen in the accompanying image.

The output of geothermal power plants is generally quite stable; they produce nearly the same amount every hour of every day and month. At the same time, the public's demand for electricity varies at different times of the day and also differs between weekends and weekdays, leading to fluctuating usage from one hour to the next. It is this variable usage that geothermal power plants struggle to accommodate.

Constant output, similar to that of most geothermal power plants, is poorly suited to meet the fluctuating demand of the public. This is evident in the image, where it can be seen that production is either significantly above or significantly below usage. To meet the needs of the public, it is necessary to have the capacity to adjust output. In Iceland, flexible power comes from hydropower plants, almost exclusively from Landsvirkjun's plants.

The advantage of hybrid geothermal power plants is that the same geothermal fluid, which is a mixture of steam and hot water, can be used to produce both hot water for heating and electricity. Thus, when the weather is very cold, it is possible to increase the production of hot water to ensure a supply of hot water. However, the downside is that this increase leads to reduced electricity production. By having this flexibility, we can meet varying societal needs for heating, which Orka náttúrunnar sees as its social obligation while also fulfilling legal obligations that prioritize the production of hot water in such plants over electricity production.

The electricity consumption of the public and electricity production in hybrid geothermal power plants are often interlinked, but in opposite directions. This connection can arise from the demand for hot water and increased hot water production, which can come at the expense of electricity production. Electricity consumption and hot water usage often increase simultaneously, for example, when the weather is very cold. In severe cold, electricity consumption rises, for example, due to electric heating and increased electricity use in hot water pumps to respond to the increased hot water demands. Additionally, people tend to stay home more on cold days, thus consuming more electricity. Consequently, both electricity and hot water usage increase, but electricity production decreases because the production of hot water takes precedence to meet the increased demand. Therefore, hot water production increases at the expense of electricity production on cold days when electricity and hot water usage rise simultaneously.

In recent years, Orka náttúrunnar has ensured that the electricity consumption of the general market is well above its production rate of electricity. Despite generating only about 17% of the electricity in Iceland, a significant share, between 25-30% of the electricity consumed by the public has come from Orka náttúrunnar's plants in recent years. In comparison, it should be noted that Landsvirkjun, which produces 73% of the electricity in Iceland, currently only meets approximately 50% of the public's electricity needs, but if one is to interpret the company's discourse, that share has been much lower in recent years.

Solutions to ensure the energy security of the public must be considered in a comprehensive context. Historical sales in the electricity market do not necessarily reflect future sales potential. Additionally, one cannot focus solely on electricity security; hot water security, or thermal security, is equally important for the nation's energy security. Any potential obligations imposed on electricity producers to ensure electricity for the public must therefore always be evaluated in the context of other obligations made to energy companies, especially those that operate hybrid geothermal power plants. It would be unacceptable to impose additional obligations on energy companies that conflict with other obligations in electricity laws.

Hybrid geothermal power plants are an indispensable part of Icelandic energy production. By producing both electricity and hot water, they contribute to energy security encompassing many aspects of society. To meet future challenges, the energy security strategy must consider various energy sources - which is a prerequisite for us to continue utilizing our resources responsibly and efficiently for the benefit of both current and future generations.