Winters in Norway can be bitterly cold, with average air temperatures below freezing throughout much of the season and the waters of the North Sea dipping as low as 6° C (43° F). Despite these frosty conditions, when the city of Drammen, a community of 60,000 people located on the Drammen Fjord near the capital city of Oslo, needed hot water at 90° C (194° F) for a new district heating system serving local residents and businesses, it turned to the frigid North Sea as a renewable energy source - and Emerson heat pump technology helped make it possible.
Installing heat pumps to extract heat from water or air is increasingly popular in Europe, largely because the heat they deliver far exceeds the energy they consume, greatly reducing the reliance on fossil fuels and the need for additional renewable energy sources. In fact, the European Commission has designated heat pumps a renewable technology for heating and cooling. But Drammen had several additional goals in mind for this project. It wanted the highest coefficient of performance (COP) possible - the ratio of heat extracted compared to energy consumed. It also wanted a technology solution with low annual operating and maintenance costs. And Drammen ideally wanted the system to use a non-ozone depleting refrigerant with zero global warming impact.
When Emerson Climate Technologies and project partner Star Refrigeration got involved, Drammen’s requirements seemed an unachievable task. This is because most industrial heat pumps in Europe use R-134A, a refrigerant with a very high global warming potential (more than 1,400 times that of carbon dioxide.
One of the few refrigerants that could meet all of Drammen’s efficiency and environmental requirements was ammonia, an efficient refrigerant (designated as R-717) most commonly used by the food and beverage industry for process cooling and refrigeration. Ammonia does not contribute to ozone depletion or global warming, but it also had never been used in a high-temperature industrial heat pump application of this design. In fact, not long ago the application was deemed impossible by the International Energy Agency’s (IEA) Heat Pump Centre, which said there were no suitable high-pressure compressors available to make using ammonia a reality for high-temperature industrial heat pumps.