Andy Song
The week before March Break, I was fortunate enough to visit Iceland for 6 days on a joint trip between Crescent School and St. Clement's School. One of the major stops on the trip was the Hellisheiði geothermal power plant (a bit hard to pronounce), operated by the Icelandic energy company Orka náttúrunnar (ON Power). The exhibition there explained how the plant operated and why it was absolutely crucial to Reykjavik -- Iceland's capital.
Location
To give a bit of context, Iceland is situated directly on the Mid-Atlantic ridge, the boundary between the Eurasian and North American tectonic plates. This is a divergent boundary, meaning the plates are constantly moving away from each other at a rate of about 2cm per year. Magma rises up from the space between the splitting plates and forms volcanoes (something Iceland is notorious for having a lot of, as can be seen on the graphic on the right).
Concurrently, Iceland is also on a supposed "hotspot" -- an area where magma from deep down in the Earth's mantle continuously rises up to the surface.(another famous example of a hotspot is Hawaii). This means there is a lot of volcanic activity, but also a lot of opportunity for geothermal energy production, as there is plenty of hot water easily accessible underground.
Different Functions
The power plant uses hot water from deep underground to power a few different functions: generating renewable energy with turbines, providing a water supply for the city, and disposing of CO2 in a self-sustainable manner.
Its primary function of generating renewable energy is the one that first comes to mind. The plant drills boreholes 2.5 km into the underground volcanic system, extracting water up to 170 degrees Celsius from high-temperature wells. The plant separates steam from the hot water, which is used to spin high-pressure turbines to generate electricity.
The plant also functions as a water supply for Icelanders. The high-temperature well water is full of minerals, so it is not used as a water supply, but rather to heat up cold water extracted from other wells in a heat exchanger. The heated water is sent to Reykjavik, while the mineral-rich water is injected back into the ground. Furthermore, the plant extracts water from low-temperature wells (around 80 degrees Celsius) and directly sends it to Reykjavik.
The process of drilling and extraction releases volcanic gases like carbon dioxide, so the plant utilizes Carbfix technology to return CO2 to the ground in a self-sustainable manner. Specifically, CO2 is dissolved in water and then brought in contact with basaltic bedrock. The subsequent reaction forms carbonate in the pores and fractures of the basalt, permanently storing the CO2.
In the image below, the white, crusty substance is the carbonate forming on basalt drill cores.
Relevance to Architecture
Apart from learning about how geothermal energy -- a major form of renewable energy -- works, my main takeaway from this experience is the importance of geographical awareness and self-sustainability. The geothermal energy industry in Iceland effectively takes advantage of Iceland's unique tectonic configuration. 99.9% of homes in Reykjavik are heated with geothermal, and 30% of the country's energy is geothermal. The plant also tries to use every single resource possible (e.g. steam, low-temperature well water, leftover mineral-rich hot water) and cleans up the byproducts of its operations in a self-sustainable way. This sustainable mindset is applicable to every aspect of architecture, and it's something that'll hold significant weight in my future endeavors.
Comments