A Matter of Scale


Recently, I read about an energy storage system in Switzerland that really caught my attention and sent me down a dam research binge. Just before I ventured down this rabbit hole, I got to thinking: “What is big for energy storage?” I remembered back to a couple of years ago when I carried a substantially large (17 inch) workstation laptop with a battery that could not have weighed less than 3 pounds. It felt heavy and bulky. Fortunately, nowadays I have a much lighter computer with more power and way longer battery life. This thought process segued along and I found myself asking this next question: “But what about a car battery system?” The popular Chevy Bolt reportedly has a 960 pound[1] battery pack – that’s certainly more than what Yours Truly can carry. “What if we go bigger?” I then asked myself. In running some quick numbers, the much reported 100 MWh energy storage system installed by Tesla in Australia[2] comes up to at least some 770 tons on just Powerpacks alone, according to their listed weight. This is massive but, as far as infrastructure projects go, not that heavy. “How about BIG?” 9.3×107 metric tonnes of water are stored in the Limmernsee dam in the Swiss Alps. That is a lot of mass to manage that happens to be used for energy storage.

A fact about hydroelectric dams that escapes many (myself included) is that not only are they used as a power source, but the concept of converting the water’s potential energy to electricity also works the other way around, in that it can also work as an energy storage mechanism by using electricity to drive water to a higher potential energy state. One of the weak points of most other readily available renewable energies, such as wind and solar, is their temporary nature and the challenges that come with trying to meet the well-known demand curve, commonly nicknamed the duck curve. Some implementations of large-scale energy storage systems, such as the aforementioned Tesla venture in Australia, have been successful; however, the energy storage issue remains one of the large hurdles for renewable energies. Recently, this hydroelectric power plant was upgraded with variable speed motor generators, which allow it to much more closely match the demands of the power grid, making it a more profitable and reliable operation for energy storage.

Now, so as not to fall behind in conversation regarding dams in wealthy countries, Norway also has some interesting facts that I’d like to share. A country of stark contrasts, as evidenced below in a sample of its dramatic landscapes, is also a place of sharp contrasts in the energy landscape. The people of Norway have made a strong commitment to limit environmentally harmful emissions, and as part of that effort they have implemented steep taxes for fossil fuel powered vehicles. This self-imposed barrier has made Norway into the quickest adopter of electric cars and has made the country hungry for electric cars, which now have a 52 percent market share in new car sales[3]. It appears that as a result of the imposed tax, in 2017, for the first time ever, the sales of gas and diesel started to decline, having been reported as lower than in previous years.

It is important to note, however, that the environmental benefits of electric vehicles can be minimal unless the source of that power is derived from a power plant that doesn’t pollute.  Norway also has that covered. Until Thorium nuclear power plants are developed in Norway, as the plot of the show Occupied – which I highly recommend watching – promises, the country relies heavily in hydropower for their energy production. In fact, it accounts to upwards of 98 percent of the energy production of the country. But, for this Scandinavian country it’s not a new technology – they’ve had hydropower since the late 19th century. This wealth of experience on the subject has given Norway a competitive advantage to provide energy storage as a service, and now has secured contracts with other European countries to store energy on their high mountain lakes with these systems[4]. Norway will be providing the cheapest available storage for Germany’s infrastructure, which in turn is making a bet on solar energy.

As an engineer, I find these large scale systems fascinating. It is exciting to see much of the same engineering principles and thought processes go into solutions from the scale of a Swiss watch, to a Swiss energy storage dam system. Seeing these extreme examples always makes me look forward to new challenges and deepen my appreciation for all the detail that goes into engineering a good product.

-Dan Gutierrez, Mechanical Design Engineer


[1] “The Chevy Bolt — A Deeper Look | CleanTechnica.” 14 Feb. 2016, https://cleantechnica.com/2016/02/14/the-chevy-bolt-a-deeper-look/. Accessed 1 Jun. 2018.

[2] “Tesla builds world’s largest battery in Australian outback.” 1 Dec. 2017, http://www.latimes.com/business/technology/la-fi-tn-tesla-australia-20171201-story.html. Accessed 1 Jun. 2018.

[3] “Electric cars reach new 52% market share record in Norway … – Electrek.” 3 Jan. 2018, https://electrek.co/2018/01/03/electric-car-market-share-norway-tesla-record-deliveries/. Accessed 3 Jun. 2018.

[4] “Norway is Europe’s cheapest “battery” | ScienceNordic.” 22 Dec. 2014, http://sciencenordic.com/norway-europe%25E2%2580%2599s-cheapest-%25E2%2580%259Cbattery%25E2%2580%259D. Accessed 3 Jun. 2018.

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