All about technology and forces shaping the energy transition in shipping

‘Climate Positive’ Holiday Greetings!

December 22, 2023

Let’s dive right into the math and geeky details behind the emissions footprint of my AI-assisted ‘holiday greetings’ LinkedIn post!

1. Firstly, the post and its reach:

  • The size of the LinkedIn post, including the text and image is estimated at 142 KB. For ease of calculation, I’ve rounded it up to 150 KB.
  • As it is the festive season, I decided to work with the best case reach scenario:
    my best performing LinkedIn post ever had 43,631 impressions, 292 reactions, 26 comments and 7 reposts. This totals to 43,956 interactions. I’ve rounded this up to 44,000 to account for any reactions to the reposts that I might have missed.
  • For the purpose of this exercise, all reactions have been considered equal; i.e., they consume the same amount of energy and consequently produce the same amount of emissions.
  • ChatGPT roughly estimated that the energy required for loading a 150 KB social media post on a smartphone with average efficiency might be around 0.3-1.1 Wh (considering device energy, network energy, screen energy and idle energy). I’ll work with the average of these two values, 0,7 Wh per impression/interaction.
  • Loading the social media post on a computer with average efficiency would require between 1.25 and 6.3 Wh. I averaged these two values to arrive at 0.57 Wh.
  • Assuming 85% of the interactions are on a smartphone, and 15% on a computer, the weighted average energy consumption per interaction of the 150 KB post is 1.16 Wh.

2. Onto the ‘network’:

  • I have a global network, and I assume that the geographic distribution of where the reactions have come from is a simplistic extrapolation of the location of this network.
  • I asked ChatGPT to estimate the carbon intensity of 1 Wh in different countries and then calculated the weighted average carbon intensity per interaction.
  • Based on these two elements, I calculated the Weighted Average Carbon Intensity of one interaction from my LinkedIn network. This cames up to 0.18 gCO2e/Wh.
GeographyAverage Carbon Intensity per Wh
LinkedIn Network DistributionWeighted Carbon Intensity contribution
Total 100%0,18
Weighted Carbon Intensity of an interaction from my LinkedIn network
Calculated based on data provided by ChatGPT on grid intensity. Data years 2020 or 2022

Based on 1. and 2. above, the emissions from this post would be 1.16 Wh*0.18 gCO2e/Wh*44,000 = 9.13 kg CO2e

3. Thirdly, the energy consumed during the production of this post:

  • The work on this post took about 8 hours.
  • I used a MacBook Air for ~87% of the time, a recent iPhone for ~11% of the time and a Windows laptop (older than the other two devices and less efficient) for about ~2% of the time.
  • After failing to get DALL.E to remove the smokestack and smoke from the original graphic of the cargo ship, and not succeeding in doing it convincingly without installing heavy software programs that were not yet on my MacBook, I had to use Paint 3D on the Windows laptop to hide the smokestack and the smoke. I don’t see smoke in Shipping’s future 😉
  • I assume that the lower energy consumption of the iPhone balances out the higher energy consumption of the Windows laptop, and therefore ignore the difference in energy consumption of these devices.
  • 8 hours of work at 50Wh (energy consumption of a MacBookAir, moderate use) would produce 0.16 kg CO2e (using NL grid intensity from above table, even though I have an all-renewables electricity plan).

Total expected GHG footprint of the production + LinkedIn interactions of post:
9.13 + 0.16 = 9.3 kg of CO2e

This website is hosted by GreenGeeks and powered by renewable energy. But I do not yet have the functionality to estimate the impact of you reading this detailed analysis. To account for this, I decided to compensate for 10x the above-calculated amount.

4. Compensating for the emissions:

  • I purchased 100 kg of CO2 from Climeworks’ Orca project in Iceland, which captures CO2 directly from the air and stores it underground.  
  • This is only one example of the many sci-fi-like mitigation, removal and alternative fuel solutions that needs to be developed with care and deployed responsibly in order for our planet to endure and prosper in the years ahead.

I learnt a lot while writing this, and I hope it gives you some new insights.

Happy holidays!!

Cover image: DALL.E
Cover image compression: Optimizilla
Research: ChatGPT

Disclaimer: This GHG accounting exercise was just a fun way to explore working with AI tools that have been at the top of our minds in 2023. It does not follow prescribed standards for specific industries or guidance frameworks (like the GHG Protocol), but attempts to emulate the accounting logic for the activity at hand.

Shipping’s new technology ecosystem

November 15, 2021

The maritime technology ecosystem is evolving quickly and the shipping industry’s future most likely holds a multitude of alternative fuels and energy technologies. What’s already out there? Who’s building which technology and what does this new ecosystem look like? Here’s an overview.


  • This overview is TRL-agnostic, and lists (on-board hardware) technologies that are at different stages of development – from lab prototypes to commercially ready systems.
  • Several companies manufacture and supply batteries, fuel cells and other technologies mentioned here, but this overview is focused only on companies that are developing them for maritime deployment. It is also definitely not meant to be exhaustive; it includes companies that caught my attention during my research or ones that I have been following for a while.
  • I am aware that combustion engines, both mono- and dual- fuel options are being developed for different alternative fuels. They have been deliberately excluded as I believe electrification is the most advantageous way forward.
  • I intend to update this overview periodically, to include new technologies and companies.

Comparing battery technologies: Nickel-H2 vs. Iron vs. Li-ion

October 14, 2021

As the world clamours to meet greenhouse gas reduction targets to mitigate climate change and electrify different sectors (especially cars), lithium is fast becoming a hot (pun intended) commodity. A recent outlook by Benchmark Mineral Intelligence mentioned that ‘there isn’t enough capacity within the supply pipeline to meet the demand we’re anticipating over the next decade’ and that ‘the deficit of LCE (lithium carbonate equivalent)* is expected to grow to 50,000 tons by 2025.’ Moreover, soaring lithium demand is expected to exhaust the residual lithium reserve on land by 2080.

The largest producers of lithium today are Australia, Chile China, Argentina, US, Brazil, Zimbabwe and Portugal. In 2020, the total annual production of lithium amounted to 82,000 tons. Total identified (land-based) lithium resources stand at 86 Million tons; Bolivia, Chile and Argentina (the ‘lithium triangle’) are home to > 50% of these. Several initiatives are looking into potentially extracting significant amounts of lithium from seawater. Environmental, social and ethical issues have long been bones of contention in lithium production.

Several companies and researchers are working on different battery chemistries that aim to store energy at lower costs than lithium-ion batteries, have lower lifecycle climate impact, and reduce our dependence on lithium. A few such chemistries that have made big waves recently are EnerVenue’s nickel-hydrogen battery, ESS Inc’s iron flow battery and Form Energy’s iron-air battery. The following table compares these on a few basic parameters to the ubiquitous lithium-ion batteries. It is important to note at this point, that there are several lithium ion battery chemistries in use today, including Lithium-Iron Phosphate (LFP), Lithium-Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium-Nickel Manganese Cobalt (NMC), Lithium-Nickel Cobalt Aluminium (NCA), and Lithium-Titanate Oxide (LTO) and they could use different types of anodes, including carbon (graphite, hard carbon, soft carbon, graphene), silicon, and tin.

The cost per kWh is compared below without taking into account the balance of plant (all the components surrounding the battery cells) and the integration specific to each chemistry or application (automotive, marine, etc.). These additional costs can be quite significant, especially in the case of maritime batteries. For marine applications, batteries are required to meet more stringent safety and operational parameters when compared to batteries used in cars or for stationary applications. They also tend to be much larger, as even the auxiliary power systems of inland or short sea cargo vessels would require far more capacity than a Tesla model S for example.

The number of vessels operating with batteries on board has grown rapidly over the last decade. The Maritime Battery Forum’s ship register estimates that there are > 400 vessels with batteries on board, either in operation or on order in 2021.

It might take a while for nickel or iron batteries to be mature enough / ready to be deployed in the maritime space. Some of them may not even be suitable for onboard applications given conditions like salt water, humidity, vibrations due to currents, etc., or their physical footprint. But they are interesting developments to follow, as they could be combined with Li ion batteries to offer more economical, optimised and sustainable solutions to decarbonise port operations or increase access to shore power.

*Lithium carbonate as well as lithium hydroxide are both required for batteries. But other other lithium compounds are typically produced from lithium carbonate, making it the reference point for measuring production.

**Data from: BNEFESS Inc.TechCrunchRecharge NewsRedefining Energy Podcast — Long Duration Energy Storage: The “Final frontier”Form Energy.

Post first published on 3 October 2021, and updated on 14 October 2021.

Could gravity speed up the shift to renewables?

May 21, 2021

I’d like to believe that an apple did hit Newton on the head, and that led him to discovering gravity. The story is just more fun that way. But whether or not the apple actually fell on his head, according to the manuscript in the archives of the Royal Society, an apple definitely seems to have been involved. Newton’s Principia, explaining the phenomenon of gravity was first published in Latin in 1687. And it created quite a ruckus.

Now, over 300 years later, climate change is hitting us on the head in no uncertain terms, and gravity seems to be making a comeback. As we rapidly transition towards producing more and more energy from intermittent renewable sources like wind and solar, we must find efficient and effective ways to store this energy at scale, and reuse it when needed. I’ve been curious about sustainable ways to store energy over long periods of time, so I started looking into what’s out there. This post is focused on exciting gravity-based solutions and the companies working on them.

The underlying ‘gravity’ concept is similar to that of traditional pumped hydropower. To put it very simply, energy is used to pump water up to a height. When the water is released, and it passes through a turbine, it releases this energy. The challenge with pumped hydro, however, is that it requires a suitable location with water and appropriate surrounding topography (hills for reservoirs at different heights for example) for us to be able to harness it.

Novel solutions, using this concept, but replacing water with other materials (like bricks and weights)b, or creating the possibility to tap into hydropower in more widely available locations are being developed.

Why are these gravity-based technologies potential competitors to large, grid-scale battery systems?

  • These installations are modular, flexible and scalable. When the capacity of a single installation is reached, they can easily be installed in multiples — we could very well have gravity-storage parks, just like windfarms.
  • They have lower ‘valuable’ resource intensity. The installations are made from steel, concrete and composites, which are cheaper and more easily accessible than lithium, zinc, and other metals required for batteries. As they do not require complex or advanced materials, decommissioning and recycling at end-of-life are relatively straightforward.
  • They are designed to be in service for 40–50 years, during which they would only see mechanical wear-and-tear. This high asset longevity can contribute significantly to achieving a lower cost per kWh of storage capacity.
  • Existing infrastructure like decommissioned mine-shafts can be used for some of these concepts, making deployment easier. In the case of hydropower, some of these new concepts make it possible to utilise much smaller slopes and even artificial tanks and reservoirs.
  • These systems can be combined with other energy storage options like hydrogen, thermal storage or even batteries.
  • The bricks and weights used have the potential to be carbon ‘sinks’. Using materials like concrete from CarbonCure or Carbicrete, or composites made from recycled industrial waste could help add another dimension to their impact.

Who is building these technologies and what are the systems like?

Here’s a non-exhaustive list –

Energy Vault (Switzerland, founded 2017):
Energy Vault’s solution replaces the water in pumped hydro with custom made 35-ton composite blocks made from low-cost materials. The concept video reminds me of playing Tetris, but with real-life bricks going in two directions — ‘recharging’ when the bricks are taken up and placed on top of the tower and ‘discharging’ when they are brought back down. Energy Vault estimates the round-trip energy efficiency to be between 80–90%. The plants are designed for ranges of 20–35–80 MWh storage capacity and a 4–8MW of continuous power discharge for 8–16 hours. They are also developing solutions to offer full scalability from 1 MWh modules up to multi-GWh of storage capacity. Their first demo site is in Tinicio, Switzerland.

Gravitricity (UK, founded 2011):
Gravitricity’s system suspends weights with the help of cables in a deep shaft. Each cable is engaged with a winch capable of lifting its share of the weight. Electrical power is consumed when raising the weight and generated by lowering it. The system is estimated to have an 80–90% efficiency, can utilize decommissioned mine shafts (> 300m depth) and has a design life of up to 50 years, enabling a low cost of storage per kWh. Their first 250 kW demo in Edinburgh recently generated (shore-)power for the first time, and a full-scale, 4 MW plant is planned to start later this year. Gravitricity recently announced plans to add compressed hydrogen and thermal storage to their installations.
study (in 2019) by Imperial College London estimated that Gravitricity’s technology could store energy at half the cost of Lithium-ion batteries. Even considering the drop in battery prices over the last year, this is a significant advantage.

Advanced Rail Energy Storage (USA, founded 2010):
Sheldon Cooper (or any ‘trainiac’) would absolutely love this one!
ARES’ fixed motor, chain-drive system uses electricity to drive mass cars uphill on fixed rail tracks, converting electricity into potential energy. When power is required, this process is reversed and the mass cars go downhill; the electric motors operate as generators, converting the potential energy back into electricity. The amount of energy stored depends on the number of mass cars and the (perpendicular) height of the slope. Storage capacity can be increased by adding more tracks, and duration by increasing track length. Each mass car is 25% longer and about twice as wide as a standard twenty-foot container (TEU) and weighs approx. 320 tons. A 50 MW GravityLine with 10 multi-rail tracks and 210 mass cars is being built in Nevada.

Gravity Power (USA):
The GPM (Gravity Power Module) uses a very large piston suspended in a deep, water-filled shaft, with sliding seals to prevent leakage around the piston and a return pipe connecting to a pump-turbine at ground level. The piston is made up of reinforced rock (or low-cost concrete). The dropping piston forces water down the storage shaft, up the return pipe and through the turbine, producing electricity. To store energy, electricity drives the generator in reverse, spinning the pump to force water down the return pipe and into the shaft, lifting the piston. Each shaft can be used to store several MWh of energy. Water needs to be filled into the shaft once at the start of operations; it can then be reused.

New Energy Let’s Go (Germany):
Their concept, originally developed by Heindl Energy GmbH, involves creating a cylindrical well (in bedrock) in which a large rock mass is pushed up and down with the help of hydraulic pumps. Excess renewable electricity can be used to push water under a movable rock piston, and when electricity is needed, the rock mass is lowered, pushing the water under it through a turbine to generate power. Estimated diameter of a 1 GWh plant is 150m and that of an 8 GWh plant is 250m. New Energy Let’s Go is an interim investor who has acquired the patents and is seeking a strategic investor to continue development.

RheEnergise (UK, founded 2019):
The company is developing ‘HD Hydro’ or high-density hydropower technology that makes it possible to reach the same power output on hills that are 60% lower than in projects using water. This is achieved by using an environmentally benign high-tech fluid (R-19 TM) with a density 2.5x that of water that has been engineered to be non-reactive and non-corrosive. This unlocks several new potential sites, reduces plant construction costs and has the potential to significantly speed up deployment.

Easy Hydro (UK, founded 2019):
Easy Hydro, a spin-out of Trinity College Dublin, makes small-scale (1–200 kW) modular hydropower generating sets suitable for harnessing energy from man-made water networks (e.g. drinking water or irrigation networks) as well as natural ones (rivers, lakes). The installation requires a 10m water column (or 1 bar pressure) and a flow rate of 4 litres/sec. The magnitude of the power output is based on the pressure and flow rates. Easy Hydro uses off-the-shelf water pumps with a reversed flow direction, instead of custom hardware. This enables them to keep costs low, and makes installations easy to repair.

How does the (design) scale of these different solutions compare?

Energy storage solutions can be compared on two aspects. Energy capacity measures the total amount of energy that can be stored in a system (units – kWh, MWh, GWh, etc.) And power capacity measures the maximum amount of power that can be delivered by a system (units – kW, MW, GW, etc.)

For instance, an energy storage installation with an 8 MW, 80 MWh configuration can provide a maximum continuous power of 8 MW for 10 hours, or it can provide a lower, 4 MW power for 20 hours. This design however, cannot provide power higher than 8 MW.

From the examples above, ‘energy towers’ could be made taller or ‘gravity lines’ could be made to go to higher altitudes to increase the energy capacity. The power capacity of the installations could be manipulated by changing the speed at which the bricks / water / mass cars are displaced.

And this is how the energy capacity of individual installations from the above companies (approximately) compares:

In conclusion, for any energy storage solution to be successful, it has to be easily deployable, scalable and low-cost. At sufficient scale, gravitational storage solutions could (theoretically for now) easily compete with batteries on cost, and offer a more environmentally sustainable solution when we compare the entire lifecycle of the technology. This is worth accelerating the work on gravity-based solutions, don’t you think?

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