Written by: Nicole Kastanias
Edited by: Ada Collins
Dating all the way back to the 1880s, Ocean Thermal Energy Conversion (OTEC) was first proposed by French Physicist Jacques Arsene d’Arsonval who drew inspiration from the classic science fiction adventure novel Twenty Thousand Leagues Under the Sea by Jules Verne. (Lawrence and Rafferty 2023) One of the novel’s characters, “Captain Nemo,” suggests the notion of obtaining electricity through the temperature disparities of different depths of the ocean, and in essence, OTEC does precisely that.
The unique benefits of OTEC as a renewable energy source are enticing at first glance; as an ocean-based energy generator, implementation of OTEC technology entirely avoids the issue of infrastructural disruptions on land and takes advantage of the abundance of oceanic surface area. It is a stable, net zero-emissions energy source that can be scalable and versatile within a variety of tropical environments. It is unaffected by daylight and therefore operates 24/7 as a baseload energy source (Hyatt 2017) Despite its promising profile, OTEC has yet to be scaled to any significant level (IEA, 2014).
At the time of its emergence, Nikola Tesla believed the concept to be a promising approach to renewable energy and worked alongside d’Arsonval’s student Georges Claude to in the development of the first OTEC plant in Cuba in 1930. In 1931, Tesla outlined the model in his “Our Future Motive Power,” proposing optimizations to Claude’s project but ultimately both Tesla and Claude came to similar conclusions that the necessary economies of scale for OTEC development would not be practical or attainable at the time (Prasant, 2013).
The discovery of nuclear fission, shortly followed by the discovery of rich oil reserves in the Middle East, in addition to the pessimism on the part of investors towards Claude’s Cuban OTEC project, were the final nails in OTEC’s coffin (US Dep of Energy, 1989).
Since then, OTEC has been trapped in what is known as the “innovation valley of death,” in which large upfront costs must be met by investors to build pre-commercial OTEC plants to demonstrate their potential scale and use, however, such an investment is extremely unattractive without prior assurance that the technology will in fact be successful. The upfront costs of construction for OTEC power plants are significant due to the costs of offshore infrastructure and costs of maintenance of the facility in comparison with the relatively low energy return on investment. This has remained the main obstacle to OTEC’s progression outside of the R&D phase of development into commercial use. (Bitcoin Magazine, 2022)
However, the potential for OTEC as a major source of electricity remains an interest to tropical regions in which its benefits are amplified due to a variety of region-specific characteristics such as proximity to water. As well, many island nations face region-specific challenges to traditional energy distribution that can be overcome by using OTEC as an alternative renewable energy source.
The perfect temperature range for OTEC lies approximately at a 25-degree Celsius difference between surface waters and deep sea, which is found in tropical coastal areas such as Hawaii, the Pacific Islands, and parts of Japan (Lawrence, 2023).
Today, particular interest in OTEC is growing in Hawaii, where one of the two operating OTEC plants in the world is located on the island of Kailua-Kona, with the other located in Japan. By 2045, Hawaii has mandated that all of its energy be sourced renewably (HSEO, 2023). Like Texas, the Hawaiian power grid is entirely independent, and each Hawaiian island owns and operates its own power generation.
The most populated Hawaiian Island, Oahu, may present the most ideal circumstances for the launch of OTEC as a major power source. With a large population and little land to spare, alternative renewable energy sources such as solar or nuclear are infeasible. Hawaii faces the highest electricity costs in the United States, and like other island nations, relies mainly on imported fossil fuels to support its energy needs (Renew Rebuild Hawaii, 2022).
So, what could any of this possibly have to do with Bitcoin? Their connection lies in a shared ability to utilize vast abundances of ocean water.
Despite OTEC’s attractiveness within the Hawaiian context, the issue of upfront costs remains extremely daunting. Small and medium-scale test facilities must be built to demonstrate resilience to risks such as impacts of storms and strong ocean currents, and the consistency of baseload energy supply despite such challenges. However, the initial investment into such a facility would virtually incur a total loss, one that Hawaii cannot afford (Renew Rebuild Hawaii, 2022).
The answer to such an issue may lie in the waste products of OTEC; near-infinite supplies of cold water. Nathaniel Harmon, the Co-Founder of OceanBit, made the connection between the abundance of cold water as a waste product of OTEC, with the specific needs of Bitcoin ASIC miners for cooling mechanisms. (Bitcoin Magazine, 2022).
Bitcoin mining requires significant amounts of money, energy, and time to cool their miners through various methods, such costs directly impacting profitability. Considering the abundance of cool water provided by OTEC, Harmon asserts that OTEC may be the most effective method to mine Bitcoin, as it allows ASIC miners to achieve a “power usage effectiveness (PUE) level 1” which translates into a virtually perfect mining efficiency (Bitcoin Magazine 2022).
Harmon suggests a variety of optimizations and reductions of capital expenditure to the current OTEC model such as moving OTEC plants towards equatorial regions with larger temperature differences, and “grazing” plants rather than fixing them to one location, which could decrease the price of OTEC energy from the currently unattractive value of one dollar per KWH to eleven cents per KWH (Harmon 2022).
He proposes such optimizations in addition to selling stranded OTEC energy to Bitcoin would simultaneously optimize its mining operations while bringing down the overall costs of OTEC through efficient allocation. Regions with large-scale OTEC would enjoy a cheap, carbon-neutral energy source with a flexible baseload subsidized by Bitcoin mining profits (Bitcoin Magazine, 2022).
Despite this refreshingly optimistic vision for the future of OTEC, the long-term and large-scale effects of such technology must be studied rigorously. The next step for OTEC development is the construction of medium-scale facilities to develop extensive data on such effects and externalities of OTEC. Harmon and the Oceanbit team plan to build such a plant, but first, they plan to integrate bitcoin mining into the pre-existing OTEC plant on the island of Kailua-Kona to demonstrate the symbiotic potential of OTEC and Bitcoin (Bitcoin Magazine, 2022).
Harmon posits that in addition to overcoming the innovation valley of death for OTEC, an optimized model would introduce a slew of possible co-benefits of OTEC technology at the commercial level of development. The list of possible co-benefits of OTEC is extensive and includes desalination, sustainably extracting nutrients from ocean water for agriculture as well as mining manganese nodules, powering the energy-intensive processes of green hydrogen production, increasing the efficiency of shallow phytoplankton through nutrient recirculation, and the creation of artificial reefs through seawater electrolysis (Harmon, 2022).
Rescuing OTEC from the innovation valley of death will be no minor accomplishment, but Harmon makes it clear that the possibilities for Oceanbit’s vision of a symbiotic OTEC-Bitcoin relationship only begin at this point. If Oceanbit can successfully prove both the efficiency of integrating Bitcoin into OTEC operations, as well as the resilience of OTEC technology in a medium-sized power plant, they could be the first to harness the energy potential of the largest-bodied renewable resource on earth (Bitcoin Magazine 2022).
Bitcoin Magazine (2022, May) How Bitcoin Can Unlock the Energy of the Ocean for 1 Billion People. Retrieved October 10, 2023 from, https://bitcoinmagazine.com/business/bitcoin-unlocks-ocean-energy
Harmon, N Bitcoin, Unleashing an Ocean of. (2022, October 6). What Bitcoin Did. https://www.whatbitcoindid.com/podcast/bitcoin-unleashing-an-ocean-of-energy
Hawai’i State Energy Office (HSEO) (2023) Hawaii Clean Energy Initiative. Retrieved October 7th from https://energy.hawaii.gov/hawaii-clean-energy-initiative/
Hyatt, Colin (2017, September) Ocean Thermal Energy Conversion. Stanford University. Retrieved October 5, 2023, from http://large.stanford.edu/courses/2016/ph240/hyatt2/
International Renewable Energy Agency (2014, June). Technology Brief: Ocean Thermal Energy Conversion. Retrieved October 5, 2023, from https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2014/Ocean_Thermal_Energy_V4_web.pdf?rev=f8b271abc44549f78f68c25ad1380d9e
Prasant, E., Sahu, K., Chinmaya, E., & Nanda, P. (2013) Indian Ocean Thermal Energy. Retrieved November 18, 2023, from https://www.ijert.org/research/indian-oceanthermal-energy-IJERTV2IS100671.pdf
Renew Rebuild Hawaii (2022) Has the time to turn 100 year old dreams of ocean Thermal Energy Conversion (OTEC) into 24/7 electric power? Retreived October 11, 2023 from https://renewrebuildhawaii.com/blog/2022/has-the-time-for-ocean-thermal-energy-conversion-otec-arrived
Solar Energy Research Institute (1980, May) The Ocean Option: Abundant Energy From the Seas. Retrieved October 10, 2023 from, https://www.nrel.gov/docs/legosti/old/334.pdf