Ocean Thermal Energy Conversion - a hundred year old technology powering today's fight against climate change

In the early 1980s, because of an oil embargo, the US Federal Government enacted the OTEC Act and provided government funding to initiate the implementation of Ocean Thermal Energy Conversion (OTEC) plants for the generation of electricity.

The long-term goal was to install hundreds of OTEC power plants by the year 2000. Unfortunately, by the middle of the 1980’s, government funding was curtailed before an OTEC plant of significant size could be operated. 

However, 98 nations with the adequate ocean thermal resource within their Exclusive Economic Zone (EEZ) were identified. Currently, world-wide numerical ocean-atmospheric models indicate that as much a 50% of the electricity currently consumed throughout the world could be generated with fossil free OTEC technology.

Okinawa OTEC facility

Since the late 1970’s, several relatively small OTEC experimental projects in the USA (Hawai’i), Japan and South Korea have already demonstrated that the technology works 24/7 generating electricity and desalinated water without CO2 emissions into the atmosphere. However, it was also determined that adequately sized pre-commercial projects must be operated in situ and for at least one continuous year to obtain the records required to evaluate what is considered to be commercial sized plant ships that could be deployed world-wide. 

This argument excluded niche markets in small-island-developing states (SIDS) wherein land-based plants sized at a few MW could be cost-effective. Given the current goal for the implementation of renewable energy technologies for the generation of electricity minimizing the use of fossil fuels, OTEC should be considered as a path towards reaching the world-wide 2050 carbon-neutral goals.

Unfortunately, the US government is not currently involved in the implementation of OTEC while South Korea and Japan have taken the lead. There is also some funding for further studies from the European Union and International Agencies. In addition, China is also involved as indicated by numerous journal articles.

It has been speculated that there could be more than 20 trillion dollars spent on OTEC plants over the next 30 years. The new possibilities have encouraged investors in at least Japan and Korea. Currently the only operational plant is a relatively small 100 kW plant on Kumejima Island near Okinawa. It is owned by the Okinawa Prefectural Government with MITSUI OSK Lines, Saga University, and Kumejima Town borrowing it for research and development. Benjamin Martin the Secretary General of the Ocean Thermal Energy Association and as part of Xenesys Inc, operates the plant on behalf of the prefecture.The Korean Research Institute of Ships and Ocean Engineering (KRISOE) has designed a 1 MW plant for Tarawa Atoll in Kiribati. This plant was successfully tested on a barge off South Korea (a site without the thermal resource available off Tarawa) before the Pandemic hit in 2020 and generated 338 kW during trials scheduled to test the equipment. Dr Hyeon-Ju Kim, the principal researcher, is currently planning to install the prototype plant at Tarawa Atoll in Kiribati.

Two other projects are still in the conceptual stage, Yasuyuki Ikegami, Prof., Director of Institute of Ocean Energy,Saga University, in Japan is leading a Mitsui OSK lines proposed Mauritius project and another for Nauru. Whether or not these projects get funded is still in question, but the time may be right. OTEC supporters in the science and business communities believe that with the cost of fuel and concerns about climate change at its present level the OTEC market may be on the cusp of an "avalanche of funding”.

The major conclusion continues to be:  There is a market for OTEC plants that produce electricity and desalinated water, however, operational data must be obtained by building and operating demonstration plant ships scaled down from sizes identified as potentially world-wide cost effective.

The major challenge continues to be: How to finance relatively high capital investments that must be balanced by the expected but yet- to- -be demonstrated low operational costs?

Given that it takes decades for new energy technologies to reach maturity, it seems sensible to once more consider the ocean thermal resource as a renewable energy for the future. 

Perhaps a lesson can be learned from the successful commercialization of Wind Energy due to consistent government funding of pre-commercial projects that led to appropriate and realistic determination of technical requirements and operational costs in Germany, Denmark and Spain. In this context, by commercialization we mean that equipment can be financed under terms that yield cost competitive electricity. This of course depends on specific conditions at each site.

 Please join us for an interesting ZOOM session discussing the 100-year-old technology capable of providing power 24/7 with no carbon dioxide emissions.

The OTEC Program will take place September 2 at 2 pm. Please join us at this HERE