The oceans are a massive resource to address our challenges. Covering seventy percent of our globe, the oceans are by far the largest solar collectors on Earth. Almost all of the sunlight that falls on the oceans is captured as heat in the surface layers.
The deep ocean forms a huge reservoir of cold, nutrient rich water, continuously replenished by the global thermohaline circulation, bringing cold water from the arctic regions in massive amounts. The oceans can thus provide an enormous amount of clean and renewable energy.
Utilizing the cold water directly in cooling systems, energy reductions of up to ninety percent are achievable by a process called SDC, or Seawater District Cooling. The deep ocean resource can also be used to drive a process called OTEC, or Ocean Thermal Energy Conversion, to extract thermal energy from the seas and convert it into electricity.
Because of the stable temperatures of the water in the tropics, with small daily and seasonal changes, SDC and OTEC form so-called baseload sources, requiring no backup to cope with fluctuations, as is the case with for instance solar and wind power. High renewable energy penetration at low cost is therefore feasible.
SDC and OTEC target the first 2 layers of the Trias Energetica, energy conservation and renewable energy generation, contributing optimally to a sustainable, clean future.
OTEC can provide a vast amount of clean and renewable energy at fixed, competitive pricing. Tropical regions with access to the resource can reach 100% independence in a sustainable, economically viable manner, by taking advantage of this baseload resource and complementing other intermittent renewable energy technologies. Promising initial markets for OTEC are tropical islands and coastal regions, where the temperature difference is 20 °C or more (as shown in the fugure below, where red means better resources). These regions, with population centers near the coast, are experiencing rapid growth in energy demand. At the same time, they also have the advantage of having the ideal conditions to deploy OTEC technology to fully meet their energy needs.
The enormous global potential of OTEC is increasingly visible, not least because leading publications such as the IPCC (Intergovernmental Panel on Climate Change) and IIASA Global Energy Assessment reports acknowledge the huge technical and economic potential. According to the latest IPCC report, Ocean Thermal Energy has the largest recoverable potential from all renewable ocean energy technologies. The global potential that can harnessed from the ocean without harming the natural ocean cycles and at competitive costs is estimated to be between 5 and 10 TW, more than two times our current global electricity demand. Additonionally, OTEC has a capacity factor between 80% and 100%, meaning that OTEC electricity production is very reliable and predictable.
The cost of fossil fuels continues to increase in a time where ‘cheap oil’ seems to be over. At the same time, the associated effect of large scale consumption of fossil fuels on climate change comes with large (environmental) costs. Today, global public opinion is increasingly supporting renewable energy technologies like OTEC, and the need to transition to a clean and renewable energy use has never been more apparent. Ocean thermal energy conversion is considered a key technology to make this energy transition happen.