AHC/WI: Offshore Thermal Power Stations

The earliest proposals for building offshore thermal power stations emerged in the 1950s and 1960s and called for using barges or ships equipped with nuclear reactors to power ocean and river communities. There were some experiments with that under the United States Army's Nuclear Power Program, but they involved small nuclear reactors.

It wasn't until the Offshore Power Systems concept was developed in the 1970s by Westinghouse and Newport News Shipbuilding that there was commercial interest in building large scale power stations offshore.

Although the Offshore Power Systems concept (as with most other offshore thermal power concepts) was developed to mitigate problems with land scarcity and public opposition to nuclear power on the East Coast of the United States, the general concept could have been applicable for other forms of offshore thermal power generation, such as that by coal, petroleum, and natural gas. Nuclear power was a major concern in the 1970s, but so was air pollution, and prior to the development of advanced smokestacks and emission filters (especially flue gas desulfurization) the pollution from conventional power plants tended to be heavy and localized. Going offshore might even be an alternative to using emission control technology, at least in terms of air pollution (especially off the East Coast of the United States, where the prevailing wind is out to the Atlantic Ocean).

In terms of locations, the continental shelf would be ideal for fixed infrastructure. It tends to be no deeper than 200 meters (490 feet) and typically extends 80 kilometers (50 miles) offshore. It would also be possible to simply use power barges or ships. Power could be transmitted to land by an undersea cable. Because transmission infrastructure would already be in place, marine energy (tidal power, wave power, and ocean thermal energy conversion) and offshore wind power could benefit from improved access to the grid.

Could going offshore have been a feasible response to the requirements for extensive pollution controls and environmental/safety studies for new conventional and nuclear power stations? If thermal power stations were built offshore, could it help the development of other marine power systems such as tidal, wave, and wind systems?

 

One barrel of petroleum has 5,729,000 Btu of energy, compared to 19,882,000 Btu for a short ton of coal source, so 3.74 barrels of petroleum would be required to get the same amount of energy as a short ton of coal. Petroleum cost $3.18 per barrel in 1970 (source) while coal cost an average of $6.34 per short ton in 1970 (source), which means that in 1970 it would have cost $11.89 to get as much energy with petroleum as one short ton of coal could provide. However, anthracite coal (which is very low sulfur) cost $11.03 per ton in 1970 (source), which is close to data suggesting it would have cost $0.38 per million Btu to get energy from coal and $0.42 per million Btu to get energy from residential fuel oil in 1970 (source).

Petroleum would thus be slightly more expensive than coal, but the situation is complicated somewhat when the costs of transportation and low sulfur coal are considered (more on that here).