Green Stack: Tidal Energy

There are several good places for The United States to take advantage of the tides for energy.  Passamaguody Bay, which is on the southern end of the Bay of Fundy, has been a target for tidal power development for a long time.  In 1935, Roosevelt tried to develop a project but was shut down by congress.  In 1963, JFK revived the project and made plans for a 550 MW plant but it didn’t go any further after he was assassinated.

In addition to Passamaguody Bay, there are two underwater turbine projects in the Martha’s Vineyard area that are trying to get started; one of which is a 300 MW project.  In addition, experts believe that the Cape Cod area has a lot of other good locations for tide power generators.

There has also been some experimentation with tidal power on New York’s East River.  The first attempt to install a station failed when the strong tides broke some of the key devices, but there is strong potential there.

The Californian company PG&E is also exploring options for extracting tidal power in the San Francisco Bay.  Some observers believe a plant of up to 400 MW is a reasonable size.

If we add up the three plants that we have data for, we get 1250 MW (550 + 300 + 400).

In order to compensate for the lack of data on some of the existing plants, we assume that doubling this number to make 2500 MW is a reasonable estimation of current tidal power extracted.  To roughly estimate how much is possible for us to attain, we multiply this number by 10. This multiple includes adding more plants and increasing the efficiency of the existing technology.  This gives us an expected 25000 MW in the near future.

After some unit conversion, we get roughly 1.9 kWh/day/person.  The math is shown below.

25000 MW = 25000000 kW

25000000 kW * 24 hr = 600,000,000 kWh

600,000,000 kWh / 312,000,000 people in the US = 1.9 kWh/day/person

In addition to the above tidal energy, the biggest source in the United States is the Gulf Stream that runs by Florida.  Experts estimate that at peak performance the Gulf Stream could generate 11.16 kWh/day/person.  If we add these two numbers together, we get a total of 13.1 kWh/day/person from tidal energy.

Figure 1. Model of underwater turbine used to collect tidal energy