The Phare des Baleines Lighthouse on Île de Ré: A Testament to Energy Transitions
Every summer, the population of Île de Ré—which numbers just over 17,000 in the winter—increases tenfold. Vacationers flock to the beaches along the coast and to the approximately 110 km of bike paths.
Christian de Perthuis, Paris Dauphine University – PSL and Boris Solier, University of Montpellier
One of the must-do activities during your vacation is a visit to the Phare des Baleines. Located at the northwestern tip of the island, the lighthouse was named after the whales that used to wash up on the beach below.
Standing 57 meters tall, this structure offers a unique panoramic view to the intrepid visitors who climb the 257 steps leading to the top. Its history is also a story of the many innovations that have made it possible to project light ever farther.
The Phare des Baleines thus serves as an excellent indicator of past energy transitions, as analyzed in a recent study by the Climate Economics Chair.
From Whale Oil to Electrification
The story begins during the reign of Louis XIV. The construction of the Tour des Baleines, located between the current lighthouse and the coastline, was commissioned by Colbert, then Secretary of State for the Navy, and completed in 1682 under Vauban’s supervision.
The tower was originally lit with fish and whale oil, which provided poor illumination and was inefficient, as the burning oil tended to char the lantern’s glass panes. Whale oil was the preferred fuel at the time, to the extent that global demand for lighting dangerously accelerated the hunting of this marine mammal, which is now protected.
Ludovic/Flickr, CC BY-SA
As early as 1736, coal replaced whale oil as a fuel. It was burned in a stove topped with a dome designed to reflect the light. This change improved lighting efficiency but required the transport of large quantities of coal. Records from the Cordouan Lighthouse, located at the mouth of the Gironde River, reveal that the lighthouse keepers had to carry up to 100 to 150 kg of coal daily to feed the fire. This is why coal was later replaced by kerosene, before the switch to electricity in the early20th century.
The switch from whale oil to coal made it possible to improve lighting efficiency. For the same mass, coal’s calorific value—that is, the amount of energy produced when it is burned—is in fact much higher than that of whale oil. Similarly, the subsequent replacement of coal with petroleum further increased lighting efficiency.
The shift toward primary energy sources with increasingly high energy density is one of the key characteristics of the energy transitions analyzed by Vaclav Smil. Using a historical approach, the author shows that this increase in energy density has led, on a global scale, to an unprecedented rise in energy consumption andCO2 emissions from fossil fuels.
The Lever of Efficiency Gains
Improvements in the energy sources used by lighthouses were accompanied by innovations in energy conversion and light diffusion techniques, first through the invention of the Fresnel lens by the French engineer Augustin Fresnel (1822), and later through the electric light bulb, credited to Joseph Swann (1878) and Thomas Edison (1879).
The old Baleines Lighthouse, whose range was considered insufficient, was replaced in 1854 by the current lighthouse, which is twice as tall. It was one of the first to be equipped with a Fresnel lens—which is still in use today—enabling it to reach a range of approximately 50 km.
Jean-Christophe Benoist/Wikimedia, CC BY
In 1904, a steam-powered electricity plant replaced the earlier combustion systems. The Phare des Baleines was not connected to the power grid until the 1950s. With the advent of electricity, the lighthouse’s range was once again greatly increased thanks to the efficiency of light bulbs in converting energy into light.
Technical advances in the conversion of energy into light were even more decisive in increasing the range of lighthouses than the increase in the quantity and quality of the primary energy used. This is consistent with the findings of Fouquet and Pearson, which demonstrate the major role that efficiency gains have played in reducing lighting costs over the past two centuries.
A broader lesson for energy transitions: just as much as the mix of energy sources—which is often the focus of debate—the chain of transformation from these sources to end uses is a critical link in energy systems and their transformations.
From Light to Satellites
The etymology of the word “lighthouse” traces back to the Greek word “Pharos,” named after the island where the famous Lighthouse of Alexandria once stood, which disappeared more than 700 years ago. While modern-day lighthouses have not disappeared, most are designated as historic monuments, as their operation, uses, and purpose have changed significantly since they were built.
The advent of electricity initially paved the way for the automation of lighthouses. The last keeper at the Baleines Lighthouse left in the early 2000s, when its operations were fully automated.
Advances in satellite-aided navigation—which is now installed on most boats—have since drastically reduced the usefulness of lighthouses, to the point that some are now up for sale. The Phare des Baleines will certainly continue to sweep the ocean with its beams of light for a long time to come, even though its original purpose—guiding navigation—is now somewhat obsolete.
As visitors make their way down the lighthouse’s 257 steps, they are sure to wonder about the current energy transition. Has the shift from lighthouses to satellites for guiding ships reduced the demand for fossil fuels and, consequently,CO2 emissions?
It’s probably the other way around: the primary energy used by information technology isn’t directly visible, unlike whale oil or the coal hoisted to the tops of old lighthouses. But it is high because satellite imagery involves an entire infrastructure that consumes “gray energy.” Above all, satellite navigation enables a wide range of end uses and contributes to the very rapid growth of maritime shipping—one of the sources of CO₂ emissions.2 which is growing the fastest in the world!
Christian de Perthuis, Professor of Economics and founder of the Chair in Climate Economics, Paris Dauphine University – PSL and Boris Solier, Associate Professor of Economics, Research Associate at the Chair in Climate Economics (Paris-Dauphine), University of Montpellier
The original version of this article was published on The Conversation.