The water was hot-tub tepid and stank of sulfur. Dipping my hand
in the mineral-laced liquid spilling out of a PVC pipe wedged into
the ground, I felt the wet heat tingle my fingers. Here at the
Gilroy Hot Springs, a state historic landmark located on the
southern end of Henry W. Coe State Park, folks got into hot water
for more than 140 years. I have a hunch that during all those
years, few visitors realized the energy heating their H2O bath came
from a nuclear-powered furnace far beneath their feet.
The water was hot-tub tepid and stank of sulfur. Dipping my hand in the mineral-laced liquid spilling out of a PVC pipe wedged into the ground, I felt the wet heat tingle my fingers. Here at the Gilroy Hot Springs, a state historic landmark located on the southern end of Henry W. Coe State Park, folks got into hot water for more than 140 years. I have a hunch that during all those years, few visitors realized the energy heating their H2O bath came from a nuclear-powered furnace far beneath their feet.
The Gilroy Hot Springs is now a derelict site, dotted with crumbling cabins, a decaying bathhouse, and a few other neglected buildings. Touring it, you get a sense that in its glory days, starting in the 1880s and lasting through the 1920s, the Gilroy Hot Springs was one of California’s most luxurious vacation resorts. Think of it as a kind of Club Med of the Victorian era, drawing the rich and powerful from San Francisco. Up to 500 guests often stayed the summer, escaping from the Frisco fog to soak in tubs and swimming pools warmed by the hot springs, spending their time enjoying fine cuisine, dancing to waltzes, taking nature rambles and gambling into the moonlight hours.
The energy that made these visitors’ hot spring resort experience possible originated from the myriad massive stars that once filled the void of the universe nearly 10 billion years ago. When occasionally one of these immense stars exploded in an astronomical event known as a supernova, it spewed into space the debris of its destruction. The heavier elements – including the minerals that make up our bodies – all were forged in these star furnaces.
About 4.5 billion years ago, some of the celestial clouds of supernova stardust collected to shape the spheres of our solar system’s planets. Iron sank to form Earth’s core, creating a metal orb 1,500 miles across as the heart of our world. Above this was a sea of molten mantle containing billions of tons of uranium, thorium and potassium – elements that give off radioactive particles as they decay over vast geological timescales. Thus, Earth’s inside is “cooked” by nuclear power, which sustains its temperature at about 2,200 degrees.
Earth’s crust is a relatively thin layer of rock and soil floating on top of this mammoth ocean of lava. If you could see from space a multi-million-years-long movie of the Earth sped up to show centuries passing in seconds, you would witness the continents drift across our world’s surface, occasionally ramming into each other and causing mountains to rise in the collision, all powered by the magma heat engine below us.
Consider the colossal quantity of energy – the equivalent of 6.7 trillion tons of dynamite – that generated the earthquake and tsunami that devastated Japan this year. That energy is about 1 percent of the total amount of energy in a single year that reaches Earth’s surface from our planet’s geological depths. If our civilization might someday tap safely and economically into our planet’s geothermal energy, we could power our world for billions of years. We are only now just starting to develop the literally ground-breaking technology to exploit this resource.
There are certain areas of our planet’s crust where the magma is close enough to the surface to heat the ground water – places much like the South Valley’s own Gilroy Hot Springs. Companies have installed geothermal power plants in some of these locations that use the hot water to generate electricity. Researchers are also working on ways to drill holes three or four miles deep into the crust, where the temperature can reach as hot as 400 degrees Fahrenheit. They could then pump water down these holes to retrieve the geothermal energy when it comes back up as steam. There is a danger, though. This deep-rock drilling might unintentionally trigger earthquakes.
Unlike solar and wind power which are generated only during daylight hours or from meteorological conditions, geothermal heat as a well-managed renewable fuel can provide us with a virtually continuous supply of energy. Earth’s mantle is always hot, always roasted by radioactive decay. And although geothermal energy does have some impact on our natural environment, its effect is miniscule compared to the pollution problems that come from our industrial civilization’s vast consumption of the energy stored in the fossil fuels sources of petroleum, natural gas and coal.
Gilroy Hot Springs guests who luxuriated in the resort’s waters more than a century ago probably never dreamed the source of energy heating their baths came from decaying radioactive elements created in the deaths throes of ancient stars. With technological advances, that geothermal energy might soon benefit humanity far beyond heating spring water for a hot-tub soak. It might one day sustain our civilization.
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If you’re interested in visiting the Gilroy Hot Springs for a tour or even a moonlight camping trip where you can enjoy a soak in the hot mineral waters, email: [email protected] or check out the website www.friendsofgilroyhotsprings.org for more info.
