By CECIL BOTHWELL

In last month’s column I introduced the idea of a Zero Energy District — a geographic area in which residents and businesses aim to produce as much energy as they consume. It’s a lofty goal for modern communities that have grown up relying on fossil fuels. But it is clearly where our energy future lies.

Specifically, I announced the formation of the Asheville Metro Area Zero Energy District (AMAZED), an idea which has been discussed in small group meetings for the past 12 months, and which held its first public meeting May 30.

In order to understand the science underlying a ZED, it’s useful to recall that all of the energy sources on earth derive from the sun (or from pre-existing stars in the case of nuclear power, or the moon in the case of tidal power). Petroleum, natural gas and coal coalesce from the decayed and compressed matter from millions of years of plant growth. So it is really stored solar power. The winds are driven by temperature differentials created in daily and seasonal shifts in the sunlight striking different parts of the planet. Hydropower is available because the sun’s heat lifts water into the sky and drops it on high places whence it runs downhill to drive turbines in dams.

It is actually accurate to say that energy is free. The expensive part is in creating the technology to capture it and put it to work. Over the centuries we have gotten better and better at doing just that. Our earliest civilizations were powered with hay for horses and wood for our stoves. Early America was built with horsepower and timber.

Water power was first effectively harvested with water wheels whose power was used directly to turn millstones and sawmill blades, until the invention of eletrical water turbines installed in dams small and large.

As mining technology and geologic investigation improved, coal replaced wood as the major solid fuel source and today it supplies much of the world’s electric power.

The first widely used liquid fuel was whale oil, harvested from huge creatures that concentrate the sunlight captured by plankton in upper ocean layers. 

Though oil seeps have been used for fuel for centuries, the invention of deep drilling rigs and the discovery of oil in Pennsylvania transformed the liquid fuel economy (and surely saved the great whales from complete extinction). Such drilling released gas as well, and so that became part of our fuel supply.

Wind turbines were initially deployed for water pumping, most famously in Holland, but in the late 20th century they saw rapid refinement into today’s slow-turning, high efficiency electric turbines.

As mentioned above, radioactive minerals formed in the explosion of ancient stars, which coalesced into ore deposits as gas coalesced into our planet, is a significant energy source that isn’t directly attributable to our sun. (Of course, our sun is directly a result of those previous stellar explosions as well.)

All of those energy sources are in some sense “secondary” because they are either previously stored solar/stellar energy, or, in the case of wind and water, derivative from solar heat.

The new kid on the block is direct use of solar power with photovoltaic cells. Solar hot water heating has been in use for centuries, and is lately more directly used in roof-mounted fixtures, and solar space heating goes back a long way too. (Check out cliff-dwellings in American southwest, for example, carved into south-facing slopes to take advantage of the low winter sun, and with overhangs to screen the high-angle summer rays. Today’s green builders use the same technique.)

But photovoltaic cells are a game-changer, providing direct conversion of the sun’s energy into electricity which can be directed down the wires to power pretty much anything we think of as “modern.”

Here in Asheville you will soon be AMAZED by a program of the Blue Ridge Sustainability Institute, dubbed “Solarize Asheville,” which will help homeowners work together to contract, install and pay for rooftop solar installations. It’s coming soon to a neighborhood near you. Stay tuned.

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Cecil Bothwell is author of nine books, including “She Walks On Water: a novel” (released this month),  and a member of Asheville City Council.