The Call, Column 49 – The Future Looks Bright: The Age of Renewable Energies

31 07 2016

(June 19, 2016)

The Urban Farmer

The Future Looks Bright: The Age of Renewable Energies

I’ve written almost no columns about renewable energy. That is the stunning realization that I made this morning, while brainstorming a topic for this week’s column. I wrote a little about solar energy a few years ago, about nature’s material and energy cycles last spring, and a few times about climate change over the years. But we have never actually discussed the interesting science behind the wide array of renewable energy technologies that are coming onto the market, or their amazing value to urban farmers, environmentalists, and homeowners alike. Given that energy technology was basically the motivating topic of my electrical engineering degree, you can probably appreciate how surprising it is to me that I haven’t written more. It’s time to change that.

Today’s column will be a briefer on renewable energies in general. And in the coming weeks, we’ll address each type of renewable energy – solar photovoltaic, solar thermal, wind, geothermal, tidal and wave, hydropower, biofuels, and wood – at their various scales of implementation. As quick primer: a watt-hour/BTU/joule/calorie (with any prefix, i.e. tera/giga/mega/kilo in front) is a unit of “energy”, the capacity of a system to do some physical “work” (movement, heat, light/radiation, chemical reaction); whereas a watt is a unit of “power”, a measure of energy-flow per second. So when we speak of total energy usage or storage, we use the first one (i.e. my electricity usage was 500 kilowatt-hours this month), whereas when we talk about the energy continuously used or transferred by something, we use the second one (i.e. my smartphone uses 4 watts). With all of that said, let’s get to answering the question: What are renewable energies?

There is nothing new under the Sun. This verse from Ecclesiastes is my favorite quote, probably because of how it beautifully it underlies the entire study of agriculture, the environment, and economics. Our Earth is a closed-system chemical reactor, which consists of basically the same physical materials that it did at its Creation, 4.5 billion years ago. And in terms of energy, other than the small contributions from the nuclear reactions in the Earth’s core (about 0.027% of the total) and other astrophysical phenomena, essentially every single bit of energy that enters the Earth’s atmosphere comes from one source: the Sun.

Solar energy drives every natural process on the surface of the Earth, called the biogeochemical cycles (of carbon, oxygen, nitrogen, water, and rock). The comingling of these material cycles produces the non-biological natural phenomena that we experience on a daily basis – wind, rain, evaporation, humidity, flowing water, and weather events of every type – which makes them all indirectly solar-powered. And the direct influx of sunlight, together with these cycles (indirect sunlight), is also the sole energy source for pretty much all of Life on Earth, from the smallest microbe to the blue whale, and every plant, animal, fungus, protozoa, and bacteria in between (with the notable exception of certain deep-sea and volcanic ecosystems, which utilize the Earth’s geothermal heat as their driving energy).

And because we have no say in the matter, as biological organisms bound to the surface of the Earth, everything that we humans do is powered by the Sun as well. Did that catch you off guard?

You see, the Earth has this rather curious ability to store small amounts of sunlight. This is underlain by the process of photosynthesis, where plants, fungi, protozoa, and bacteria convert sunlight into chemical energy. These energy-containing chemicals circulate through the Earth’s ecosystem, and over long timescales, a small fraction of them are converted by geological processes into hydrocarbons, stored deep in the Earth’s crust. That’s right: even fossil fuels are sunlight, from a very long time ago.

And that, readers, is where we went wrong. Ever since we discovered that certain rocks could be burned, but mostly over the past 150 years of economic explosion, we have built up our global society by depleting the limited stores of ancient solar energy that we suck out of the Earth’s crust. That energy took hundreds of millions of years to store, and in the span of seven generations, we have used a good majority of it. It’s been used, of course, to drastically increase agricultural production and general quality of life (and, therefore, survival rates), thereby growing our population by nearly six billion people (a factor of about 6) in 150 years, about 0.000002% of our time on Earth. And in using it at such a rate, we’ve released huge swathes of stored carbon dioxide into the atmosphere, triggering dangerous global warming in the process (scientific fact which needs no further justification).

In retrospect, that may not have been the best idea. But it happened, and there’ll probably be 10 billion of us to feed, clothe, shelter, and keep warm right about the time when the oil wells run dry and the effects of climate change become a serious threat to our survival. Oh well…as long as someone profited handsomely, I’m cool with that.

Just kidding. Well, not about the oncoming end of the Age of Petroleum; no, that’s definitely something we have to look forward to. But I’m kidding about my contented acceptance of our self-inflicted, greed-driven fate as a result. That’s not going to happen if we have anything to say about it.
You see, the ball of fire in the sky continuously dumps 173,000 terawatts of power (on average) into the Earth’s atmosphere, a bit over 14,000 times as much as is used by all of human society. That is contemporary solar energy (in stark contrast to the dinosaur juice we currently use to power our lives), and we see it every day in the sunlight, the wind, the flowing of freshwater, the movement of the tides and ocean currents, and in the foods we eat and wood we burn. Wait, don’t those sound familiar? Solar, wind, hydro, tidal, bio…those are the various forms of solar energy that we find on the surface of the Earth, and also happen to be the various renewable energy technologies available.

That’s clearly no accident. The following renewable energy technologies have been developed to tap into the various forms of contemporary solar energy, which will be free and available forever, without harming the Earth’s environment or further ballooning our dependence on dirty, finite resources.

Solar photovoltaic panels use silicon semiconductor technology to convert sunlight into electricity. Solar thermal systems use air, water, or other fluids to capture sunlight as heat energy, which is used as heat itself, or to run a turbine that generates electricity. Wind turbines use rotating generators to convert the energy stored in moving air into electricity. Tidal and wave generators convert the energy stored in moving ocean water into electricity. Hydropower systems similarly turn the energy stored in moving freshwater bodies into electricity (i.e. hydroelectric) or mechanical energy (i.e. water wheels). Biofuels, like wood burning, anaerobic digesters, algal biofuels, and ethanol generators, employ various chemical and biological mechanisms to convert the chemical energy produced by photosynthesis into various forms of usable chemical energy (i.e. equivalents to natural gas and other hydrocarbons), or directly into heat. Geothermal systems are the only renewable energy technology that is not solar-powered, but instead utilizes the heat energy escaping from the Earth’s core to either produce electricity or as heat itself.

There is a huge variety of very powerful renewable energy technologies at our disposal. This diversity, if we take full advantage of it, will help to prevent us from falling into the same trap in which we currently find ourselves, over-dependence on one technology. Most of these technologies are well into their maturity, ready to be implemented as desired. In the coming weeks, we’ll look at each of these renewable energy technologies in detail: its science, benefits, drawbacks, and current state of implementation, as well as what we as urban farmers can do to get involved. At some point, we’ll also talk about the operation of the electric grid, (including the fact that renewable energies actually reduce the price we pay for electricity), and how these technologies fit into our economies at every level. This is probably my favorite topic to write (and talk) about, so I look forward to exploring it together with you.

My column appears every other Sunday in The Woonsocket Call (also in areas where The Pawtucket Times is available). The above article is the property of The Woonsocket Call and The Pawtucket Times, and is reprinted here with permission from these publications. These are excellent newspapers, covering important local news topics with voices out of our own communities, and skillfully addressing statewide and national news. Click these links to subscribe to The Woonsocket Call or to The Pawtucket Times. To subscribe to the online editions, click here for The Call and here for The Times. They can also be found on Twitter, @WoonsocketCall and @Pawtuckettimes.