The Hempster's Stitch: Eco basics

For as long as our planet has spun 'round the sun, there's been solar energy cascading down on the earth, and, for a long time -- since the 7th century B.C., when glass was used to magnify it -- humans have been working to harness it. These days, technology is a bit better, providing electricity, heating, lighting, and even flight, but the point is the same: use the sun's warm glowing warming glow for our benefit.

Often used synonymously with solar energy, solar power is what you've got once the sun's energy has been converted to electricity. This can be done one of two ways: heating a liquid to produce steam and spin a generator, or through photovoltaics (but that's another post). For now, we'll concentrate on how to use the massive and largely untapped potential that exists with solar energy. But first, some basics.

Short answer: the light and heat provided by the sun. A slightly longer answer: after running the gauntlet from an average of 93 million miles away, through the various layers of atmosphere and atmospheric conditions (clouds, pollutants, dust and the like), about half of the solar energy is absorbed by water and land, with the other half reflected and re-radiated back into space. The half that makes it is absorbed by oceans, land masses and plants; in the ocean, the energy drives heat and wind-driven currents (like the Gulf Stream); on land, the energy is absorbed and creates heat, and the little bit that's left is absorbed by plants and converted to chemical energy through a process we all know as photosynthesis.

Outside of the three scenarios above, solar energy usually requires a little human input to really work (photosynthesis, which helps grow crops for food and fuel, is a notable exception). This help can come in lots of different forms, from architecture and urban planning, which uses techniques to maximize light and heat from the sun to our benefit in our buildings, to solar thermal, the most widely used category of solar energy technology, including solar cooking, water distillation and purification and lots more, to heating water for our use and desalination.

But, by far, solar energy's most talked-about use is electricity generation. For now, photovoltaic (PV) cells and panels remain the most-used method for turning sun into electricity. Basically, photovoltaics cause photons from sunlight to knock electrons into a higher state of energy, creating electricity. Photovoltaic production has been doubling every two years, increasing by an average of 48 percent each year since 2002, making it the world’s fastest-growing energy technology.

But it's not alone in the solar world; concentrating solar systems use lenses, mirrors and tracking systems to focus a large area of sunlight into a small, concentrated beam, which is then used to generate electricity. This can be accomplished using a trough system; by allowing direct sunlight to hit troughs, the solar collectors concentrate it into a single area that boils liquid in order to make steam, which in turn moves turbines to make electricity. This up-and-coming technology can be made even more efficient with the use of a solar tower, which is just what it sounds like: a tower that uses careful sun tracking to concentrate solar energy near its top. There are various other technologies that can create solar power from solar energy, but, for now, these remain the most popular and most viable.

Solar's biggest advantage is that there's so much of it. The total solar energy available to the earth is approximately 3850 zettajoules (ZJ) per year, while worldwide energy consumption was 0.471 ZJ in 2004, according to the US Department of Energy. Even if you aren't a solar panel installer, you can tell that there's way more solar energy available than the world will ever need. Solar energy is also terrifically versatile; as we mentioned above, it can be used to help grow food and fuel, light, heat and modulate the temperatures in our homes, disinfect and desalinate water, and more. And, once you figure out how to best maximize the available energy, solar is the gift that keeps on giving; as long as the sun doth shine, solar energy will be available for its myriad uses.

Solar energy's disadvantages can be pretty well boiled down to one thing: cost, at least for using it as electricity. It takes a lot of land and costs a lot of cash to be worthwhile, as most types of solar cells require large surface areas to achieve average efficiency, and the silicon used in many of today's cells is also very expensive. Pollution and weather can further cut back their efficiency, which, of course, increases the cost over time.

And though solar energy will always be available on a macro scale, it isn't always available on an hour-to-hour scale, because it doesn't work when the sun isn't out (which always happens at night and sometimes happen due to weather). Storing the energy in batteries for use during these times cuts back on the efficiency further. And, of course, if you live somewhere that doesn't have good solar energy exposure, there isn't much you can do. You gotta have the sun.

In addition to metrics like ecological footprint, each of us (and each of the products and services we use and consume every day) has a carbon footprint; it's a way to measure the relative impact of our actions -- as individuals, as businesses, communities and countries, as we eat, work, travel, play, etc. -- in terms of the contribution made to global climate change. Measured in carbon emissions (usually in pounds, tons or kilograms), it's become an increasingly useful and popular tool to help contextualize global warming in our daily routines and lives.

What is a carbon footprint?
A carbon footprint is the total amount of carbon dioxide (CO2) and other greenhouse gases emitted over the full life cycle of a product or service, and everything has one, from the computer you used to find this article to the next meal you eat (and the one after that, and after that, and so on...) to the shoe that will leave a physical footprint on the ground the next time you walk outside. But that's only part of the story.

Calculating carbon footprints
First of all, carbon footprints can be calculated in one of two ways: using a Life Cycle Assessment (LCA) method (more accurate and specific), or it can be restricted to the immediately attributable emissions from energy use of fossil fuels (more general). To use your car's carbon footprint as an example: the first method would take into account all carbon emissions required to build the car (including all the metal, plastic, glass and other materials), drive the car and dispose of the car; the second would account only for the fossil fuels that resulted from building, driving and disposing of it.

Further, there's more than one way to run the numbers, depending on how they're going to be used. Top-down calculations, like those done in the world map above and the US state map below, that calculate per capita carbon footprints, take total emissions from a country (or other high-level group, organization, etc.) and divide these emissions among the residents or otherwise applicable group. Bottom-up calculations, like with your car's carbon emissions from the example above, sum attributable carbon emissions from individual actions.

Okay, so everything has a carbon footprint, and each can be measured a couple different ways, but it's not just a matter of carbon dioxide, though that is the most common of greenhouse gases (GHGs) other than water vapor; other GHGs include (but aren't limited to) methane, ozone, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons (see the IPCC list of greenhouse gases for a more thorough list). Given this, still, most carbon footprint calculations include all applicable gases, as they all contribute to the greenhouse effect and our persistently warming globe.

"What is my carbon footprint?" Calculating your own footprint
Though a fairly complex calculation, with many variables that are different for each person, carbon footprint calculations generally include energy used to power our homes and transport, including travel by car, airplane, rail and other public transport, as well as all the consumables we use on a regular (and irregular) basis; many of the individual factors above can be calculated separately (e.g. an individual carbon footprint for your home, travel, food, etc.). Once you understand what goes in to your carbon footprint, and, probably more importantly, what your carbon footprint is, you can start reducing it; indeed, for as many ways as there are to create a carbon footprint, there are ways to reduce it.

Increasing the efficiency of our energy use, reducing our energy use and changing a few habits (like eating less meat, eating more local food, not traveling by airplane as much) are some of the quick, easy ways to cut back on the size our individual carbon footprints.

Where do carbon offsets fit in carbon footprints?
After increasing efficiency and reducing use, carbon offsets are also an increasingly popular (and increasingly controversial) way to help mitigate our carbon footprints -- see TreeHugger's How to Green Your Carbon Offsets guide for more on that. But the point remains: there are many, many ways to reduce and even eliminate your carbon footprint; most every article you'll read on TreeHugger will be related to carbon footprints and emissions, though some more directly than others.

by Jill Connors

on 02.18.09

With fuel prices and consumption dominating the news—not to mention our country’s future energy policy—we offer a quick primer on the complex subject of offshore drilling. How much oil do we currently produce from offshore drilling, and how much might we potentially recover? What’s the status of the moratorium banning offshore drilling in various areas? What are the environmental risks? And perhaps most importantly, what is the psychological impact of thinking that offshore oil holds promise as a source of abundant, less-expensive oil when nothing could be farther from the truth?

Offshore Drilling: Background Info

The term offshore drilling refers to the extracting of oil from fields that lie beneath the ocean floor, anywhere from a few hundred feet to 200 miles off the coast. The first offshore well was drilled in 1887 from a wooden wharf off Summerland, California; technology improvements have made it possible to drill in deeper water and farther from shore ever since. Today, some 4,000 platforms operate in the U.S. federal waters in the Gulf of Mexico, primarily off the coastlines of Louisiana and Texas, and off the coast of Alaska, producing approximately 565 million barrels of oil per year, according to the U.S. Energy Information Administration's overview of offshore activity. U.S. offshore oil production of 565 million barrels per year equates to roughly 1.5 million barrels per day; contrast that figure with U.S. current oil consumption of 21 million barrels per day.

Offshore Drilling: What’s the Fuss

The debate about offshore drilling stems from questions over how much oil potentially could be recovered from underwater fields versus the time and cost, both in dollars and environmental impact, related to that process. Common misperceptions notwithstanding, the debate does NOT stem from notions that offshore drilling could eliminate U.S. need for foreign oil (at current consumption, the U.S. uses 8 billion barrels of oil per year; conventionally recoverable oil from offshore drilling is thought to be 18 billion barrels total ever—not per year). The debate does NOT stem from notions that offshore drilling would guarantee lower fuel prices (oil is a global commodity, and U.S. production is not big enough to influence global prices).

by Jill Connors on 02.18.09

Offshore Drilling: Background Info

Offshore Drilling: What’s the Fuss

Offshore Drilling: Environmental Risks

Offshore Drilling: The Moratorium

Offshore Drilling: False Hope

Offshore Drilling: Facts and Figures