Quantitative Environmentalism: Solar Energy, Wind Energy, & Desalnisation Calculators

Absent a rigorous examination of statistics, meaningful dialogue about environmental issues is impossible. This is particularly challenging now that environmentalism is generally recognized to be inextricably linked not only with the endlessly complex science of ecology, but with the dismal science of economics as well. To try to quantify the rational basis for a legitimate ideology of environmentalism is not easy.

One way to productively further the dialogue of rational environmentalism is to publish online interactive calculator of hopefully instructive simplicity, quantitatively presenting options in terms of costs and benefits for environmental issues management. To this end, we have recently added two new online interactive calculators, Wind Energy per Area and Solar Energy per Area.


In both cases the user may calculate the area required to set up solar fields or wind farms that will generate meaningful quantities of electricity – power sufficient to electricify entire cities, if not the entire world – in this dawning electric age. Because solar and wind power are intermittant, users are provided the input “yield” (constant percent of maximum output) in order to come up with the unit termed “constant gigawatts,” which refers to the average continuous output into the grid from a solar or wind generating source. For example, an entire year of 1.0 constant gigawatt output would constitute one gigawatt-year, or 8.8 billion kilowatt-hours.

What is quite interesting in the case of wind and solar energy is that using these calculators, wind farms and solar fields appear to require about the same amount of area to produce a given amount of electricity. If you assume a wind farm consists of 2.5 megawatt, 25% yield turbines on towers 125 meters high and 250 meters apart, you will find, using our spreadsheet, that a constant output of 1.0 gigawatts of wind energy will require a wind farm 100 square kilometers in area. Similarly, our solar calculator indicates that for a solar field to generate a constant energy output of 1.0 gigawatts, an area of 99 square kilometers would be required. This virtually equivalent area is based on assuming a 1.0 square mile solar field putting out 150 megawatts in full sun – a reasonable expectation – with a yield of 17.5%.

The world’s first 5.0 megawatt wind turbine, operating since
2004 on the southwest coast of Schleswig-Holstein in Germany.
(Photo: RE Power)

Using this reasoning, when you compare the area of the planet required to replace conventional fuels with solar fields vs. wind farms, wind and solar become interchangeable variables. So how much area of solar fields (or wind farms) would be required for their output to fulfill 100% of the world’s current energy requirements? In our online spreadsheet “Global Energy 100% Solar,” we cite as the default assumption a total annual global energy consumption of 500 quad BTU – (500 quadrillion “British Thermal Units,” the amount of energy required to heat one cubic centimeter of water 1.0 degrees centigrade – 1,400 BTUs = 1.0 kilowatt-hour, 125,000 BTUs = 1.0 gallon gasoline). In reality, as within fifty years when human population begins to decline from some maximum total of well fewer than 10.0 billion people, human energy consumption will probably also max at around 1,000 quad BTUs. If you input 1,000 quad BTUs and 5 watts per square foot – (the utility scale wind and solar energy production density), then using wind/solar for 100% of future total world energy production (roughly 2x today’s) would only require an area of about 40,000 square miles (a square area only 200 miles on a side), or 100,000 square kilometers!

When you consider biofuel, using our “Global Energy 100% Biofuel” online spreadsheet, inputting the relatively generous 100,000 BTUs per gallon and 25,000 barrels per square mile per year (42 gallons per barrel), at 1,000 quad BTU (2x current global energy production), you will see that this amount of annual energy harvest will require a land area of 9.5 million square miles (24.6 million square kilometers). Don’t write off biofuel – land is abundant, and biofuel can be plentiful, cost effective, and sustainable. In most cases to-date, far lower capital investment is required for biofuel compared to wind or solar. Nonetheless, we welcome anyone verifying these figures – did we drop three digits again?

Our favorite new online spreadsheet is “Bulk Water Lift – Energy Required,” which assists users to calculate the costs and benefits of interbasin water transfers. We have reported on this in our articles including “Interbasin Water Transfers,” and Refill the Aral Sea. Other areas where interbasin water transfers could be quite environmentally helpful include north from the Ubangi River to Lake Chad in Africa. And of course the fine example of California, struggling to upgrade what is already the biggest and most modernized bulk water transfer system in the world, where, among other things, about 6.0 km3 of fresh water runoff from the north flows 500 miles south and over a 1,500 foot lift to nourish the Los Angeles basin. And along with this new spreadsheet, by all means investigate our already posted “Desalination – Cost per Household.” You will note the energy required to desalinate water is actually less than the energy required to lift it 1,500 feet!

Quantitative Environmentalism, often surprisingly, can help reveal realms of innovative and green possibilities in all their competitive and compelling feasibility. Perhaps the most productive quality of all is the ongoing and consistently credible, plausible, positive and optimistic oeuvre of prognoses that may issue from the perspective of quantitative environmentalism.


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