Simanaitis Says

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THE TERM “renewable resource” gets bandied about a lot. Indeed, I’ve been party to such bandying in discussion of California’s electricity and its sourcing. Most people think of hydro power, wind farms and solar panels as renewables. However, there are others. And, wouldn’t you know, political correctness gets involved in definitions of what is—and isn’t—renewable. These definitions matter, especially when comparing region to region and, for example, the U.S. to the European Union.

I’ve gleaned a lot of information from a variety of internet sources. Maybe those of you in other parts of the country, and world, can share appropriate definitions.


The Grand Coulee Dam on the Columbia River in Washington opened in 1942 after nearly nine years of construction. Image from the U.S. Bureau of Reclamation.

Let’s begin with hydroelectric power, an historic resource. The Grand Coulee Dam, largest such facility in the U.S., and others like it convert the kinetic energy of flowing water into electricity. No water is used up in the process and, in fact, such large-scale hydropower is defined as renewable by the U.S. Environmental Protection Agency.

However, both within other levels of government and outside it, dams are perceived as harming the environment. California, for instance, makes a distinction between “large” and “small” hydropower, with the renewable cutoff set arbitrarily at 30 Megawatts. Large hydro doesn’t count in a calculation of the state’s Renewable Portfolio Standard, its RPS.

As a rough guideline, 1 MW supports perhaps 1000 homes. Thus, a small renewable hydropower facility, a turbine in a stream, for example, might support a community of 80,000 people.

There’s a variety of RPS hydropower tallying around the U.S. For instance, Michigan and Missouri count existing hydropower of any size, but not new dams nor expansion of old ones. Ohio’s RPS counts any facility as long as it’s not deemed harmful to fish, wildlife and water quality (though one suspects it may affect costs of litigation).

In 2012, a bill was proposed in the California State Assembly to include large hydro in its RPS. Because of pressure from the Sierra Club and other environmentalist groups, the bill died in committee.


A California power budget for 2014. Image from California Energy Commission Energy Almanac.

So, in fact, when considering renewables, there’s hydro power—and hydro power. In 2014, hydro contributed 6.4 percent of California’s Total System Power, most of this from large hydro (5.5 percent). That is, renewable small hydro contributed less than 1 percent of the total.


Geothermal is the second largest renewable resource in California (only wind is larger). Image from the Geothermal Education Office.

Geothermal energy is perhaps a less familiar renewable, relying on the immense heat emanating from the Earth’s core through its mantle into its crust. California is rich in geothermal resources, responsible for 4.4 percent of the state’s electrical power. In fact, geothermal makes up 12.2 percent of the renewables category, second only to wind power.


The Altamont Pass Wind Farm, near Livermore, California. Image from the California Energy Commission.

Wind farms are responsible for 8.1 percent of California’s total electrical supply, 40 percent of the renewable category. The other renewables are solar at 4.2 percent of total and biomass (cogeneration from garbage, for example) at 2.5 percent.

Solar has a quirk in RPS figuring too. Only large solar arrays producing 1 MW or more are included. Home and most other roof panels do not count. There’s irony here: Huge solar arrays affecting acres of desert wildlife get the RPS nod; environmentally unfriendly dams do not.

A word about non-renewables, natural gas and, the Antichrist, coal. California electrical utilities are heavily into natural gas, 44.5 percent of total. Because of environmental aspects (strip mining, slag heaps, acid rain, CO2 and the rest) coal has dwindled to 6.4 percent of total (though it’s still ahead of any renewable except wind).

Last, there’s the matter of “imported power.” Electrical grids are highly interlaced, in part to allow balancing of supply and demand. Unlike water that might be saved up, electrical utilities don’t store current for later use in the long term.


A slightly different view: California Electrical Energy Generation by Resource Type. Data derived from another Energy Almanac chart.

For example, in 2014 California depended on imports for 33 percent of its electrical energy generation. Of these, 4.2 percent are termed “Direct Coal Imports.” For example, the Modesto Irrigation District (handling both water and power) imported 14 percent of its electricity from a San Juan, New Mexico, facility that’s coal-fired. (The deal ends in 2017).

The remaining 28.8 percent of total termed “Other Imports” includes a coal-fired facility in Utah, a geothermal one in Nevada, a pair of natural gas facilities in Mexico and “others.”

Also, in the Energy Almanac’s Total Electrical System Power chart (see “California Power Budget” above), its “Unspecified Sources of Power” category includes Northwest Imports and Southwest Imports comprising 15.0 percent of the California Power Mix.

No wonder Renewable Resource is such a hazy term. ds

© Dennis Simanaitis,, 2015


  1. Mike B
    September 17, 2015

    If I were the King of the World … I’d define “renewable” as anything that doesn’t involve mining or fossil fuels in general to power it. As a practical matter, it would all be directly or indirectly solar-powered (wind & hydro & bio-whatever are indirectly solar).

    Geothermal is a grey area – it’s depletable on a geologic time scale, unless it relies on a water supply which *is* depletable short-term. The Geysers project in California was in trouble some years back until a couple of sewer systems started injecting treated wastewater there (instead of dumping it into waterways), which triggers a lot of small earthquakes but stabilized the steam production.

    There might be levels of desirability for various renewable sources, like large v. small hydro, based on side effects. That distinction is important, but it doesn’t render the source non-renewable. We need to keep big hydro, for instance, for its grid impact and (relative) reliability – with a large lake behind the power plant, it can usually produce the nameplate output for a full year (ignoring long-term droughts) rather than whenever the creek runs. And you pretty much need big hydro for pumped storage – presently the only way to store grid electricity in useful amounts. Biofuels of various types, also, have side effects including toxic emissions (which have to be controlled – same concept as for fossil fuels) when burned. Again, none of that makes them non-renewable.

    Nuke is interesting. Definitely not “renewable” in that the fuel is mined. And it’s qualitatively different in that the fuel is, ultimately, destroyed by transmuting it into something that can no longer be used conveniently. Chemical reactions, on the other hand, don’t fundamentally change the elements involved.

    Funny thing: fossil fuels technically *are* renewable. It’s just that the time scale involved for producing them (seriously geologic) is so far beyond human lifetimes that it’s irrelevant. They’re really very indirect solar power – we’re burning plants that grew some tens to hundreds of millions of years ago.

  2. Michael Rubin
    September 17, 2015

    Nothing clear yet on the impact, but part of the Calpine geothermal facility in the “Geysers’ project was damaged by the still burning Valley fire, which crossed from Lake County into Sonoma County. The facility itself is quite near Cobb, a small village destroyed by the fire.

  3. Mike B
    September 17, 2015

    Regarding the Calpine damage, the newspaper articles I saw said that one of the plants took some damage to a cooling tower, but the rest of it was OK. Geysers isn’t just one plant – it’s more than 1/2 dozen scattered over the hills, so if only one was only partially damaged I’d expect only minor reduction in output.


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