We Must Reduce Energy Use, Not Just CO2 Emissions, To Prevent Catastrophic Global Warming

playing with fire
Playing With Fire (image by charles chan, CC 2.0 license)

An article in Sunday’s Science Daily reports on research showing that more than half of the Earth’s warming since the dawn of the industrial age is due to the heat released from our energy use, not atmospheric warming due to the greenhouse effect.

While the greenhouse effect is still a significant contributor – and will become more so as GHG levels in the atmosphere rise – simply the heat released when burning fuels is also being stored in the atmosphere, as well as in the earth, sea, and arctic ice.

The researchers have calculated that the heat energy accumulated in the atmosphere corresponds to a mere 6.6% of global warming, while the remaining heat is stored in the ground (31.5%), melting ice (33.4%) and sea water (28.5%). They point out that net heat emissions between the industrial revolution circa 1880 and the modern era at 2000 correspond to almost three quarters of the accumulated heat, i.e., global warming, during that period.

Their conclusion is that simply capturing our CO2 emissions, will not prevent global warming. We have to actually reduce the amount of heat we are releasing into the world via our energy use – which mostly involves burning things, and therefore generating waste heat.

The good news is that solar photovoltaics, wind power, even solar thermal generate much less, or even negative, waste heat than either conventional energy sources, or nuclear energy. And of course energy efficiency is the cheapest and most cost-effective mitigation we have at our fingertips.


Running Gore’s Numbers: An Edifying, If Simplistic, Analysis

Photo: Bill Gantz
Photo: Bill Gantz (Creative Commons License: Some Rights Reserved)

In his galvanizing speech a few weeks ago Academy Award and Nobel Prize-winner Al Gore exhorted the United States to “produce all electricity from “carbon-free sources” by 2018.” This is a pretty abstract goal, in those terms – Gore (appropriately) didn’t go into great detail about how this should be done or even what it means in specific practical steps. Depending on your point of view and background knowledge about energy, the goal may seem easy or incredibly difficult, or even impossible, especially without further analysis.

So I thought it would be interesting to run some numbers on the goal. The idea is not to define how it should be done, but to look at some very simple scenarios for how it could be done to get a sense of the scale involved. The calculation is based on the Topaz Solar Farm project, which California’s PG&E utility just contracted for – a 550 megawatt solar generating station.

My initial calculations makes some gigantic simplifying assumptions, so it’s not “correct” – but it should be the right order of magnitude. For details of the calculation, see the analysis below. The conclusion is as follows:

As a very rough estimate, we would need about 800 Topaz-sized plants, total cost about $1 trillion, to meet the U.S. electricity demand. And it would require about 8,000 square miles of sunny land.

The Key Parameter

Gore’s goal is equivalent to saying “We need to be able to generate on the order of 400 GW of electricity from carbon free sources.”

A few other useful or interesting numbers:

  • 550 megawatts: Generating capacity of the Topaz Solar Farm, one of two new solar electric plants PG&E is building in the California desert, announced a few weeks ago
  • 9.5 square miles: Size of the Topaz Solar Farm
  • $1 billion: Cost of the Topaz Solar Farm
  • 1 gigawatt: Generating capacity for a “large” coal-fired generating plant
  • 50 GW: California’s typical peak energy demand
  • 24%: portion of PG&E’s currently contracted generating capacity that is renewable


For the purposes of this analysis, I’m making a few simplifying assumptions. These make the analysis “invalid” from a technical sense, but allow us to quickly see the big picture:

  • Electricity demand will stay constant: This may or may not happen – in California energy intensity (the energy used per person) is going down, and this summer absolute energy use went down. Amory Lovins of the Rocky Mountain Institute believes we can cut energy intensity by 50% via efficiency, which would definitely cut energy use. On the other hand, most scenarios dealing with energy use assume it will continue to grow.
  • Disregard base load issues: The sun don’t shine at night, but people still use electricity then. This is called “base load.” You often hear that “solar can’t provide base load,” which may or may not be true in the future, depending on storage technologies that might be developed. In any case, I’m not considering it in this analysis – I’m assuming “a megawatt is a megawatt.”
  • Disregard transmission issues: We’ll assume that if the energy is generated somewhere in the U.S., it can be used anywhere else it’s needed.
  • Disregard technology improvements – this calculation is based on the technology planned for the Topaz Solar Farm

First cut

We now have enough data to make the most simplistic conceivable analysis. How many Topaz Solar Farm equivalents (TSFs) would we need to supply total U.S. energy demand (given the assumptions above)?

Total demand = 400 GW

TSF = 550 MW

Demand/capacity = 400 GW/550 MW = 800 (number of plants needed)

Cost = 800 * $1 billion = $1 trillion (approximately)

Conclusion: In our simplified energy world, we’d need about 800 Topaz-sized plants, total cost about $1 trillion, to meet the U.S. electricity demand. And it would require about 8,000 square miles of sunny land.

Now, there are many ways that this analysis is “wrong” – since my assumptions simplify the world quite a bit. So it could easy be off by a factor of 50% or more. But, because the assumptions also tend to cancel each other out, it’s not off by a factor of five, say. For example, I’m not considering base load (which solar PV today can’t provide effectively), but on the other hand, solar PV is the most expensive energy source. We will probably need more than 800 plants, but a lot of them will be cheaper, per megawatt, than the Topaz Solar Farm.

In future posts I will expand this model to make it less simplistic and more realistic, and to take into account technology improvements, base load requirements, the ability of energy efficiency to change the demand line, and lots of other details that are just dropped on the floor for this analysis.

I’m very interested to hear your comments on this analysis. In particular, I hope for some constructive guidance on the next steps for making it more realistic. I want a simple model that’s easy for the layperson to understand, but which doesn’t over-simplify too much (as this model does). I’d consider this a “zero-order” approximation – the next one should be a “first-order” approximation.

Other reading

  • The New York Times’ Dot Earth blog posted the text of Gore’s speech and allowed commenters to annotate it – interesting reading if you have a few hours to get through all the comments!
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Efficiency profitable for energy-independent Denmark

Thomas Friedman’s OpEd on Sunday describes how Denmark has achieved energy independence, and illustrates the numerous benefits for the country, including a very low unemployment rate and a large new export market.

When the 1973 oil shock hit, Denmark got 99 percent of its energy from the Middle East. Now they get zero. The country has combined massive energy efficiency programs, such as using waste heat from power plants to heat homes (known as “cogeneration”), with alternative energy sources like windmills (20% of their energy comes from the wind now), effective use of their own petroleum resources in the North Sea, and incentives for lowering energy use via high taxes on gasoline.

As a result, Danes enjoy one of the highest standards of living in the world, an extremely low unemployment rate, and a healthy export sector in alternative energy products.

Because it was smart taxes and incentives that spurred Danish energy companies to innovate, Ditlev Engel, the president of Vestas — Denmark’s and the world’s biggest wind turbine company — told me that he simply can’t understand how the U.S. Congress could have just failed to extend the production tax credits for wind development in America.

Engel suggests why this might concern us here in the United States.

“We’ve had 35 new competitors coming out of China in the last 18 months, and not one out of the U.S.”

If Denmark has been able to achieve 100% energy independence, at net benefit to their society economically, what does that say about America’s chances? Denmark has some advantages – it’s much smaller than the U.S., it has new oilfields in the North Sea – but we have advantages as well – our Southwest is much better for solar than anywhere in Denmark, we have whole states available for wind power, we have comparatively high rates of energy inefficiency that represent massive “negawatts.” Amory Lovins of Rocky Mountain Institute has outlined a set of steps for getting the U.S. off oil by 2025 – Winning The Oil End Game – that provides one possible, well-researched scenario for a profitable transition.

In the 35 years since the ’73 oil shock, Denmark has accomplished something remarkable. Now we in the U.S. need to set ourselves a similar goal. Using new technologies, such as the fuel cell breakthroughs I mentioned last week (here and here), we should be able to get there a lot faster than 35 years.

Is this solar energy analysis is too simplistic?

According to this analysis from Clean Edge, (which I saw originally in the San Jose Mercury News, Solar energy cost may rival other forms soon, study says – SiliconValley.com):

Solar energy will cost the same as power produced by coal, natural gas and nuclear plants in about a decade, a report released Tuesday suggests. By then, the price parity could propel solar adoption so that it accounts for 10 percent of U.S. electricity generation by 2025

If you listen to this kind of thinking, solar energy (which is defined as what, by the way?) is still far more expensive than other kinds. But solar energy, even today, has a finite payback time – if I put solar collectors on my roof, for example, eventually they will pay for themselves.

So that’s one way it’s wrong.

Secondly, the study assumes that conventional energy prices will go up by 3% per year. That could be a slight underestimate. Didn’t we just experience a three month period where gas prices nearly doubled? (That’s 100%, folks!).

I can’t make any argument about the assumption that solar energy prices will come down 18% per year. That’s a lot, by one metric, but we’ve certainly seen large and faster price drops in high tech in the past. Even the iPhone last month, which dropped in price by almost 50% in less than a year. Sure, that was partly through some magic AT&T financial pixie dust, but to the user, it’s a clear 50% price cut. There’s no reason similar magic pixie dust, whether from the government or from the utilities themselves, won’t contribute to market price declines.

The claim that solar currently accounts for less than 1/10th of a percent of the U.S. energy supply today is fine. But the assumption that it will still be less than 1 percent in 2015 (seven years from now) is curious. If we start at .1 percent, and double our solar usage every year, we end up at 128 times as much – 12.8% of today’s total. This is the amazing power of Ray Kurzweil’s “Law of Accelerating Returns.” Even if it takes two years for each doubling, we’re still up a factor of 32x in seven years. That means 3.2% today’s usage. Our total energy usage may also go up (although there are very good reasons to think it may not go up much and and will be starting a downward trajectory), but for a 32x increase in solar supply to translate to 1% of our total energy use, total energy use would have to double. Not too likely in the U.S., where population growth has stopped, and SUVs are starting their long decline.

Finally, there’s good reason to believe that solar energy will actually have a much larger share of U.S. energy usage, due to the power of “negawatts” (as explained brilliantly by Amory Lovins in this series of talks at Stanford in 2007), in which efficiency turns out to be the most cost effective way to power industry and create profits. Oh, and by the way, it significantly reduces our energy usage, by as much as a factor of five to seven!

The article combines a couple of types of fallacious thinking – that technological progress is linear, for example, rather than geometric, and that other factors, such as the desire to reduce greenhouse gases or realizing the benefits of negawatts throughout the economy, don’t have an additional accelerating effect on technology changes.