Real Science

Saturday, 11 August 2007

Renewables fail

Rockefeller University, New York: 25-Jul-2007 01:00 Eastern US Time

Renewables fail environmental test

Renewable does not mean green. This is the surprising result of research done by Professor Jesse Ausubel of Rockefeller University, New York. We might be able to build enough wind farms to produce all the energy the world needs, he says. Or dam enough rivers. Or grow enough biomass.

But we will wreck the environment if we do.

Ausubel worked out the power each kind of renewable energy produces for a given area of land that it disturbs. In other words he calculated power per square metre.

He showed that renewable energy needs enormous areas of land. He compares the destruction of nature by renewables with the space needed by nuclear power.

Nuclear energy is green," he says. "Considered in watts per square metre, nuclear has astronomical advantages over its competitors." His research appears in Inderscience's International Journal of Nuclear Governance, Economy and Ecology*.

Economies of scale help technologies to succeed, Ausubel points out. But there are no economies of scale with renewables. Just the opposite. More power from renewables means more land is used up. In fact the area needed for each kilowatt of power most likely increases.

This is because land that is good for wind, hydro-electricity, biomass or solar power would get used up first.

Looking at each renewable in turn paints a grim picture of their impact on the environment.

Take hydro-electricity. Suppose the entire province of Ontario, Canada were flooded with all the rain that falls on it in a year. Then store all this behind a 60 metre dam.

This would still generate just 80% of the energy produced by Canada's existing nuclear power stations. Put another way, each square kilometre of dammed land would provide electricity for just 12 Canadians.

Biomass energy is also horribly inefficient and destructive of nature. Vast areas would have to be harvested each year to produce power for a large part of the USA. To get the same electricity from biomass as from one nuclear power plant would take 2500 square kilometres of prime Iowa land.

"Increased use of biomass fuel in any form is criminal," says Ausubel. "Humans must spare land for nature. Every automobile would require a pasture of 1-2 hectares."

What about wind? A wind farm is three to ten times smaller than a biomass farm, Ausubel says. But 770 square kilometres of land are still needed to produce as much energy as one nuclear plant (generating 1000 megawatts electrical).

To supply the electricity the US used in 2005 would have taken a wind farm the size of Texas. This would have been covered with structures to extract, store and transport the energy. Even this is wildly optimistic, since it assumes round-the-clock wind at just the right speed.

One hundred square metres is a good size for a Manhattan apartment. But a far greater area would be needed to extract wind energy to run its laundry, microwave oven, plasma TV and computer. New York City would need every square metre of Connecticut turned into wind farms to power its electrical equipment.

Solar power is not the answer either. You could build a solar cell plant that would produce the same electricity as a 1000 megawatts nuclear power plant. But you'd have to paint 150 square kilometres of land black to do it. And you would need more land for storage and retrieval of the energy.

Every form of renewable energy needs vast infrastructure - concrete, steel, roads, Ausubel says. "As a Green, one of my credos is 'no new structures'. But renewables all involve ten times or more stuff per kilowatt as natural gas or nuclear."

The full footprint of uranium mining adds just a few hundred square kilometres.

There are certainly concerns about waste storage, safety and security. But the dense heart of the atom offers by far the smallest footprint of any energy source. Economies of scale would mean that the nuclear industry could increase the amount of energy it produces while shrinking the size of its power plants, Ausubel says.

This is what has happened in the computer industry. With investment and research, computers have grown steadily smaller and much more powerful.

"If we want to minimise new structures and the rape of nature, nuclear energy is the best option," says Ausubel.

"Renewables may be renewable, but they are not green."

*"Renewable and nuclear heresies", International Journal of Nuclear Governance, Economy and Ecology, Vol. 1, No. 3, 2007 229-243.

More help with words





fossil fuels



nuclear reactor





What's it all about?

  1. The first paragraph mentions three kinds of renewable energy. Name two of them.
  2. What will happen if we use any of these sources of renewable energy to supply all the energy the world needs?
  3. What kind of science is this story talking about? Did Ausubel do an experiment, or do a calculation or do something else?
  4. Ausubel compared the effects of using renewable energy to produce electricity with another way of producing electricity. What is that other way?
  5. "Watts per square meter" is the kind of shorthand that scientists use. Square meters are a way of measuring ----.
  6. Watts are a way of measuring power. So "watts per square meter" tells you the ----- produced by different power stations for the same area of land used up.
  7. The phrase "astronomical advantages" means that nuclear power stations produce much power in the form of ----------- than renewables.
  8. There is another way of looking at this. A power station that uses solar energy , biomass or wind turbines to produce electricity takes up an enormous amount of ----.
  9. The story gives examples taken from Ausubel's research on how much land you have to use up to get useful energy from renewables. It talks first about ----- -----------.
  10. Suppose we shut down all 25 of Canada's nuclear power stations. Then try to replace them with hydro-electric power stations. Ausubel shows that you need a dam much bigger than the whole province of ------- to do this.
  11. Ausubel looks next at -------.
  12. He says we would need to use the trees or plants from ---- square kilometers of "prime Iowa land" to get the same energy as from one nuclear power station
  13. What do you think this prime land is used for now?
  14. Wind power uses up less land than biomass but far more than nuclear. What would you have to do to Texas to produce enough electricity from the wind for the whole USA?
  15. Is solar power any better?
  16. Besides the power stations themselves, renewables also need new roads, buildings, cables and storage systems. What one word does the writer use for all of this?
  17. There are concerns about nuclear energy. State two of them.
  18. People who study how things are made and sold often talk about economies of scale. This means that the more of something you make the ------- it is to make each one.
  19. You get economies of scale with nuclear energy Ausubel says. But you don't get them with renewable energy. In one sentence and your own words explain why that is.
  20. What is the main conclusion of Ausubel's work?
  21. Imagine you are a scientist. Think up one question you would like to have answered about all this.
  22. How would you go about answering that question?

More teaching resources for this story

Renewables fail UK US

Topic for discussion, research or pupil presentations

The science in this story is simple – if you're a scientist. Young people still at school have a lot of misconceptions about energy and power, which is not surprising since it took scientists themselves many centuries to get it right.

Research shows that children often believe energy is intimately linked with being alive; they confuse energy with force; they see it as a type of fuel or a kind of fluid. These different misconceptions can often be held by the same person in different situations.

To try to make things clearer to young people in school, "more time should be devoted to qualitative questions", according to researcher Reinders Duit*, and "students should be advised to explain the physical phenomena in their own words".

This story provides a good opportunity to do precisely that. Working in groups students should tackle any or all of the following questions, some of which require research.

1 Fuel can be used up but energy can't. Explain this.

2 Imagine a power cut that lasts a whole day. Make a list of the things you do each day that you could no longer do. What if the power cut lasted a week, a month, a year?

3 Do the What kind of science news? exercises above. These are likely to generate even more debate and discussion than usual.

4 Using the results from these exercises try to answer the following questions: 1) What science has Ausubel actually done? 2) Are there any new discoveries in the story? 3) So what kind of story is this?

5 Make a list of the steps (no more than half a dozen for each) in getting electricity from wind, dammed water, biomass and solar cells. Then do the same for nuclear. In what way are solar cells different to all the others?

6 Confusion about concepts is not helped by the use of many different units for energy and power. These include joules and calories, and for electricity a set of units that sounds like they should be power but are actually energy – kilowatt-hours and megawatt-hours. There is also the fact that the calorie in everyday use is a perfectly respectable unit of energy but not the same one physicists use. It's a thousand times as large, and physicists call it the kilocalorie.

Working in groups, students should create as many examples as they can that illustrate joules (lifting an apple a metre in the air, dropping a bag of sugar), kilocalories (heating a kilogram of water, converting chocolate to motion) and kilowatt-hours. They should then attempt to create some way of picturing the amount of energy that the US used in 2005. That figure, according to Ausubel, was 4 million megawatt-hours – which is a whole lot of chocolate bars.

7 In the paper itself Ausubel describes himself as a Green, and goes on to say: "I should mention that I am not naïve about nuclear. Privileged to work with Soviet colleagues who participated in the Chernobyl clean-up, I saw the Dead Zone in 1990 with my own eyes. I visited the concrete sarcophagus encasing the blasted reactor …".

In one sentence students should answer this question: What is a Green?

*Duit, R. (1983) Energy conceptions held by students and consequences for science teaching In: Helm, H. and Novak, J.D. (eds). Proceedings of the International Seminar: Misconceptions in Science and Mathematics, 20-22 June 1983, Cornell University, Ithaca, N.Y. pp 316-323

Tips for science class discussions and groupwork

No 56

The connection between science and literacy is the subject of much attention in the science education community. This attention comes in large part from three sources. One is the growing body of research in science teaching and learning that suggests that language is essential for effective science learning – for clarity of thought, description, discussion and argument, as well as for recording and presentation of results. In addition to engaging in direct investigation of scientific phenomena, students make meaning by writing science, talking science and reading science. At the root of deep understanding of science concepts and scientific processes is the ability to

Extract from Douglas, R. (ed.) et al. (2006) Linking Science & Literacy in the K-9 Classroom. Arlington: NSTA Press.


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