Thursday, May 13, 2010

Robert Bryce on The Physics of Energy

The author of Power Hungry, the Myths of Green Energy and the Real Fuels of the Future recently published a piece in Forbes on the physics of energy -- specifically the power density of different energy approaches.
.... let's consider the power density of wind energy, which is about 1.2 W/m2, and solar photovoltaic, which can produce about 6.7 W/m2. [Wind and solar] are incurably intermittent, which makes them of marginal value in a world that demands always-available power. Nor can they compare to the power density of sources like natural gas, oil and nuclear. For instance, a marginal natural gas well, producing 60,000 cubic feet per day, has a power density of about 28 W/m2. An oil well, producing 10 barrels per day, has a power density of about 27 W/m2. Meanwhile, a nuclear power plant like the South Texas Project--even if you include the entire 19 square-mile tract upon which the project is sited--produces about 56 W/m2.

Simple math shows that a marginal gas or oil well has a power density at least 22 times that of a wind turbine while a nuclear power plant has a power density that is more than 8 times that of a solar photovoltaic facility. Those numbers explain why power density matters so much: if you start with a source that has low power density, you have to compensate for that low density by utilizing more resources such as land, steel, and ultra-long transmission lines. Those additional inputs then reduce the project's economic viability and its ability to scale.

That can be understood by comparing the land use needs of a nuclear plant with those of a wind energy project or a corn ethanol operation. The two reactors at the South Texas Project produce 2,700 megawatts of power. The plant covers about 19 square miles, an area slightly smaller than the island of Manhattan. To match that output using wind energy, you'd need a land area nearly the size of Rhode Island. Matching that power output with corn ethanol would require intensive farming on more than 21,000 square miles, an area nearly the size of West Virginia.

Environmental groups and many politicians in Washington insist that the U.S. must lead the effort to develop renewable energy sources, with wind, solar and biomass being the lead components. But doing so will mean replacing high-power-density sources that are reliable and low cost with low-power-density sources that are highly variable and high cost. _Forbes

Low power density is a strike against wind, but the intermittency and unpredictability of wind power is a devastating drawback of that approach to big power. The tendency for expensive wind turbines to break down and require extravagantly expensive maintenance and replacement parts, is a killer. The need for pricey natural gas turbine backup for wind power should make any serious investor alarmed over wind's long term prospects.

Of course, the Obama Pelosi regime loves wind energy, and will pay investors to install huge wind farms -- even if they never generate power! This is the government that is shutting down US coal, offshore and arctic oil, and oil shale projects. This is the government threatening to shut down importation of oil from Canadian oil sands, and threatening to shut down US unconventional natural gas resources on trumped-up faux environmental concerns. This is the government that takes a "go-slow" approach to new nuclear power designs and projects, to placate its fringe dieoff.left core political base.

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Blogger Unknown said...

Robert Bryce's remarks about relative energy densities are totally correct. All other things being equal, nuclear energy sources of any kind have intrinsic energy densities that are orders-of-magnitude higher than any chemical energies (on paper, by at least a factor of a million) and vastly higher system-level energy densities than intermittent, alternative power generation technologies that harvest either: photons from the sun (photovoltaic systems whose maximum achievable energy densities are intrinsically limited by the solar radiation flux impinging on their 'collectors'); or, kinetic energy contained in the earth's atmospheric winds (which are intrinsically limited by maximum earthly wind speeds and maximum speeds that can tolerated/harvested by currently practical wind turbine technologies).

On the subject of alternative nuclear energy, readers may be interested to know that there is a little-known budding new technology called low energy nuclear reactions (LENRs) that represents a truly safe, 'green,' paradigm-changing departure from today's fission and fusion technologies. Specifically, LENRs offer the possibility of potentially developing orders-of-magnitude less expensive, safe, truly 'green' portable distributed power generation systems that release CO2-free nuclear binding energy at costs vastly lower than today's uranium fission or even future hoped-for fusion reactors.

Low energy nuclear reactions are truly a 'green' nuclear energy source: no emissions of deadly gamma radiation or dangerous energetic neutrons, and no production of environmentally hazardous, long-lived radioactive wastes. Unlike fission processes, it uses hydrogen and inexpensive stable elements for 'fuel.' LENRs are not well known; there is presently little or no public coverage of them in the media, scientific press, or in the majority of 'premier' scientific journals.

Present commercial U-235 fission reactors and future D-T fusion reactors are based on what physicists call the 'strong interaction.' Unlike fission and fusion, LENRs primarily involve the 'weak interaction' --- they produce stable, nonpolluting transmutation products (i.e., new elements) and release clean, carbon-free nuclear binding energy in the form of infrared heat. Importantly, LENRs are not 'weak' energetically --- some of them can actually release more nuclear energy than D-T fusion reactions at comparatively modest temperatures and pressures. LENRs are fundamentally different from fusion and heavy element fission processes. Interestingly, some LENR laboratory devices have occasionally produced net heat fluxes higher than those typically generated in the fuel rods of commercial light-water fission reactors.

Given an absence of radiation shielding requirements and nuclear waste cleanup issues, LENRs could be enormously less expensive than existing fission and future hoped-for fusion power generation technologies. Unlike fission, LENRs' unique 'green' attributes should allow them to scale downward. That key characteristic may enable development of energy-dense, long lived, cost-effective systems that scale from small, battery-like devices, to distributed home heating and power generation units, mobile vehicular power sources, up to stationary Megawatt-class power plants.

Interested readers may enjoy perusing an excerpt from a nontechnical Lattice White Paper recently uploaded to the public website in the form of an MS-Word file titled, “Commercializing low energy nuclear reactions (LENRs): cutting energy's Gordian knot - a Grand Challenge for science and energy.” It can be found on SlideShare at the following source URL (live hyperlink) =

9:16 AM  

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