Renewable energy accounting

Could energy needs be met with renewables? Last week, a New York State feasibility study by Mark Jacobson and coauthors was released by the journal Energy Policy (pdf). In February 2011, when papers by Jacobson and Mark Delucchi examined global energy options, I took a look at their assumptions. Reprinted in full below.

Mark Jacobson (Civil and Environmental Engineering, Stanford) and Mark Delucchi (Institute of Transportation Studies, UC Davis) have authored a new pair of papers on meeting the world’s energy needs through renewable energy.

The two papers offer:

  • An accounting of renewable energy provision (largely with wind, water and solar) sufficient to meet to projected global energy (electricity, transportation and heating/cooling) demand in 2030;
  • An accounting of land use required in such a plan;
  • An accounting of material resources required (such as neodymium, lithium and platinum);
  • An accounting of current and projected annualized generation and transmission costs of the proposed WWS (wind, water, solar) system versus conventional electricity generation; and
  • A portfolio of strategies for overcoming challenges of intermittancy and distribution (the wind and sun don’t blow or shine everywhere at all times).

On that last point, here is their overview of strategies for matching supply to demand:

[T]here are at least seven ways to design and operate a WWS energy system so that it will reliably satisfy demand and not have a large amount of capacity that is rarely used:

(A) interconnect geographically dispersed naturally variable energy sources (e.g., wind, solar, wave, and tidal),

(B) use a non-variable energy source, such as hydroelectric power, to fill temporary gaps between demand and wind or solar generation,

(C) use ‘‘smart’’ demand-response management to shift flexible loads to better match the availability of WWS power,

(D) store electric power, at the site of generation, for later use,

(E) over-size WWS peak generation capacity to minimize the times when available WWS power is less than demand and to provide spare power to produce hydrogen for flexible transportation and heat uses,

(F) store electric power in electric-vehicle batteries, and

(G) forecast the weather to plan for energy supply needs better.

This piece describes their assumptions about how energy demands might be met:

We have assumed that all end uses that feasibly can be electrified use WWS power directly, and that the remaining end uses use WWS power indirectly in the form of electrolytic hydrogen (hydrogen produced by splitting water with WWS power). …

[W]e assume that most uses of fossil fuels for heating/cooling can be replaced by electric heat pumps, and that most uses of liquid fuels for transportation can be replaced by BEVs (battery-electric vehicles).

The remaining, non-electric uses can be supplied by hydrogen, which we assume would be compressed for use in fuel cells in remaining non-aviation transportation, liquefied and combusted in aviation, and combusted to provide heat directly in the industrial sector.

The hydrogen would be produced using WWS power to split water; thus, directly or indirectly, WWS powers the world.

The study follows and extends on the authors’ 2009 Scientific American cover story: “A Plan to Power 100 Percent of the Planet with Renewables.”

It is one of several large-scale accounting analyses that look at the viability of replacing current energy portfolios with renewables, or with renewables supplemented by other options, such as nuclear and natural gas. According to the authors, it is the only recent plan that is global, WWS-based, and addresses all demand sectors. In 2008, David MacKay published a widely praised energy accounting for the UK, “Without the Hot Air.”

Here is the lede paragraph of the press release, as published by ScienceDaily:

If someone told you there was a way you could save 2.5 million to 3 million lives a year and simultaneously halt global warming, reduce air and water pollution and develop secure, reliable energy sources – nearly all with existing technology and at costs comparable with what we spend on energy today — why wouldn’t you do it?

The papers, in pre-press at Energy Policy, are:

  • Providing all global energy with wind, water, and solar power, Part I: Technologies, energy resources, quantities and areas of infrastructure, and materials (pdf)
  • Providing all global energy with wind, water, and solar power, Part II: Reliability, system and transmission costs, and policies (pdf)

(See also: “Intermittency and the HVDC Supergrid“)

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