John Turner’s Renewable Energy Future; renewable technologies compared.

When you want an informed, but unbiased opinion, it’s usually best to ask someone John A Turnerwhose livelihood does not depend on coming back with the “right” answer.  When it comes to comparing different renewable energy technologies, one of the best experts I’ve heard from is John Turner.   Dr. Turner is a principal scientist for the Center for Electric & Hydrogen Technologies & Systems at the National Renewable Energy Laboratory (NREL), in Golden, Colorado.

The Hydrogen economy is that long hoped for world in which one day our cars will fill up at the corner hydrogen station, and combine that fuel with oxygen in the air, a process which will create electricity for the car’s motor, and with the only emissions being water.  It all sounds wonderful, but to reach that nirvana of zero emissions, the hydrogen itself needs to be produced with non-emitting technology.  That is because, contrary to oversimplified hype from politicians, hydrogen is not an energy source, but rather an energy carrier.  Like a battery, it has to be produced (charged) before it can be used.

Dr. Turner’s goal is to guide us to the hydrogen economy with as few missteps as possible, with missteps in his mind being the used of unsustainable technologies to get there.  Since he wrote his visionary 1999 article in Science, outlining a path to a “Renewable Energy Future” in which hydrogen serves as portable energy storage for an economy fueled solely by renewable sources of power.  The weak link in this chain is fuel cell technology.  Fuel cells are used to efficiently convert hydrogen and oxygen to electricity and water.  They have been around for well over a century, but are still too expensive for use in cars, although they are practical in some military and larger scale civilian operations.  A similar problem exists for hydrogen storage.

In contrast, hydrogen as a storage medium for electricity from intermittent power sources such as wind is a technology whose time has come. Norsk Hydro is currently doing a trial run of a wind/hydrogen combination system on a small Norwegian island, powering 10 homes.

What is most interesting to me about his presentation, is his unbiased comparison of different renewable technologies, along with nuclear, and Internal Gasification Coal Combustion (IGCC) with carbon sequestration.

He compares these technologies for robustness: the ability to meet our future energy needs; for expense, and for Energy Payback.  Energy payback and the related measure EREOI (Energy Return on Energy Invested) give us an idea of how much of our energy will have to be devoted to making more energy.

Here’s the run-down (with some additions of my own):

Technology

Energy Payback/ EROEI Robust? Price per kWh (approximate 2003 prices) Long term?
Wind

3-4 months; 20-30x

Yes

5-8 cents

Yes

Solar PV

3-4 years; 8x

Very

21-24 cents

Yes

Concentrating Solar

5 months; 40x

Very

8 cents

Yes

Biomass

varies

No

7 cents

Yes

Geothermal

varies by source

No

4-7 cents

Yes

Nuclear

1 year, not counting waste disposal. <20x

Yes

13-18 cents

?

Coal (w/ carbon sequestration)

16% of energy required for sequestration.

For now

5-6 cents

70 yrs, at current growth rates.

Energy efficiency

months; 50x +

Can never get all energy from efficiency

1-2 cents

Yes

(Items with links are from linked sources)

We’ll need all these energy sources, but Wind and concentrating Solar (CSP) stand out as near-term, robust, economical solutions, while Energy Efficiency and Geothermal will give us the most bang for our buck as we try to get started down the road.

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