Rob,
I sense your frustration, and agree on some points, but don't accept your premise fully. Water technologies are quite predictable, particularly tides, waves and ocean and river currents. Most photovoltaics (PV) is measured by watts per square meter at noon. So I agree with your point that energy should be measured as an actual output not as a nameplate. Actually this holds true in conventional energy generation as well — most generators do not live up to their nameplate predictions.
But while wind and solar are intermittent, it is rather blown out of proportion (pun intended). Solar radiation for the concentrated solar plants in the southwest are quite predictable, and the Solar One 64-MW concentrated solar plant, for instance, has been operational everyday since the generation facility came on line mid-2007. As for PV in non-desert settings, even on the cloudiest days I am generating a third of the electric "nameplate," so if I finance the system incorporating for that lowered output for a third of the year, then any extra power is 'gravy.' Sunlight is not as unpredictable as one might expect.
Wind always is tarred with this unpredictability label as well.
According to the recent article, Less Backup for Wind Power May Be Required, "The varying nature of wind power means that it is harder to forecast than the fluctuations in electricity demand. Adding large quantities of wind power to power systems is therefore challenging. The results of a recent study coordinated by VTT Technical Research Centre of Finland, an international collaboration within the International Energy Agency (IEA) has been published in a report entitled: Design and Operation of Power Systems with Large Amounts of Wind Power." The report contains a summary of the wind power impact assessments performed in 11 countries, with assessments divided into three categories:
Additional costs arising from the balancing of wind power fluctuations.
Grid reinforcement needs due to wind power.
Capacity of wind power to replace other power plant capacity.
The bottom line of the study, "With wind power penetrations amounting to 10-20% of the gross electricity demand, the additional costs (per MWh of wind power) arising from the balancing of wind power fluctuations are estimated to range between 1-4 €/Mwh (US $1.46-$5.88/MWh). This is less than 10% of the long-term market value of electricity."
Ken Westrick, CEO and cofounder of 3Tier, tracks solar, wind and hydropower future capacity and performance for electric utilities. He says, "While it is true that wind is intermittent it doesn't mean it is unpredictable, nor that it is unreliable. With regard to unpredictability, even several days in advance energy forecasts that are much better than climatology or persistence are available with a state-of-the-art forecasting system. Errors of less than 20 percent of nameplate capacity can be achieved regularly and with multiple wind farms that are geographically dispersed, the grid impacts become even less of an issue. Regarding reliability, when averaged over a year a wind project is quite reliable with regard to capacity, with average annual capacity factors within 10 percent of a long term average, which is much better than many hydropower systems."
In the January 4, 2008 RE Access article, "Keeping the Electrons Flowing" by John Dunlop, "In spite of that complexity, the wind turbine must perform those functions day in and day out. A wind turbine commonly is producing electricity up to 80% or 90% of the time." And further emphasizing performance, he goes on to state, "An owner receives no tax credit from the federal government until the turbine begins to operate, and then it only receives the credit based on the quantity of electricity produced — over a long period of time. Financial institutions, insurers, and project owners now depend on a continued flow of electrons from the wind turbine to justify their investments, which ultimately provide a reliable supply of electricity to power-hungry customers."
Economics of all energy systems are based on MWh outputs (electricity generated by hours per year) — not nameplate capacity of the system. This is true for traditional thermal systems (coal, natural gas, nuclear, diesel) which have heat losses, more moving parts, and greater O&M downtimes that have to be cataloged, tracked, and incorporated. That's what project financing due diligence is all about — pretty well sophisticated — and so far I haven't heard much complaints from end-users using established technologies in mature projects.
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<i>Nanosolar's founder and chief executive, Martin Roscheisen, claims to be the first solar panel manufacturer to be able to profitably sell solar panels for less than $1 a watt. That is the price at which solar energy becomes less expensive than coal.</i>
It is true that if you could build a PV plant for $1/W, the plant would be cheaper than a coal plant of the same rated capacity. However, the PV plant will typically produce less than one third the energy in KWH in a year than the coal plant, and the cost of the electricity in cents/KWH will be significantly higher for the PV plant than for the coal plant. This is the frustration.
-Carolyn L,
proud rooftop PV owner