Being the developer of a low profile, high efficiency wind turbine and generator it pains me to have to dispel the myth that centralized renewable energy such as wind and wave reduces carbon emissions. Power produced in one location then transmitted via high voltage lines many miles then stepped down to the lower voltage distribution lines before delivery to the end user is centralized generation. Centralized generation relies upon the vast interconnection of transmission and distribution lines that crisscross the country known simply as the grid and herein lays the problem.

The grid network is sometimes referred to as the world’s largest machine and is divided into three parts, Eastern, Western and Texas. Power flows within each section as alternating current (AC) and must be synchronized at 60Hz while the connection between these three parts is direct current (DC). A drop of only 2Hz anywhere along the grid can rapidly heat up lines and trigger a chain reaction leading to massive outages like we witnessed in August 2003 along the east coast.

While it is correct that wind, wave and other renewable energy can save on CO2 emissions synchronizing demand and output to protect the grid comes at a heavy price. In a report by David White, Reduction in Carbon Dioxide Emissions: Estimating the Potential Contribution from Wind-Power, commissioned by the Renewable Energy Foundation, December 2004, White found that, “Fossil-fuelled capacity operating as reserve and backup is required to accompany wind generation and stabilize supplies to the consumer. That capacity is placed under particular strains when working in this supporting role because it is being used to balance a reasonably predictable but fluctuating demand with a variable and largely unpredictable output from wind turbines.

"Consequently, operating fossil capacity in this mode generates more CO2 per kWh generated than if operating normally.”

Six wave park applications have recently been made to the Federal Energy Regulatory Commission proposed along the Oregon coast. Each wave park is listed at 20 to 180MW output with ties to the mainland via 25kV transmission lines. Wave energy may be more predictable than wind energy but some wave buoy generators have a minimum and maximum swell they can operate in. Consequently, centralized wave energy will require fossil fuel powered generators to idle on standby and then cycle up rapidly to maintain grid integrity.

Sadly, electricity cannot reasonably be stored on an industrial scale. So how do we reap the benefits of carbon neutral power generation sources without relying upon a fossil fuel powered grid? The answer may lie in decentralized or distributed energy.

Distributed energy is power produced at or near the point of consumption. It is called distributed energy because this power is generated at the lower voltages carried by the distribution lines we see lining our roadways. Distributed generators can be gas powered or renewable like PV and small wind. All the synchronization problems associated with centralized power are significantly reduced or eliminated at the lower voltage distribution level.

Power generation at the neighborhood or district scale or just supplying individual homes and businesses is much easier to manage and surprisingly, is less expensive to the rate payer. Studies on wide scale deployment of distributed generation indicate as much as 44% reduction in capital costs versus centralized power and a 15% savings to the consumer in retail costs.

The transition from centralized to decentralized will not be easy despite a growing global movement toward wide scale distributed energy. One motivating factor toward decentralizing is the aging and deteriorating grid itself. While it is hard to find reliable estimates on the eventual cost of replacing and modernizing the grid, at a million dollars a mile and climbing, the number could be in the trillions.

Our electrical infrastructure has been ignored and the exorbitant cost of replacing the grid to maintain a costly centralized system makes transitioning to distributed energy almost inevitable. It is the cost to the planet in carbon emissions however, that makes it mandatory.


  1. Anonymous said...

    You have completely ignored two well known means of modulating system demand:

    1. Customers with non-critical or interruptible loads, such as off-peak water heating can allow their load to be aggregated with many other such customers in a region, and can allow their load(s) to be switched on or off in a complementary way to balance the fluctuations of an equivalent wattage of wind/wave/solarPV or other fluctuating renewable energy sources. Such balancing essentially makes the renewable generator and its complementary switchable load(s) "invisible" in terms of overall system demand;

    2. If I am a distribution company with a legal commercial arrangement with a renewable power generator, I can institute 24/7 Conservation Voltage Reduction (CVR) where I incrementally modulate the HV bus voltage at every zone-substation: I can modulate customer demand over about a +/-5% range whilst maintaining a safe and legal voltage to all customers' premises. Energy retailers naturally HATE this idea, because overall it means a slightly lower average voltage to most customers, and therefore REDUCED ENERGY SALES. One specific technical drawback is that during peak load conditions on any distribution HV/LV lines, the end-of-line customer is probably already at or very close to minimum safe voltage, so there is little scope for CVR to be safely applied.

    To regard "the grid" as being unique to the United States is far too parochial for a global medium such as the internet. Ohm's Law is also universally applicable, and its correct application to CVR proves that customer load is always influenced to a useful extent by habitual supply voltage settings.

    Michael Gunter

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