Estimates of how far renewable energy sources could take us from the current fossil fuel paradigm are very good lately.
For example, a 2007 paper by PrimeStar Solar’s Ken Zweibel, Solar Energy Campaign Director James Mason, and Vasilis Fthenakissay, the head of Brookhaven National Laboratory’s Photovoltaic Environmental Research Center, indicate that we could get 69 percent of all the electricity needed in the United States from solar by 2050.
A newer paper, dated November of 2009 and authored by Mark Z. Jacobson, a Stanford professor, and Mark A. Delucchi, a UC Davis researcher, suggests that we could get 100 percent of our needs from renewables, and fully 40 percent of those from solar options like rooftop photovoltaic (PV) systems, PV power plants (in the 300 megawatt range) and concentrating solar (CSP) by 2030.
Ignoring the first – not because it’s less optimistic but simply because it’s older – I’d like to focus on the latter, which cites a cost of US$420 billion to remake the nation’s system of electricity transmission, distribution, substations and monitoring equipment.
It’s a huge cost. Even so, it is still less than the U.S. spends yearly on crop subsidies, and the bulk of it could be paid for through a cap-and-trade measure like Waxman-Markey (an energy bill which, as of September 2009 was still making its way through the Senate).
Additionally, the cost of creating this power supply via PV installations and wind turbines, and getting it to the end user, would still be less than the projected cost (per kilowatt hour) for future coal- and oil-burning plants and nuclear power stations.
For example, where renewable technologies are expected to deliver electricity at 4 cents per kilowatt hour (kWh) by 2020, conventional power (from fossil fuels) is likely to have increased from 2007 levels of 7 cents kWh to 8 cents by 2020, and the increases are largely attributable to existing or anticipated carbon regulations.
Costs aside, the first question that comes to mind is whether the nation’s (and the world’s) energy infrastructure could be rebuilt in two decades. According to Jacobson and Delucchi, that depends on the technologies chosen, the availability of raw materials used, and almost incalculable economic and political factors.
Fortunately, the authors have chosen to write their report based on renewable energy technologies extant today, rather than those that might become available in two or three decades. They have also focused on several key concepts, including the fact that the amount of land needed for solar and wind (for the projected 90,000 solar plants, and 3.8 million wind turbines) is less than might be expected.
The 3.8 million wind turbines, for example, could all be placed on less than 50 square kilometers (19.30 square miles, or 0.000032 of earth’s surface). This is an area smaller than Manhattan Island in New York City, and the actual land usage would result in taking up about one percent of the earth’s surface, with the area around the turbines devoted to farming or grazing.
The solar component (less rooftop PV, or residential applications) would comprise about 29 percent of the earth’s surface, broken down as 0.19 for CSP, and about 0.096 for commercial PV power plants – again, a nominal amount. However, where the space between turbines remains usable, the space between solar panels does not, and, as Jacobson observes: observes: “Solar spacing is about 1/4 that of wind, but the footprint on the ground is 6000 times higher.”
As high a figure as 29 percent seems to be, it is important to remember that about 33 percent of earth’s surface is either desert or desert-like, according to the New World Encyclopedia, and withdrawing it from agriculture or grazing would not have a significant effect on world food supplies.
In laying out his carbon-free energy calculation, Jacobson has also estimated the amount of power that will be required in the future. For example, in 2030, global demand will likely be about 16.9 terawatts (2.8 of that in the U.S.) – an amount will be reduced to 11.5 terawatts (or 1.8 in the U.S.) thanks to the fact that renewables imply their own conservation.
According to Jacobson, this savings would result in a 30 percent reduction across the board for all global power supplies.
“Our plan is to convert all energy to either electricity or hydrogen (where the hydrogen is produced from electrolysis, which also requires electricity). The efficiency improvement results primarily from the fact that electricity is more efficient than internal combustion.
A good example is with vehicles. Only 17-20% of the gasoline put in a tank results in moving a car; the rest of the energy in the gasoline is lost as waste heat (that directly heats the air and contributes to warming). Of the electricity plugged into a pure electric vehicle, 76-85% goes to moving the car and the rest is lost as waste heat. As such, converting to vehicles results in a vehicle efficiency improvement alone of a factor of 4-5.
Converting other processes to electricity also improves efficiency to different degrees. Converting to hydrogen has less benefit but still results in efficiency improvement over internal combustion. The efficiency improvements described account for most of the 30% overall reduction in energy needs.”
For Jacobson, a civil and environmental engineer, and Delucchi (a research scientist vested in sustainable vehicular systems), the “materials hurdle” may be the most intimidating. The rare materials needed to make solar PV arrays and batteries to store electricity include indium, lithium and platinum, the last of which is projected to supply only enough for 20 million (vehicle) fuel cells over the next 100 years or less.
The intermittency of solar and wind – also viewed as a reliability factor – is seen as less of an obstacle. As the report notes, both have less than two percent downtime (five percent for wind at sea), while the average U.S. coal plant is offline for servicing fully 12.5 percent of the time. Additionally, because wind commonly blows when sunshine is infrequent, and calm days produce solar energy when wind is absent, the mix is more or less stable on its own, without human intervention.
Another roadblock, and perhaps the most insurmountable, might be economics and politics. However, with extremely aggressive policies in place, Jacobson notes, all current fossil-fuel capacity could potentially be retired and replaced with what he calls WWS (wind, water and sun) by 2030, though more likely such replacement will take 40 to 50 years.
Or, as my father used to say: “Soonest begun, soonest done.”
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