Orders of magnitude in energy systems

A solar photovoltaic system at the Ecovillage at Ithaca, where I live (www.ecovillage.ithaca.ny.us), consists of 14 households each with a PV system, for a total of 32 kW of rated capacity. These 14 arrays together produce about 30,000 kWh of electricity per year.

This amount is less than 1/100th of the electricity produced by one wind turbine with rated capacity of 1.5 MW at the Fenner wind farm near Syracuse, NY. Fenner’s 20 turbines produce between 80 and 90 million kWh per year.

The total output of Fenner is, however, only about one twentieth of the output of the AES Cayuga coal-fired power plant on Cayuga Lake, also near Syracuse (rated at 240 MW, with an annual output of roughly 1.5 billion kWh – my rough estimate).

Lastly, AES Cayuga has only about one fifth of the output of one of the three 1000 MW nuclear power plants located along the shores of Lake Ontario near Oswego, NY. Again using my rough estimate, each of these plants produces on the order of 7.5 billion kWh per year. There are approximately 100 nuclear power plants and 1000 fossil-fuel fired power plants in the U.S. So, from top to bottom, it takes on the order of 10,000 neighborhood-size PV systems to make as much electricity as one nuclear power plant.

I do not in any way intend this calculation as an argument against renewable energy. On the contrary, I am in favor of getting to 25% or 30% of our primary energy from renewables as quickly as we can. But I don’t think we should have any illusions: we will need to greatly accelerate the pace at which renewables are built and installed, and maintain this pace over many years or decades, if we want to see this milestone achieved in your or my lifetime.

High oil prices are no substitute for a comprehensive CO2 policy

Back in July of this year (2008) oil prices peaked on the world market at $147/barrel. It appeared that a new age of permanently high prices for oil, and eventually gas and coal as well, was at hand, which would allow renewable options to compete more effectively on the basis of price alone. Without any further intervention, the world would shift steadily away from CO2-emitting technology.

Now, in 4 months, they are back down below $54/barrel. Furthermore, with the tightening of credit, renewable energy systems that depend on capital investment to get off the ground are less financially attractive -- in the absence of policies such as cap-and-trade or a carbon tax -- and also less able to win financial backing. Everything is up in the air. On the one hand, the U.S. consumer, having seen how $4 per gallon gas can lead to a $100 fillup at gas stations, is wary of buying a large energy-intensive vehicle, for fear that high gas prices may return. On the other hand, the surge in renewable energy projects has been dealt a blow.

The whole experience points to the need for policies that deliberately and directly deal with phasing out CO2 emissions, rather than leaving it up to the price of fossil fuels. During the election, the last three candidates left standing -- Clinton, McCain, and Obama -- all talked about 60 to 80 percent reductions in CO2 by the year 2050. Whether it's cap-and-trade, a carbon tax, efficiency standards, or some other approach, we need to institute such policies starting very soon, and then stick with them through all the ups and downs in energy prices that are to come.