by John Grady
 

Finding alternatives to fossil fuel-generated electricity is critical to the long-term viability of civilization as we know it. Two facts are only weakly disputed: (1) we will eventually run out of fossil fuels, and (2) burning them has detrimental effects on the environment. To be sure, there are technologies to pursue that extend the economic life of fossil fuel extraction and to reduce or isolate carbon emissions, but they just postpone the inevitable. This is why development of alternatives is being subsidized. Unfortunately, neither wind nor solar generation can scale to replace the base generating capacity of today's oil-, coal-, and gas-fired carbon-emitting power plants that provide most of the base capacity of the grid.

The grid depends on power sources that can produce constant output. For the most part, the grid has no storage capacity. It can only redistribute power from its source to where it is needed. There is efficiency loss proportional to the distance between source and use. Adding variable sources like wind and solar does nothing to reduce the base capacity the grid requires, unless the intermittent source includes storage onsite with it to be able to deliver a constant input to the grid.

I have written previously about the variability of output from solar panels and the actual generating capacity that is needed to produce an average output (a factor of 6-8 more capacity). The fact that the cost of generating a kilowatt of electricity at noon from a solar panel may be approaching parity with the cost of generating that kilowatt from oil or coal becomes irrelevant when you realize that you need 6 to 8 times as much peak capacity to produce the same average output. Producing that output constantly requires storage, to save the electricity generated at noon and to deliver it when the sun goes down.

Using that 6-8 factor, the newly installed 220kW solar panels at Carlson Orchards is the equivalent of 27 to 36kW 24 hours a day, seven days a week. That is about the same as three carpenter-style 10kW generators, costing less than $2,000. Don't get me wrong—I admire Carlson. It's smart to take something good, essentially "money for free." With such a large subsidy, it's a no-brainer. We would otherwise say no to 30kW for $1 million.

On a dark and windless night, we'll continue to need every single fossil fuel plant, to meet the same loads as always when nothing comes from solar panels. Not a single fossil fuel plant goes away with panels. I am all for panels—I have them on my off-grid summer house (with battery storage for light at night, and a propane generator for when the batteries die)—but at best they are a 5 percent player at utility scale, due to no power available at night. And that factor of 6-8.

Want to get off the grid, and go solar yourself? If the average Harvard home needs about 2kW 24/7, you will need roughly 7 percent of Carlson's setup to get it, at a cost of about $70,000, for 15.4 kW peak capacity. Depending on how much storage capacity you want, you'll spend another $5,000 to $10,000 for batteries, and the inverter to convert to AC when you use it. Add a few thousand for a backup generator, and for something under $100,000 you will no longer be responsible for a share of the grid's carbon footprint, and you'll only be contributing yourself when that backup generator kicks on.

What does that look like? For 2 kW, install 77 3-by-5-foot 200-watt panels, mounted on your roof or on poles in your yard—230 linear feet, for one house, plus batteries. Cut it all in half, if you can live on 1 kW (720kWh/month, check your electric bill for your current usage)

So if promoting wind and solar alone won't get us off fossil fuel, does that mean there is no answer? Not at all. What we need, nationally and internationally, are energy policies that address the whole situation, not just generation alternatives.

Most of the generation alternatives are best done in remote locations (remote deserts for solar collection, off-shore wind farms). As already mentioned, utility-scale storage is needed, along with the ability to move the power great distances. Both technologies exist, but they are very capital intensive, and will require time to develop and implement.

Pumped hydro—where water is pumped uphill to reservoirs above the turbines during periods of low demand, and released to additional or the same turbines during peak demand—is already in use at utility scale in a few places. According to Wikipedia, this is the best proven technology that scales, but environmental concerns (people don't like having their placid fishing stream turned into a 1,000-acre holding tank) and development time and cost makes it hard to implement. Locations remote from population centers may be more viable, at the cost of increased transmission distance.

China has 50 of these multi-billion-dollar projects under construction or planned right now; we have none.

Transmission lines can be made more efficient by using higher conductivity and denser conductors, (thicker, more expensive wires), and operating at higher voltage. Most of our long-distance transmission lines are decades old; upgrading them will be expensive and take time.

Some of our existing fossil fuel plants could produce twice as much electricity by the process of co-generation. For example, a plant may burn natural gas to drive a gas turbine; the exhaust from the gas turbine is then used to run a steam boiler, with a second steam turbine, almost doubling the output for the same gas that would be burned anyway in a boiler right now. This doesn't get us off fossil fuel, but it does reduce the rate of consumption. However due to widespread misunderstanding, such large improvements are not considered green energy. It obviously is even better than green energy, for now.

What alternatives can eliminate dependency on fossil fuels? The only carbon-free answer beyond hydro is nuclear power, as alternative energy simply cannot scale large enough to get the 30,000 MW New England uses ... now. And as a point of information, 30,000 MW would require 90,000 Cape Wind-size 1 MW turbines with 30 percent wind time ... and 90,000 MW-rated input storage for it. If a mile apart, this would mean 300 miles square of solid windmills. Reality?

Cape Wind output is 120 MW, net average of about 400 windmills; we need 30,000 MW in New England. Cape Wind is .004 of it. Is Cape Wind worth doing, given the environmental impact? I say no. A co-generation upgrade of just one of the 50 available gas plants could yield 5 times the new production of Cape Wind.

Slough Road resident John Grady is founder and president of Grady Research. His research facility was constructed on the site of a defunct 1930s-era hydroelectric generating facility on the Nashua River that was originally constructed to power ice-making for Fort Devens. New turbines were installed and the generating plant was brought back to life, producing 250kW of clean power. Power not used by his facility is sold back to the grid.