Two days ago I began a series that critically looks into Amory Lovins’ and the Rocky Mountain Institute’s latest paper against nuclear energy. Today’s post discusses the claim that small plants (termed “micropower”) are turning in a “stunning performance” and are the way to go. There are two parts to this post: exposing the flaws in their “micropower” data and discussing the differences of big plants and small plants.
Does RMI’s data fit their definition?
From RMI’s condensed version:
Despite their small individual size, micropower generators and electrical savings are already adding up to huge totals.After reading and researching RMI’s data, it is still unclear to me what size power plants RMI counts as “micropower.” Here’s RMI’s definition on page 11 (pdf):
1. onsite generation of electricity (at the customer, not at a remote utility plant)—usually cogeneration of electricity plus recovered waste heat (outside the U.S. this is usually called CHP—combined-heat-and-power): this is about half gas-fired, and saves at least half the carbon and much of the cost of the separate power plants and boilers it displaces;So I’m assuming that the size of “micropower” plants is 10 MW or less. The only problem with this is that the data and sources RMI uses do not tell you the size of the plants. According to the data from the 2005 WADE Survey (pdf) that RMI uses, there are about 300 GW of decentralized capacity in the world. The WADE Survey does not mention the average size of the plants included in their data. So basically we don’t know if the data includes all large plants, all small plants, or a mix. If RMI’s original source doesn’t tell us, how can RMI claim that the data is “micropower”?
2. distributed renewables—all renewable power sources except big hydro plants, which are defined here as dams larger than 10 megawatts (MW).
According to data from Ventyx/Global Energy Decisions (NEI subscribes to their large energy database), the size of the average co-generating power plant in the U.S. is 54 MW. There are a total of 80 GW of co-generating capacity operating in the U.S. (same number reported in WADE’s 2005 Survey on page 27). Of the 80 GW, only 3 GW are less than 10 MW in capacity. Based on just the U.S. data, the majority of the co-generating plants don’t meet the size criteria of “micropower.”
Distributed (decentralized) renewables are the other half of the definition of “micropower.” The problem is that RMI’s data includes centralized renewables. RMI’s Excel spreadsheet shows that the world added 11,471 MW of wind capacity in 2005. According to page 35 of the 2006 WADE Survey (pdf), only 5 percent of this wind capacity is distributed:
On-site wind systems: according to the Global Wind Energy Council, 11,769 MW of wind capacity was installed around the world in 2005. WADE has assumed that about 5% of this is DE [decentralized energy] based, translating into 0.93 TWh based on an 18% load factor.It seems RMI’s own data doesn’t meet its definition.
One more point. If “micropower” is supposedly turning in a “stunning performance,” then it is clearly not happening in the U.S. The chart below shows how much and what type of power plant capacities have been added in the U.S. since 1950. The chart also shows the average plant size built each year.
If “micropower” is recently turning in a “stunning performance,” then the average new plant size shouldn’t be as high as it is. The average plant size for the U.S. should at least be down in the 20-40 MW range, but it isn’t. The two times the U.S. has built a substantial amount of capacity during a short period of time also saw a scale up in the average plant size being built. RMI could argue that the rest of the world is flourishing with “micropower,” but their data so far hasn’t shown it.
The Virtue of Big Plants
From RMI’s condensed version:
Indeed, over decades, negawatts and micropower can shoulder the entire burden of powering the economy.The keywords are “can shoulder” a big economy. It doesn’t mean the economy should be run by small plants. The fact is that big plants yield greater efficiencies and economies of scale than small plants. From page 59 in The Bottomless Well:
Bigger systems are easier to keep hot because they have less surface per unit of volume, and because they can be surrounded by materials like concrete and steel that can both contain and survive the heat. There is, of course, much more than that to engineering efficient power plants. But first and foremost, the rule is simple: bigger can be hotter, and hotter is more efficient. So, decade by decade through the first century of electricity, power plants grew bigger, and in so doing grew more efficient.Amory Lovins and RMI proclaim the benefits of efficiency all the time. What is perplexing is why they would be against bigger plants considering bigger plants are more efficient than smaller plants.
Here are the numbers. According to data from Ventyx/Global Energy Decisions, of all U.S. cogeneration gas plants, those smaller than 100 MW have the lowest thermal efficiencies. Their average heat rate is about 11,600 Btus/kWh and their average thermal efficiency is 30.1 percent. Nearly one-quarter of the U.S.’ gas plants are 100 MW or less and their average thermal efficiency is 29.3 percent (includes cogen and non-cogen plants). Thermal efficiencies dramatically improve for gas plants greater than 200 MW.
Nuclear plants average a 10,400 Btu/kWh heat rate which calculates into a 32.7 percent thermal efficiency. Newer and bigger nuclear plants are expected to operate at greater thermal efficiencies nearly matching today’s combined cycle power plants. Mitsubishi’s 1,700 MW Advanced Pressurized Water Reactor is designed to achieve a thermal efficiency of 39 percent. Westinghouse’s AP1000 is designed for a 35.1 percent thermal efficiency. GE’s ESBWR is designed for a 34.7 percent thermal efficiency. And AREVA’s EPR is designed for a 36-37 percent thermal efficiency depending on site conditions.
Small, quickly built units are faster to deploy for a given total effect than a few big, slowly built units.Well of course smaller plants can be built faster than larger plants. But how small are we talking about and is it practical?
As stated above, small supposedly means 10 MW or less. A new nuclear plant ranges from 1,100 MW to 1,700 MW. If we need 1,100 MW to meet demand, is it practical to build 110 small plants or just one big plant? If 1,110 MW was all that was needed, one could argue 110 small plants are practical. But 1,110 MW is not all that’s needed.
According to EIA’s Annual Energy Outlook 2008, the U.S. needs to build another 260,000 MW of capacity by 2030 to meet growing demand. It’s not practical to meet that demand by building 26,000 small plants when we can build 260 large plants - especially since larger plants yield greater efficiencies in the first place.
Now this isn’t to say small plants aren’t worthwhile to build. The size of the plants needed depends largely on the market demands. But when a country operates about one million megawatts of capacity like the U.S., a lot of small plants simply are impractical to build. Especially when one large plant like a nuclear plant is small compared to the overall market it serves.
If economies of scale and greater efficiencies do not exist with bigger machines, then the wind industry would still be building kilowatt wind turbines instead of megawatt wind turbines. Contrary to what RMI believes, there is no one-size fits all solution.