Archive for IGCC

Off topic: How Do the Candidates Stack up on Clean Energy?

A trip down to the local national party offices to participate in a press conference asking the presidential candidates to pledge their support for clean energy legislation got me thinking about the candidates… I wasn’t sure which candidate has the best clean energy platfom. So I spent a day reading thorough thier platforms, and came to a surprising (to me answer).2008 Election

You can read how I think the candidates’ platforms compare on clean energy here.

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MIT Study: IGCC may not be better for Carbon Sequestration

There’s a new study out from MIT which questions the received wisdom that IGCC or “Clean Coal” plants “will make it easier and cheaper to capture carbon dioxide, compared with collecting it from the smokestacks of conventional power plants.” The study calls for “large-scale demonstration programs that would, for the first time, capture carbon dioxide from coal plants, transport it, and store it at a large scale.”

While I disagree with the assertion that “coal… will continue to be a major source of electricity,” the reason I think that coal will not make the cut when the true costs of the associated emissions and environmental damage from mining are taken into account, the reason I believe this is that the costs of carbon capture and sequestration are likely to be much higher in reality than they are in theory, especially when we are attempting to sequester a “volume of compressed carbon dioxide … similar in scale to the amount of oil consumed in the United States,” and so we will no longer be able to use it only in places where it is actually useful, such as in enchanced oil recovery.

For this reason, I totally concur with the conclusion that we need to start doing large scale CO2 sequestration now, so we can decide if there is any hope of it working before we throw tons more money at cola plants (either conventional pulverized or IGCC) in the hope that some time in the future we’ll figure out some economic way to shove the carbon that we should have left underground in the first place back underground.

On the bright side, it looks like American Electric Power (NYSE: AEP) is trying large scale carbon capture and sequestration (CCS). I hope they can get it to work at reasonable cost… if CCS could be made to work cheaply, we could start capturing CO2 from biomass power plants, and have carbon-negative electricity.

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Visual Comparison of Electricity Generation Technologies

I just put together a couple graphs for a talk I’m giving on Monday to give people a visual feel of the various technologies for generating electricity.  These come with a gigantic caveat: the numbers are far from precise.

With changing technologies, it’s impossible to represent any of this with a single number anyway.  I’m trying to show how the technologies compare to each other, and I used four parameters:

  • Cost ($/MWh),
  • Availability (better the closer the profile of the technology matches a normal demand curve (wind is bad, baseload is okay, dispatchable is best, solar),
  • Emissions (and I count waste storage when it comes to nuclear),
  • Bubble sizes represent the size and durability of the resource (I’ve tried to combine in one number how much power we can get from the resource, but also how long supplies of fuel will last.) 

In both charts, the “best” technologies are in the upper left (low cost, low emissions, and available when we need them.)

I know that I’m going to upset a lot of people because I was too harsh with their favorite technology, so feel free and comment on the numbers I’m using, but also please provide references for where you get your numbers.  Most of these are off the top of my head, so their accuracy is admittedly questionable.   Here are the numbers I used to make the graphs.

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Seminar: Taking a Hard Look at IGCC. Denver Feb 12

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Secrets of the Utility Mind

I feel that many of us renewable energy activists do not understand how utility planners think.  To us, we see wind as cheap electricity, but to them it is the Predator (of movie fame), something that looks benign and friendly, but at any moment will wreak havoc on their grid by turning off unpredictably.

In order to have a constructive conversation with utility planners, I think it is important to understand their point of view.  This is my attempt to do that, with the hope by doing so, we will be able to engage with them more productively.

These are what I see as the underlying principles that shape the utility planning process:

There is no God but Reliability, and Least-Cost is his prophet.

Or, put another way,

The Holy Trinity of electric resource planning: The Baseload, The Cost, and the Holy Reliability.

I use the religious references to make a point: reliability is a religion for utility planners, and people become defensive and angry when you threaten their religion.   If we want to work with the utilities, we need to address their real concerns about intermittent renewable resources such as wind and solar.  And we have to work with utilities if we are going to modernize the way we get and use electricity. 

How do we deal with people committed to this religion?  By taking their concerns seriously, and helping them find solutions.   In short, when we hear “Wind is so unreliable,” we should say “That’s true.   Here are some ways we can take advantage of the benefits of wind without compromising the integrity of the grid.  We can be allies in getting regulators to approve rates that allow utilities to get a fair rate of return on these measures that improve reliability, while also allowing more wind onto the grid without impacting reliability.”

Why do we expect them to listen?  Because they already have and have to work to deal with a problem that is very similar to unpredictable generation from wind: unpredictable loads.  People and companies turn appliances and whole factories on and off unpredictably, and never once do they think about calling up the utility first to let them know that they should have the necessary capacity ready at the appropriate time.  Instead, we as consumers just flip a switch, and never expect that the lights won’t come on because there is not enough capacity.  If they don’t we get angry.

How do utilities accomplish this seemingly impossible feat of matching supply to capricious demand?  They do it with extensive load modelling, so that they can predict approximately how much  load will be on the system at any given time with a fair degree of accuracy, and by maintaining “Spinning reserves,” which are basically generators which are already up an running under very low power (hence “spinning”) and turning in synchronization with the current of the grid, like a non-hybrid car sitting at idle.

When there is a sudden increase in the necessary load, they can then increase the power produced from the spinning reserves almost instantaneously, like the motorist of our metaphor starting up when a light turns green.

There are many types of generation that can be used as spinning reserves, not only gas turbines.  Hydroelectric dams can work well this way, and can agreements with neighboring utilities to supply power when it is needed, on the theory that two different utilities will not have the same load patterns, and so both utilities can gain by trading power back and forth as needed.

There are many proposals circulating to increase grid reliability and ability to accept more intermittent resources.   As is usual in complex problems, there is no one solution, and in this case it will always be a combination of many of these (and some I don’t know about… please leave comments if you have ideas I’ve left out), and the mix will vary widely depending on the unique situation of any particular utility.

  1. More transmission.  Wind not only needs massive new transmission capacity to get the electricity from windy rural areas to the places that need power, but a more robust grid means that widely dispersed wind farms can all provide power to a single utility.  Since the weather varies in different places, this has the benefit of making the system as a whole a lot less variable.  Denmark sells power to Germany, Norway, and Sweden when their wind farms produce more power than they can use. 
  2. Moving to a national electricity system from the current system of regional grids would also ease the flow of wind power from one region to another.
  3. Time of Use/ time-based pricing.  Time of use pricing allows a utility to charge less or more for power depending on how much power is available at any given time.  Time of use pricing is currently a hodge-podge consisting of none at all for some utilities, and others that offer it (or even mandate it) for/to all customer classes.  Often time of use pricing simply consists of two prices: on- and off-peak, but the ideal goal for this is to actually have real time pricing, which will even depend on that day’s weather forecast (on windy days, electricity should be cheaper than otherwise.)  The ideal goal would be to eventually move all electricity customers to real-time or near real-time electricity pricing, so that customers who are willing to adjust their usage patterns are compensated for the service that they are providing to the system as a whole.
  4. Demand side management goes hand in hand with time of use pricing.  Demand side management involves giving customers incentives to keep their load from peaking too much at any one time.
  5. Dispatchable/Interruptible loads involve allowing the utility a certain amount of control over their customer’s energy use.  The classic example is installing a remote switch on an air conditioner, so that on a hot day, the utility can regulate it so that they don’t all come on a the same time, but rather take turns, lowering the peak demand on the grid.   Utilities typically pay their customers for this right for remote control.
  6. Large scale electricity storage: Pumped hydroelectric, flow batteries, hydrogen and stationary fuel cells, and compressed air energy storage are all ways to store large amounts of power when it is plentiful and cheap (on windy nights, for instance) until it is scarce and expensive (late afternoon and early evening.)
  7. Distributed energy storage, such as plug in hybrid or electric vehicles with vehicle to grid.  Vehicles which charge from the grid can be beneficial even if they are not capale of sending power back to the grid, simply because their owners can charge them only at non-peak times, a practice which is easy to incentivize with time of use pricing.
  8. New forms of generation that can serve as backup power.  Concentrating Solar with thermal storage, landfill gas turbines, and biomass gasification are all possibilities.  One often overlooked advantage of IGCC(“Clean Coal”) is that electric power from IGCC is generated by a gas turbine which burns the syngas product of the gasification step.  While it is quite possible that carbon capture and sequestration may never be made to work with IGCC, this is one reason (along with lower emissions of traditional pollutants and higher efficiency, which reduces carbon emissions for MWh generated) that renewable energy activists should prefer IGCC to old style pulverized coal plants.
  9. Increase energy efficiency, especially in appliances that are often used during peak times.  In most of the United States, peak load usually occurs on hot afternoons and evenings when air conditioners are running, so replacing an air conditioner with a more efficient one not only reduces overall energy use, it also reduced peak demand.  Once again, the institution of time of use pricing would give customers the incentive to upgrade the right appliances for energy efficiency first.   Here are two advances in efficient air conditioning I’m particularly excited about the Delphi HMX (formerly known as Coolerado), and thermally driven dessicant cooling.

For another well thought out perspective on energy storage, hop on over the the Ergosphere for the Engineer-Poet’s thoughts.

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Clean Coal?

Coal powered utilities have a “solution” to global warming caused by carbon dioxide, and they call it “Clean Coal” and “Carbon Sequestration.”  To many environmentalists, clean coal is simply an oxymoron.

 Also known by its technical name, Integrated Gasification Combined Cycle or IGCC, this new type of electric generator heats coal in the presence of oxygen, producing carbon dioxide and hydrogen gas, and leaving a bunch of the nasty stuff found in coal (mercury, sulfur, etc.) which would be released into the air in ordinary coal combustion plants stays (mostly) put.  The hydrogen is separated off by absorbing the carbon dioxide with an amine solution (other methods are in the works, but this is the only one in use now), and the hydrogen is burnt in a modified turbine to produce electricity.

Compared to conventional pulverized coal plants, this is an elegant solution.  There is much less of a problem with the traditional pollutants associated with coal (mercury, particulates, etc.), the whole process is slightly more efficient than pulverized coal, producing slightly more electricity per ton of coal burned (and carbon dioxide produced), and there is the theoretical possibility of capturing the carbon dioxide and putting it somewhere where it won’t enter the atmosphere and heat our planet (i.e. “sequester” it.)

On the downside, in the three IGCC plants currently in existence, there has been no attempt to capture CO2, for the simple reason that we don’t have any place good to put it, and any attempt to do so would require a significant portion of the energy output of the plant (I’ve heard numbers ranging from 10% to 30%), meaning that a lot more coal would have to be burnt just to deal with the carbon dioxide emissions.

FutureGen proposed design renderingXcel Energy, is with grants from the federal govenrment and other partners, is planning a 300 to 350 MW IGCC plant in Colorado, which will be the first in  the United States, as well as the first anywhere in the world to attempt carbon sequestration (most likely by taking some of the carbon dioxide and injecting it down old oil wells, a practicepioneered at the Wyburn oil field in Canada.  Some other methods of sequestering carbon dioxide, such as injecting it in brine formations, have shown the potential to form acid, leading to worries that the acid will breach the geologic formation, leading the carbon dioxide to escape.

In addition, according to an interesting article Can Coal be Clean? in the Nov 30 Economist, IGCC plants are also much higher maintenance than the old pulverized coal plants.  So is it any surprise that among the 150 new coal plants now being planned, only one or two are IGCC, and of those, only FutureGen is actually planning to test all the technologies that the utilities are holding up as the “solution” to carbon dioxide emissions, while the rest are just more business as usual.

Should we hold out much hope for IGCC with carbon sequestration?  Maybe in 30 years, after all the kinks have been worked out.  Carbon sequestration today is at a similar level of technological maturity as wind was in 1980.  Now that wind and solar have been generating electricity for 30 years, and are proven to work well, that’s where we should be focusing our efforts. 

I applaud FutureGen as a research project, but if we’re looking for a carbon neutral place to get our electricity today, IGCC with sequestration is a distraction.  However, if it can be made to work, I hope to be around when we have IGCC with carbon sequestration, fuelled by biomass, for a net carbon-negative power source.

Some numbers:

According to this testimony before the US house of Represnetatives, cost of electricity from IGCC without sequestration is $46 to $49 per MWh, and cost to sequester CO2 is estimated at $3-$10 a ton, depending on method an geology.  At treehugger, I found an article which implied that IGCC produces about 1 ton of CO2 per 5 MWh, which would make the cost of sequestration between $.60 and $2.00 per MWh, or .6 to 2 cents per kWh.   We do need to consider the fact that some of that $3-$10 per ton cost comes in the form of cost of electricity, so the calculation of cost of energy becomes depends on the source of electricity for sequestration, and how much of that carbon is sequestered.  None of this includes the cost of carbon capture, which would likely be low if only a fraction of the CO2 were captured, but become more expensive as the 90% or so theoretical limit is approached.  60% capture seems to be a number that the people who study this think would not be onerous in terms of cost.

 There is an incredible pile of information to sort through at Gasification.org.

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