The Ergosphere
Sunday, February 11, 2007

Two easy pieces

The difficult parts of the emerging renewable energy economy are the high-efficiency biomass converters and new energy storage.  (The biomass-to-electricity converter is a sine qua non for the Sustainability scheme.)  These are essential; without high efficiency the energy yield of biomass is too low to support a high standard of living, and without storage the use of intermittent supplies (such as wind and solar) becomes problematic.

At least, they looked difficult.  Turns out one might be on the way as a solution for other problems, and a big chunk of the other is already available for free.

Storage first.  Nature magazine reports an experiment in the Netherlands which will use cold-storage warehouses as massive demand-managed systems to balance the variability of wind power and the daily demand curve.  (More commentary here, and a short project description here).  During periods of power surplus, the warehouses' refrigeration systems will be run full-bore to chill them by up to 1°C; when power production lags demand, the warehouses will shut off their chillers and coast on their stored heat-absorption capabity.  The possibilities are claimed to be huge:

The net effect would be that the warehouses would act as as batteries — potentially storing 50,000 megawatt-hours of energy — and the food wouldn't melt.

Electricity is expensive to store, but many of the things we make from electricity are not.  I've been touting the possibilities of ice-storage systems for A/C for some time.  Here's an example of DSM which is already available for free — and even has the control systems built in to handle shorter (6 minute) interruptions for the sake of peak-demand management.

This example is a clue-by-four to use on denialists.  They've been saying it can't be done, so now we can point to this and say "Holland is doing it, you ignoramus."  (As far as I'm concerned, anyone denying a confirmable fact gets one free pass along with a hotlink to the information which proves them wrong.  After that, they're fair game for any epithet you like.)  Once the warehouse systems are out there, we can extend the concept as necessary to leverage the variable energy resources.  The population of the Netherlands is about 16.5 million.  The US has about 18 times as many people, and likely about 18 times as much refrigerated warehouse capacity.  If Holland has 50 GWH of energy-banking capability available, the US might already have on the order of 900 GWH.  That's about 2 hours of average US electric consumption.  We'd have to build out one huge amount of wind and solar power capacity to strain that.

Being able to store renewable energy is no good if you can't make it.  So I was very happy to receive a note from a reader telling me about the Gas Institute's solid-oxide fuel cell powered by gasified chicken litter.  The power density of the SOFC was reduced to about 40% of normal due to the low-BTU fuel gas, but it did not accumulate any damaging deposits such as carbon.  The SOFC's going to DOE for testing recently were priced in the $250-$300/kW range; if the same cells were used for converting gasified biomass and nothing can be done to raise the power level again (such as pressurizing the system), the SOFC portion's cost would increase to $625-$750/kW.  This figure seems quite reasonable.  After adding fuel preparation and a microturbine to provide forced-air feed and bottoming-cycle energy recovery (and assuming no increase in power density from pressurization), I guesstimate that the system might cost in the neighborhood of $1000/kW  This is about the per-kW cost of a Capstone microturbine.

Dr. Lau and company appear to have used chicken litter because it is a disposal problem in some areas.  What other energy-rich materials are a disposal problem?  Excess rice straw?  Check.  Excess corn stover?  If you don't have livestock to feed, check.  Forestry waste?  Check.  Municipal green waste?  Check.  Plastic waste, waste cooking grease, etc?  The list goes on and on.

Nobody's sent me a note about a crop waste-powered SOFC being used to generate the CO2 for an algae growth system to make liquid bio-fuels, but at the rate my speculations have been popping up in the news, it wouldn't surprise me if it happens any day now.  It really does move too fast to keep up.

We look to be on-track for a Viridian green future, too late for comfort but sooner than anyone expects.

I hope that if this is your last post at Blogger, it will not be your last Ergosphere post. Be sure to give us a heads up if you move to a new host.
I'm looking at signing up with Typepad, and some of what I have in the pipeline would be good material for The Oil Drum (where I am an associate editor for the moment).

Much as some would like it to happen, you have not heard the last of me. ;-)
I was thinking that there could also be a design change to traditional home refrigerators to work in a similar way (making ice during times of surplus power to keep the unit cool during other times). This could, along with PHEVs (I read somewhere that 20k PHEVs could do the load leveling for California) and the warehouses could provide a ton of buffering/storage.

Also, there is a company out there called Ice Energy that makes an ice accumulator (makes ice at night when it is cool) to allow HVAC systems to run during the day much more efficiently.
Make sure you let us know where you move to! I for one don't want to be rid of you and your innovative ideas just yet...
TES Thermal storgae solves many problems

Even without the environmental issues, economics demand no new power plants.

Consumers need help from local and state government to reduce the cost of electricity.

Demand and supply are the major components of the cost of electricity. If we lower peak demand, supply will increase and the cost of power will fall significantly.

The primary method available to reduce demand is to make ice when electricity is cheap. Melt the ice for air conditioning when electricity is expensive or in high demand. This is a simple alternative to spending billions building new coal fired electric power plants.

Thermal Energy Storage, TES systems have been in use since Carrier invented air conditioning. One of the original applications was to use a small inexpensive compressor to make ice all week long and then melt all that ice to cool the sanctuary for two hours on Sunday. A common TES system is using tank type water heaters (hot thermal storage) to avoid large instantaneous gas or electric water heaters.

So why don’t we find a TES air conditioner in every house and small business? The answer is also simple:
• Most electric rates are averaged so it is not less expensive to buy electricity when it should be cheap and it is not more expensive to buy electricity in high demand periods when the price should be exponentially higher.
• In very round numbers it costs thousands of dollars per kW (or ton of A/C) to fund the construction of electric generation plants, transmission and distribution (TD) infrastructure. There are no mechanisms to divert funds from coal fired generators to funding TES systems in your home or business. The current conservative estimate of avoided costs to build generation, transmission and distribution infrastructure is $1000. per kW per year. This adds up to more than $45,000. over the 15 year life of a 3 ton TES system.
Should we invest $45,000 in new coal generating plants or invest a fraction of that in your home TES system?

If the above economic rationalization isn’t enough to convince you, consider the following additional benefits on TES.
• Running your air conditioner at night to make ice for daytime use is much more efficient because the ambient outside temperature is much lower and you’re a/c unit operates more efficiently.
• Running the generating turbine at night is much more efficient for the same reason, lower nighttime temperatures.
• All power plants run more efficiently when they are fully loaded and demand is predictable.
• Transmission and distribution is more efficient at night.
A massive deployment of TES will postpone the need to build additional power plants for many years and lower the cost of power for consumers. We can land on the moon. Why can’t we make ice?
Texas, you are preaching to the choir here, but it's good to have you around.  Texas is a windy (and sunny) place; if even the easiest and cheapest measures were taken to use them appropriately, Texans could certainly save a huge amount of fossil fuel.

(I lived just north of Slaughter Lane in Austin for a year.)
The 50,000 MwH is for all of the EU, not just Belgium.
That's what I get for not double-checking what I read.
Another thing, if there are regions in the EU which pass on the hourly cost of electricity, then this energy banking is probably already going on. A good case for not shielding the customer from peak electricity costs. It gives them vast incentives to do stuff like this.


Will it be scalable?

Where are you going to get the calcium?

Where are you going to put all that calcium carbonate?

This tech might best be used to seperate CO2 cheaply for sequestration underground (as CO2), without the need to trap it in the form of a heavy carbonate.
I guess one thing that the aove link might be good for is CO2 capture at night for feeding into the algal farms during the day...
The simpler way to do that might be to just make the algae farms voluminous enough to contain the overnight carbon emissions.  This costs in real estate but not energy.
There's no reason this concept couldn't be adapted to home refrigerators, air conditioners and heat pumps. All you need is a smart meter with time-of-day pricing, and a programmable thermostat on your appliance (refrigerator, air conditioner or heat pump).

Set the programmable thermostat to a lower temperature during times of cheap electricity (or higher, for a heat pump), and shift all your demand to the cheap period!
interesting idea, especially if can be applied to the millions of fridges. However all these conservation idea tick me off since most power production is less than 50% efficient to start with (nuclear was <30% last i heard.

Interesting appelation (Wheres the poetry?) Unusual combination of interests that I too appreciate.
I love the name Ergosphere - I immediately knew it was an energy blog, probably by an engineer! If you have moved your site please send me a new link. I am also and engineer with concerns about energy, especially in the developing world.
Most of my posts are going to The Oil Drum these days.
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