Automotive battery prices falling faster than expected

New reports (PDF) indicate (via GM-Volt) that the cost of lithium-ion batteries for automotive applications (like the Tesla Roadster, Chevy Volt and Nissan Leaf) are coming down faster than was previously expected. At a recent conference, A123 stated that they were negotiating contracts for automotive Li-Ion batteries for 2012 delivery at under $400/kWh, a reduction of almost 40% over 2009 prices ($650/kWh) in only 3 years. If the trend holds, a report published in-part by the National Academy of Sciences would be way off since it estimates the $400/kWh price point wont be hit until 2020, 8 years later.

Elon Musk (Tesla CEO) postulated a “weak Moore’s law” for Li-Ion batteries, that the price/performance ratio will increase by 8% per year, or 9 years to double. The price/performance ratio is the ratio between the price per kWh of the battery pack and the amount of energy the battery can store. If current batteries can store 140Wh/kg and cost $500/kWh, an 8% improvement means either the storage goes up to 150Wh/kg, the price goes down to $460/kWh, or somewhere in between (145Wh/kg and $480/kWh). A Tesla battery pack would go from $35,000 (53kWh at $650/kWh in 2009) to $24,000 ($400/kWh in 2014), a reduction of about 10% of the entire price of the car over approximately 5 years. Combined with other cost saving methods, the next stage of the Tesla evaluation – the Model S – starts to look feasible. Its still not going to be the most affordable car, however significant progress is being made.

The cost per battery pack can be broken into two parts – the batteries themselves and the pack. The pack costs can be trimmed considerably with mass-manufacturing. Instead of hand assembling each battery pack and set of battery modules (a series of cells), semi-automated assembly can increase the throughput of the teams assembling dramatically while keeping the same number of people around, reducing the amount of employee-hours spent per battery pack.

The cell costs don’t come down as easily. This is the decidedly slower part of the electrification of vehicles. Following the 8% rule, automotive battery packs due in 2009 cost approximately $650/kWh. In 2014 this cost is about $430, and by 2017, the cost is $330/kWh, and by 2020 $260/kWh. Following the more agressive price decreases noted above, prices in 2017 would be $235/kWh, and by 2020 $172/kWh.

So by 2020, a Volt-style battery would cost $4,200, or about the cost of a new engine (a rebuilt one can be had for less). This assumes that other battery performance parameters do not improve – rather the Volt still requires a 16kWh battery and only uses 8.8kWh of the battery pack. If the current estimates of what battery specifications will be by 2020 (2,500W/kg, 250Wh/kg, 2,000 cycles and 4,000 recharges at 70%DoD) the Volt would be able to have its pack size reduced to 12.5kWh (50kg, 110kW), thus reducing costs further to $3,250 for the battery pack, and the total price premium of the E-REV system would be approximately $5,500. Factoring that cost over 5 years is $1,100 per year in savings needed over gasoline, which is achievable when factoring in savings in electricity costs over gasoline (approximately 9c or 11c/mile savings depending on cost of electricity), reduced maintenance costs ($150/yr for oil changes, etc) and reduced variability of fuel costs – my electric company needs a regulatory body’s approval to change the price of energy, the local gas station chain can add 10 or 15c to the price of gas over a holiday weekend because they feel like sticking it to us.

By 2030, barring any new technology that would leapfrog Li-Ion on price and performance, battery prices would reach $110/kWh, and total costs would be equivalent to a Prius premium today.

Over the long term, E-REVs are workable from a consumer finance standpoint. Initially, subsidies, longer warranties and extended payback periods will be needed to entice the consumer to buy in to the electrification of vehicles. If we can manage to stick with it for the next 5-7 years, it will take off and the nation can start to wave good-bye to oil and petroleum for their in-city commutes, and we’ll all breathe easier with less smog.

TiVo Premiere (Series4) announced – good but not great

TiVo announced their new TiVo Premiere model today. The unit added a lot of what was needed to improve the TiVo experience and bring it into the 21st century, but not everything is in place. Is it enough to overcome being stymied by CableLabs and their slow progress?

The first thing to recognize is that TiVo fixed most of the major gripes with their existing units. Their biggest problem is the cable companies themselves vis-a-vis CableLabs, and while I’ll not address anything having to do with them for now (there is a long list of gripes), I had a long list of things TiVo needed to fix in a draft blog post ready to hit the “Publish” button had they messed up. Lucky for them I’m scrapping that post! (well, recycling it into this post, got to be green!)

Upgraded Hardware. While the device is still limited to two tuners (the Moxi supports three, new cable cards will support up to six), the upgraded Broadcom Chip on the inside is a dual core 400MHz MIPS processor and 512MB of RAM with clustered multi-threading (portions of the core like the execution unit are partitioned to support more than one thread per core). So once they manage to optimize their interface they should be able to take advantage of the hardware, even if the 400MHz speed look rather slow.

New HD Interface. The Series 3 TiVo uses the ancient SD interface, while the new Series 4 models use the new Adobe Flash-based UI. While the old interface is leaps and bounds above the standard cable set-top box (STB), other set top box makers (DirecTV, Dish, etc) are quickly catching up, and non-broadcast STBs like the Boxee Box already provide an experience that is better. TiVo should be the far and away leader given the head start they had, but they haven’t kept up. The new UI still needs some (a lot) of polish (“My Shows” should go back to “Now Playing” considering it can contain non-TV show content) but they seem to have got out of the rut they were in.

Better integration with internet content. Whether its the latest episode of The Big Bang Theory or a new Tekzilla I want them all in one list, organized by show name. I want one screen that shows me all the content I can watch now, whether its recorded TV shows, internet TV shows, plus TV shows, movies, pictures and music from my home network. Everything in one place. While I wont be able to get the stuff from my home network, I’m hoping the UI addresses the centralization issue.

Apps. The new TiVo is supposed to have an API available for developers. Combined with the Bluetooth Remote/Keyboard I can see cool Facebook or Twitter notifications. We’ll see if TiVo opens it up to all comers. If so, they are definitely going to need some sort of App Store. It would be really neat though, to replicate some of the iPhone App Store successes on the TiVo.

What did the get wrong?

No DLNA. I wont mince words, this is a huge mistake. TiVo’s proprietary protocols for sharing recorded content needed to be dropped a long time ago in place of the DLNA standard. Part of this might be restrictions imposed on them in terms of getting video out, but at the very least, I should be allowed to stream audio and video into the TiVo from my Windows Home Server easily, and it would be nice if they supported video formats like MKV (MP4+AC3 or DTS) since its really only a container around codecs supported by the Broadcom decoder chip.

No Built-in Bluetooth. While I can understand selling the awesome slider remote for $80, not including the $10 Bluetooth chip inside the unit seems incredibly weak. If I already have a BT keyboard I could do without one in my remote (especially for $80). Allowing BT keyboards in the first place was a great idea, but allow people who already have the hardware to use it! Also, BT would be useful for talking to a TiVo iPhone/Android application to use my phone as an advanced remote control, again, meaning that I don’t need the remote and BT dongle, rather just the BT capability.

While I still think TiVo needs to strengthen their engineering department to make their product better (DLNA, TTG Mac client, etc), the Series 4 is a step in the right direction. Hopefully they can manage to produce a new box more often than every 3 years to keep up with the rate of change in consumer electronics and can manage to squeeze more out of the Series 4 hardware they’re going to start shipping soon.

Finally, one parting thought on comparing a Tivo to an iPhone.

I think its odd that I have no problem dropping $300 every year on an new iPhone plus $30 a month for data and yet still complaining about AT&T’s poor service. But everyone is griping about the TiVo’s price ($300) and monthly costs ($13 or $400 lifetime) and yet they still love their TiVo. It is incredible to me actually. Why does everyone have such a hard time justifying to themselves a $300 TiVo once every three years and the $12.95/mo. I might get more out of an iPhone, but I would presume more people spend more time in front of the TV than a phone (except for teenagers perhaps). The only possible reason I can think of is because the only people I hate more than my cell phone provider is the cable company for its annual price increases. That and it would cost me an extra $10/mo just to them to add a Series 4 TiVo to my house – $2/mo cable card fee PLUS $8/mo for “additional digital service outlet” which is a, pardon my language, bullshit charge hoisted on us by the cable companies and the hardware vendors.

The 2010 Decade – Removing the PC from the Internet equation

By the end of the decade, connected devices will outnumber computers and smartphones on the internet. From monitoring devices like smart meters for the power grid, wireless picture frames, cars and their navigation systems, and even more things that haven’t been invented yet. We might laugh at the Tweeting Scale, but its these types of devices that will dominate our future.

Essentially, the internet goes from something you sit down at a computer to use to something that connects everything in our daily life together.

Brief Thoughts on Nissan Leaf EV

So Nissan announced their EV for commuters – the LEAF EV. 100 miles (spec.) on electricity. So what makes this stand out over all the other EVs being offered or promised?

First, the most interesting thing I saw was the 50kW DC charger. This is incredibly useful from a commuter standpoint – if you’re on your way home from work and need to run some errands, if you plug it in for 10 minutes you get an extra 30 miles, which will probably get you anywhere you need to go in your city.

Next is the that the electric motor is capable of 80kW (106hp). That is low compared to the Volt’s electric motor is 111kW/150HP, and the LEAF is estimated to weigh about the same (3,300-3,500lbs) as the Volt – as the extra 8kWh of batteries are about the same weight of the Volt generator. I’ll be interested to see acceleration and highway performance of the LEAF once they start to do road tests.

Overall, I don’t think they’ll hit their 100 mile range target, even the current Mini-E owners are saying that their real world mileage is about 70 miles per charge despite promises of 100 mile range. Not that 70 miles is bad, but there might be the occasional time where something happens and you end up exceeding 70 miles in a day. This is why its imperative that the same working group that did the SAE J1772 connector start work on a high capacity off-board DC charger. Up to 50kW is probably enough, assuming the 20-30 miles per 10 minutes figure holds up. Not all batteries will be able to handle that (E-REVs and plug-in hybrids wont be able to charge that quick) but if they could dial it down to what they could accept (15kW, 6kW, etc) it would allow more “charge point” and “service station” type places to recharge your electric car.

GM Promises Full 40 Mile Range at the End of 10 Years

In a recent online chat, when asked by a member of the public, GM stated that the Volt will have its full 40 mile range for the warranty period of the battery (10 yrs/150,000 miles). How will they manage that?

The Volt’s battery is 16kWh, with 50% of the capacity (8kWh) used to propel the Volt the first 40 miles. So how does GM guarantee that it’ll last that 40 miles for the full life of the vehicle? Well, as the total capacity decreases, the Volt can still pull 8kWh of energy from the battery. There are a few issues with this approach however.

First is that the maximum amount of power you can draw from a battery at any given moment depends on the state of charge (SoC) expressed as a percentage of total capacity. Generally speaking, you have a higher maximum power when the battery is fully charged and as the SoC decreases, the maximum power you can draw goes down as well.

This plays into how battery deterioration works over time. A battery’s total capacity will drop over time (both calendar time and cycle count), and that 8kWh needed to power the Volt for 40 miles will go up from 50% of the total capacity. As that percentage goes up, the Volt will need to expand its 50% depth of discharge to get 40 miles. Out of the factory, the battery will discharge between 85% and 35%. However if total battery capacity would degrade over 10 years from 16kWh to 13kWh (roughly 20%), then the depth of discharge would be 61% instead of 50%. We can assume the pack would go from 90% to 30% SoC, so as the battery charge state goes below 35% the pack will be able to produce less power. The issue is how much.

Could this mean that over time, battery only mode (aka Charge Depletion mode, or CD) will have decreased performance? Will 0-60 times, top speeds, etc remain constant over the life of the vehicle? GM would need to build these margins into the battery pack out of the factory, which is currently a large set of unknowns (though GM’s battery testing facility will certainly help answer these questions).

The other factor that plays into this is the cycle life. If the battery is limited to a 50% depth of discharge (DoD), the cycle life will improve dramatically over the 100% depth of discharge bench test. If a battery can go 750-1000 cycles at 100% DoD before losing 20% of the original capacity, the battery can likely take 3 times as many cycles at a 50% DoD (Motorola states that Li-Ion battery cycle counts increase exponentially as DoD decreases from 100%). GM will likely need a maximum of 3,750 cycles (40 miles each) to reach 150,000 miles, though its likely actual battery cycle counts will be closer to 3,000 in real world use. Anyone recharging the battery twice a day (recharging at work for another 40 mile drive home) will likely run up against those cycle counts much sooner.

As a risk to the program and to GM, I think the risk is fairly small. By the end of 2010, GM will have had its battery facility open for over a year. Their ability to test batteries in the worst of environments and to test cells, modules and packs and rack up the cycle counts quickly. Even if GM were forced to replace batteries after 7-8 years for those vehicles in the harshest climates (desert southwest, cold northern climates), the prices of batteries by the time 2018 or 2019 rolls around will be much cheaper (as much as 70% less than the 2010 price) and GM could even monetize the replacement if they offer a discounted upgrade battery (though I don’t know if that’s kosher/legal).

Lithium Carbonate Supplies Abound!

One of the worries I often hear about opposition to electric cars is that we’re trading one resource for another – oil for lithium. The list of countries with large lithium deposits aren’t overtly hostile to the US and its allies, however they are further left than we are (but who isn’t really?). Evo Morales of Bolivia has already stated he didn’t want outside companies to come in to Bolivia and take the lithium. But do we have enough from other sources to provide the number of lithium-ion batteries we’ll need to power the cars of the future?

An article at Seeking Alpha discusses a lithium conference held in Chile this year. At this conference, the future of lithium demands and reserves were discussed. The geologist who authored the article estimates that there are 30M tonnes of elemental lithium and 160M tonnes of carbonate (Li2CO3) – the actual material used in the production of lithium ion batteries.

Beyond that, there is a fairly high confidence of accuracy of these claims. Drilling performed in a mine along the Oregon/Nevada border indicated that an estimate from years ago was within 10% of a recent drilling. Western Lithium is focusing in on a single deposit of lithium of around 770,000 tonnes (1.5B lbs.) in Kings Valley, Nevada, with an estimated 11 million tonnes total (25B lbs.). With the recovery estimated at 85% for this area, that’s 9.35M tonnes of carbonate. They estimate producing 20,000 tonnes of LCE per year by 2013, and at a rate of 0.6kg/kWh of battery, it is enough for 3.3 million 10kWh battery packs per year. The most recent peak in the 1990s there were only 8.7M passenger cars sold (not including SUVs, trucks, etc), so a 10kWh battery coupled with sufficient technologies to allow 40 miles per charge (increased power/kg, depth of discharge) would allow 38% of cars manufactured to be PHEVs if the market and prices allowed, and this is just from one site located in northern Nevada, accessing only a fraction of what the site is expected to produce.

Down in southern Nevada near Tonapah, there is the only existing lithium brine recovery operation in the US in Clayton Valley, Nevada, where estimates range from 2 million to 20 million tonnes of LCE. One more valley over, there is the Fish Lake Valley, which has similar concentrations of lithium as Clayton Valley. The Clayton Valley site currently produces 5,700 tonnes annually, or enough for about 594,000 16kWh battery packs per year – the first three or four years of Volt production wont exceed 250,000 units. And I still haven’t left the great state of Nevada.

So what does 160M tonnes of lithium carbonate equivalent (LCE) equate to in batteries? With current production techniques, 0.6kg of lithium carbonate will be used per kWh of battery storage capability, and 1 kg of lithium carbonate is equivalent to 0.1875 kg elemental (pure) lithium. At 0.6kg LCE per kWh, recovering 50% of the estimated 160M tonnes of LCE would result in 13.3 Billion 10kWh batteries, or 3.8B 35kWh battery packs for battery electric vehicles. There are about 1B vehicles on the planet now, and factoring in growth to 2B by 2030, it would take about 60 years to go through that amount of lithium (assuming batteries last 10 years). When you combine this with lithium recycling, the supplies are enough to last us well until we find the lithium-ion replacement technology.

So what about recovery? Even by 2030 when plug-ins and pure electric cars are 90%+ of the sales (as Google.org estimates), that would mean an annual US vehicle production of 12 million vehicles per year would require almost 11M vehicle battery packs, at an average of 15kWh each, that’s 165 million kWh, or 99 million kg, or 99,000 tonnes just for the US. Worldwide, by 2020, its estimated that lithium-ion batteries for vehicles will require at most 70,000 tonnes per year, while various mining industry groups claim to be able to ramp to the high figures needed just themselves. This area appears to be well covered.

Finally is cost. Even at $250/kWh (the 2020 industry target price), lithium’s only about 2% of the battery price. The price for LCE is about $8/kg, or about $4.80/kWh, even doubling it doesn’t have a much of an effect on the price – from 2% to 4% of total cost in 2020.

We will still need to figure out what will come after lithium, though some companies are already laying the groundwork for the post-lithium era. But the doomsayers don’t have much of a leg to stand on, and we still haven’t got into harvesting lithium from seawater (at a first-generation technology price of $22-32/kg, with enough lithium for 18 trillion Tesla Roaster battery packs).

A123 Battery Technology – LiFePO4

A123 systems has been a big name in batteries since the plug-in revival started again two years ago. One unique property of the A123 batteries is that instead of prismatic cells (that is, rectangular prism), they’re cylindrical, like the AA batteries that go in your digital camera.

Their chemistry of choice is lithium iron phosphate, or LiFePo4. Their current premier cell that they have specifications available for is the ANR26650M1A, or just M1 cell. This cell packs about 7.6Wh in one cylinder about 6.5cm tall (2.55 inches) and 1.5cm in diameter. That means you’d need 2,100 cells to make a 16kWh battery, and that many cells would provide more than necessary power to supply the electric motor.

One of the rumored reasons why GM chose LG Energy over A123 is that because A123 was unable to produce prismatic cells, and GM needed prismatic cells to fit the necessary 16kWh in the Volt without taking up any more room than they already are. However, this is in direct conflict with Chrysler’s assertion that they are working with A123 on a prismatic cell. The M1 is also the cell that the could be in the Raser Electric Hummer H3, based on a reference to the cell in the H3 promotional video.

A123 is happy to tout their cycle life – their specification sheet has a graph showing that at 45°C (113F, not an unreasonable temperature to keep batteries at during usage) the cycle life exceeds 1000 cycles and maintained just under 90% of its original capacity. At the steady rate of decline showed on the graph, it appears the battery could get up to 1,750 cycles until capacity was 80% of original capacity at 1C charge and 2C discharge.

We’ll see if Chrysler can make it out of Ch 11 and the merger with Fiat to create these electric cars they’ve planed on making, or if A123 gets a better dance partner (Ford?) before the prom is over.

Analyzing Battery Performance Characteristics

There are several metrics to how batteries are measured. And those metrics play various roles in determining how well the batteries would (or wouldn’t) perform in an electric car. From standard hybrids to plug-ins and pure electric vehicles, they all have different battery needs.

We’ll start with the basic measurement of capacity. Your vehicle’s fuel tank might hold 19 gallons of fuel, and the battery equivalent is energy, measured in kilowatt-hours, or kWh. Sometimes the figures are offered in Amp-hours or Ah, to get kWh multiply that figure by the cell’s nominal voltage.

A laptop battery might have around 0.05kWh of energy, while the Chevy Volt has 16kWh, so you can image how many laptop batteries you would need to put in a car to get 16kWh. The biggest battery in a vehicle is the Telsa Roadster’s with 53kWh.

It is estimated that a small sedan would use about 200Wh per mile of driving, and a large SUV would use around 400Wh per mile. Those are average figures, with regenerative braking decreasing city driving figures and highway driving increasing those figures. As the vehicle weight go up, and as your driving speed increases, the amount of energy needed per mile goes up as well. Obviously, increased weight requires a greater force, and aerodynamic resistance increases as the square of speed, so the force required to cut through the air at 70MPH is twice of the force at 50MPH.

So how does all that energy get from the battery to the electric motor? It goes through an inverter to convert the DC (direct current) energy into AC (alternating current) energy to power the motor. This raises the issue of how much power can those batteries deliver at any given moment.

Reading from a battery’s spec sheet, you’ll usually find a pulse power rate. This is measured in W (for each battery) or W/kg, and is the short-term power the battery can put out. Combining this with the total number of cells or total cell weight will determine the maximum power the batteries can deliver to the motor. The motor in the Tesla Roadster is 185kW, and the Volt’s motor is about 110kW.

One of the most important battery characteristics is the energy to weight ratio, usually called energy density, measured in Wh/kg. This is the battery’s usable energy divided by the weight of the battery. This is the most critical factors when it comes to examining batteries – the energy density determines how heavy the battery is, which is a very important factor when it comes to automobiles. Closely correlated to energy density is the energy to volume ratio, measured in Wh/L, this determines how large the batteries are.

Today, automotive lithium ion batteries are approximately 70-100Wh/kg. This means for each kWh of energy storage, the battery weighs around 10kg, or 22lbs, plus other necessary equipment to connect the batteries together, to cool them, protect them in case of an accident, etc. It is hoped that energy density will increase approximately 10% per year for the next 10 years, more than doubling by 2020 and providing for cutting battery size and weight in half.

The next most critical attribute for an automotive battery is the cycle count. This is measured in the number of complete battery cycles until the battery can only hold 80% of its original capacity. A complete battery cycle is when the battery has been discharged and charged at its full capacity. So discharging a battery 50% twice or 33% three times, both equal one complete cycle. Batteries also have an expected calendar life, but this isn’t related to the cycle count.

To extend the the cycle count of the battery, you can use a smaller depth of discharge. The Chevy Volt is the perfect example. It has a 16kWh battery but only will use 8kWh, charging to 85% total capacity and discharging down to 35% for daily driving on electricity. Using only 50% of the battery capacity doubles the number of recharges the battery can withstand until it can only store 80% of original capacity.

The lithium ion battery in your laptop has a life of 18-24 months, and a cycle count of around 300. This isn’t anywhere near suitable for use in electric vehicles, so different battery formulations that last longer and have higher cycle counts are being developed. No one will really know what the Volt’s batteries are capable of until they start selling units, but the battery would need to be capable of around 3,750 recharges (a cycle count of 1,875).

California regulations require electric cars to have batteries that are warrantied for 10 years and 150,000 miles, so automakers are targeting those figures. Granted you have to live in CA or have bought it there to be covered, but because the market is so large automakers really have no choice but to match those warranty numbers.

Finally in this battery tutorial is the charge/discharge, or sometime just called the charge rate, noted as nC where n is an integer (1C, 2C, 6C). This can have an affect on the cycle count – the faster you charge and discharge the battery, the fewer cycles it is capable of. 1C is charging the battery so it will recharge in 1 hour – so an 11Ah battery charged at 11A (at the cell nominal voltage) is being charged at 1C, 22A would be 2C, and 66A would be 6C. Adding up all the cells in a battery pack would tell you what the total current the motor would be capable of receiving.

So thats it as far as this battery tutorial goes.

Sunpower publishes paper on LCOE

I just came across a whitepaper on SunPower’s website that extensively went over the Levelized Cost of Energy and how the drivers of solar power are working to decrease costs, and a glimpse of where we might end up in four years.

The report (PDF) is available and goes through the all of the steps on how to calculate the LCOE and what factors go into designing a large scale solar power system. There are a few places where I disagree with their numbers but overall the report is fairly accurate (their maintenance figures a little low – not too bad, but for us our maintenance cost per kWh is not close to one cent or half a cent as they might claim in some of their cases).

There are a few highlights to point out in this report. First was a reference to a report on panel degradation (source report PDF). They tested 23-year old solar panels and found that they had only degraded 4%. Further, there was nearly no noticed degradation from years 1 through 20, with nearly all the degradation coming in a few year window between years 20 and 22, with the last year of the survey having leveled off the degradation.

Next is that most plants are financed under forecast power production, and that is usually grossly underestimated. This I have also found to be true – our guaranteed output is far less than our actual output – by more than 10%.

The biggest item in the report is the following quote…

In SunPower’s case, the grams of polysilicon consumed to manufacture a watt at the solar cell level declined from 13 g/W in 2004 to 6.3 g/W in 2008 and is planned to decline to an estimated 5 g/W with SunPower’s Gen 3 technology now under development. By 2011 this approximately 60 percent reduction in the use of silicon, coupled with an approximately 50 percent decline in the price of polysilicon, will independently drive large cost reductions for PV panels.

So while panels might have cost $5-6/Wp back in 2004, the increase in cell efficency, reduction of the quantity of bulk silicon used as well as the reduction of the cost of silicon due to the crappy economy and oversupply due to added manufacturing capacity, the cost of a panel could drop down to $2/Wp, and reducing overall costs from $7-8/Wp to $5/Wp and closer to grid parity.

While this is sort of a PR/promotional piece, the numbers in the report are backed up by my real world experiences. As long as the world doesn’t fall apart anytime soon, solar power is on track.

[Edit 6/16: Updated link to Sunpower LCOE paper after their website redesign]

Coolerado

My boss at work turned me on to Coolerado air conditioners. The principle behind the cooler is novel, and seems to not be some vaporware or scheme (they have recieved awards and letters from the US Department of Energy and the Governor of Colorado). While I’ll be skeptical until I see a real unit and can measure things for myself, it does seem like its a real working product. Not only that, but their test system uses “all of the buffalo.”

Coolerado has posted a few YouTube videos (123) talking about their system and how it works. You can watch those or follow along with me.

Their system is broken into two parts – the fan and filter, which draw in outside air and filter it through standard filters you can buy at a hardware store. This will clean the air before it enters the home.

From there, it enters their heat and mass exchanger (HMX). This is where the cooling happens. The incoming air stream is split into channels, with half of the air being used as the “working” air stream which does the cooling work, while the other half is the product air stream (the resultant air that would go into your house).

The HMX is a multiple stage cooling system, where in each stage a fraction of the incoming air is used as the working air stream, and the rest is used as the product air stream that is cold. The working air absorbs water from the wet plate which cools the air by trapping the heat energy in the air in the water (water can hold about 100x as much heat than air can) this cools but also humidifies the air. The wet plate cools as water is evaporated from it, which cools the air on the other side of the plate.

Next, the working air that has already been humidified is used to cool the incoming air by a fraction. By reusing the “waste” air that is humid but still cooler than the warm incoming air, the Coolerado unit seeks to push beyond the “wet bulb temperature”, or the temperature of a wet thermometer bulb in an air mass. Theoretically, the wet bulb temperature is the lowest temperature you can get in an evaporative cooling system. By having a multiple stage process, the wet bulb temperature gets lower with every stage as the working air cools the air left in the system. Their theoretical minimum temperature is the dew point.

Their test system uses that humid waste air, which is still somewhat cool, to cool solar panels which power the fan and solenoid to control the water pump. As someone with extensive solar power experience I can tell you that a 10F degree drop in ambient air temperature can increase your output by 5% given the same atmospheric conditions (solar irradiation, wind, etc).

There are limitations to the system, most notaibly that it is still using evaporative cooling, and it wont be able to cool already humid air. It also requires water – their videos demonstrate a unit for 3,000 sq ft and 20 people uses 4 gallons per hour, or nearly 100 gallons per day, which is about the range a swamp cooler uses for half the size (1,500 sq ft).

There is tremendous upside – the unit uses a fraction of the power of a traditional air conditioner – as little as 10% of the standard energy. Cooling buildings in the dry summers in the southwestern US is a huge energy hog, and if the energy needs could be reduced dramatically it would be a huge relief to energy utilities who would need less transmission capacity and fewer new sources of energy.

I used about 30kWh/day (or about $3.30/day) last summer for cooling (I compared my summer and winter usage and just took the difference – 35kWh/day vs 65kWh/day), so reducing my A/C costs by 90% would result in a 3kWh/day difference between summer and winter, and reduce my monthly energy costs by $90 in the hottest summer months. And due to the lower energy variability on my bill, it would be easier to estimate and cheaper to fit my house with solar power to offset my energy usage.