Advances in low pressure hydrogen storage

I just read an update on LinkedIn from Mark Cannon, CTO at Hydrogen in Motion (H2M). His company works on the development of a low pressure hydrogen storage system. The hydrogen is adsorbed to a material. This technology is interesting because hydrogen is hard to store. You need a large volume of hydrogen to get the energy you need. For this reason hydrogen is stored at extremely high pressure. Such high pressure storage systems are very expensive.

Mark wrote on LinkedIn: "A year ago we successfully synthesized a material which adsorbed 4.2 wt % hydrogen and desorbed 70% of it at 50 bar and ambient temperatures. For the past year we have been focusing on improving the synthesis of this material and understanding all the mechanisms at play. We are currently adsorbing 5 wt % and releasing 80% of the hydrogen, effectively a 4 wt % material. Gravimetrically comparable to 250 - 700 bar compressed tanks but with a volumetric capacity better than 40 g/l. Now we are increasing material production for demonstration tanks for our strategic partners"

Now 4 weight percent (wt %) doesn't sound like much, but you have to realize that hydrogen is the lightest existing material on the planet. A fuel cell vehicle needs only 5 kg to drive about 500 km. So 4 wt % means that a storage system for 5 kg would weigh about 125 kg, which does not add too much weight to a vehicle. A high pressure storage cilinder for 5 kg weighs about the same.

Now of course this kind of storage technology has downsides as well. The number of filling cycles is limited. When asked Marked answered that "Early tests show 100's of adsorption/desorption cycles. " If a vehicle can drive 500 km on a tank, that means 200 cycles gives the tank a lifetime of 100.000 km.

Filling times are also important. High pressure cilinders can be filled in only 5 minutes. Mark did not mention how long it took to fill, but similar materials require hours to completely adsorb the hydrogen.

The main advantage of these systems is a much lower price. According to Mark: "Goals is to be half the price of compressed tanks of equivalent performance."

If filling times are a problem then you may end up with a hybrid system. Say a 4 kg high pressure cilinder and a 1 kg low pressure tank. The 4 kg can be filled quickly and the final kg serves mainly as an emergency supply in case the main tank is empty. If used, the emergency supply can slowly refill itself from the main tank after this has been refueled. Use as emergency supply also means that the number of filling cycles will not be an issue.

Hydrogen car feeding electrical grid

For the first time in Europe and possibly worldwide a hydrogen vehicle supplied electricity to the power grid. At the Green Village at the Delft University of Technology a Hyundai ix35 was connected to the electrical grid to feed it with electricity. The Green Village site is used to demonstrate new technology. The demonstration marks a step towards a hydrogen economy where excess renewable energy is converted to hydrogen and where hydrogen vehicles can supply backup power at times when there is insufficient (renewable) electricity available. This means that no conventional electric plants will be required as backup.

Dutch clean vehicle stimulus plans enable strong growth for FEVs and FCVs

Recently the Dutch State Secretary for Finance wrote a letter to parliament containing plans on clean vehicle stimulation for the period 2017-2020. His letter offers great potential for FCV (fuel cell vehicle) sales in the Netherlands. The Netherlands have the lowest average emissions for new vehicles sold in all of Europe thanks to generous stimulation for clean vehicles. Specifically fiscal stimulation is high for lease cars, which has led to plug-in hybrid vehicles becoming the most popular lease cars. This stimulation will remain intact for fully electric vehicles (FEVs) and FCVs, but the stimulation for plug-in hybrid vehicles will be phased out between now and 2019. This will lead to increased demand for FEVs and FCVs.

Starting 2019 however the stimulation for FEVs will only be applied to a sales value upto € 50.000. That will likely lead to a shift from FEVs to FCVs. Luxury FEV manufacturers (current FEV market leader is Tesla) would be wise to offer their models with a FC range extender.

If most of the current luxury FEV sales shift to FCVs in 2019, FCV sales could grow exponentially. A rough estimate of FCV sales:

2013      0

2014      2

2015    10

2016    30

2017  100

2018  300

2019 1.000

2020 1.500

Aluminum batteries might find application in hybrids and FCVs

New publications about battery breakthroughs appear regularly in the media. In practice however not much has changed in the field of battery technology in the last few years. Recently Stanford University came up with a new story.

This time the story is about the aluminum-ion battery. Stanford has developed such a battery that they present as very promising. Of course they are looking for investors to help further develop this technology into actual products.

The main difference with the commonly used lithium-ion battery is the use of aluminum instead of lithium.

Advantages
Aluminum offers a number of advantages compared to lithium. Aluminum does not cause a fire hazard in case of incidents. Another important advantage is the shorter charge time: Stanford has succeeded in charging the battery in only a minute. Finally the battery has a much longer life time than lithium batteries. Standford's battery could withstand 7,500 cycles without capacity decay, where a typical lithium battery lasts about 1,000 cycles. Finally aluminum is also cheaper than lithium.

Disadvantage
The major disadvantage of the aluminum is the lower voltage, about half the voltage of a lithium battery. That also leads to lower battery energy density. In other words: more batteries are needed to store the same amount of energy. That is a key disadvantage which disqualifies this battery for most of the popular applications of lithium batteries, such as mobile devices and electric vehicles.

Applications
Still there are applications where the advantages of this aluminum battery seem more important than the disadvantage. Stanford suggests using this battery for storage of excess electricity from sustainable energy sources such as wind and solar. In such a stationary application the size of the battery stack is much less relevant and life time is more crucial.

Hybrid vehicles
Although aluminum seems unsuitable for electric vehicles and plug-in hybrids, I do see opportunities for vehicle applications. Hybrid vehicles without a plug such as the Toyota Prius have a relatively small battery which can be charged and uncharged multiple times during a single trip. And it is crucial that the battery can be charged quickly as this is needed to store breaking energy. The life time of lithium batteries in hybrid vehicles is a major bottleneck. In Toyota's hybrid synergy drive system the potential capacity of the batteries is only used for a small amount in order to extend battery life. In Honda's IMA (Integrated Motor Assist) system it is even worse. Battery failure is one of the main reasons why the IMA system is unsuccessful on the market. Aluminum batteries might offer new opportunities for such hybrid systems.

Fuel Cell Vehicles 
Another type of vehicles that might see use of this type of batteries is the Fuel Cell Vehicle. FCVs are in fact hybrid vehicles which use a lithium-ion battery to store energy which can be used to improve response to the gas pedal. The battery is charged from breaking energy or when you let go of the gas pedal because the fuel cell doesn't stop producing power immediately. Just like ordinary hybrid vehicles, FCVs have relatively small capacity batteries that are typically charged and uncharged multiple times during a single trip.

Hyundai releases new European Tucson/ix35 FCV price

Earlier this month Hyundai announced to slash the Korean price of their Tucson Fuel Cell by 43% to the equivalent of US$ 77,000. Yesterday Hyundai announced the new price in Europe: € 55,000 (US$ 62,700). In the Netherlands that results in a consumer price of € 66,550 incl. VAT. In Europe the Tucson is called ix35. In comparison the Hyundai Fuel Cell is available in the USA for lease only at a monthly price of $ 499.

The new price is close to being a competitive offer to traditional cars with combustion engines. If Hyundai doesn't lose too much on it, it would mark a significant step towards making fuel cell vehicles competitive, although there still is a long way to go. The ix35 with combustion engine is available in the Netherlands at prices starting at € 27,495 (incl. VAT).