Thursday, July 28, 2016

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.

Wednesday, July 13, 2016

Smart vehicle to grid charging station

Electricity grid operators in the Netherlands have approved the first smart vehicle-to-grid charging station that is suitable for feed-in from vehicles to the grid. This station has been added to the Elaad's register of approved charging stations. Elaad is a collaboration of Dutch grid operators that promotes electric vehicle charging.

Last year a field test was done in Utrecht. This allowed electric cars to be used for temporary storage of solar energy for later use. The charging station is made by General Electric and is the first station to support a 3x63 A grid connection. This high current connection enables for two electric vehicles to be charged and discharged simultaneously (2x 22 kW). This gives the station high flexibility for charging and discharging vehicles rapidly when there are peaks on the electric grid.

In future the grid can also be supplemented with power form hydrogen vehicles, or solar powered vehicles. Vehicles thus play an important role in creating a smart grid that is suitable for supplying increasing amounts of sustainable electricity.

Monday, July 11, 2016

Tesla's master plan part 2

A couple of weeks ago when Tesla announced its bit to takeover SolarCity, I noted down my suspicions that Tesla would introduce a solar powered electric car. A few days later Toyota announced it's new solar powered Prius, beating Tesla to it, although with a hybrid car. A few hours ago Elon Musk seemed to confirm my suspicions as he wrote on Twitter: "Working on Top Secret Tesla Masterplan, Part 2. Hoping to publish later this week." And 2 hours later: in a tweet in response to a blogpost about the reason for the SolarCity takeover: "Kinda. Creating a seamlessly integrated Tesla battery & solar power product that looks beautiful is the reason"
Bets are still on. I don't think it's a seamlessly integrated home system. I think it's going to be an integrated system on wheels.

Friday, July 1, 2016

Nissan develops range extender on ethanol and natural gas

Nissan is developing a new drive train consisting of an electric vehicle equipped with a solid oxide fuel cell (SOFC) range extender. Nissan aims to bring the technology to market in fleets by 2020. The test runs on bio-ethanol but other fuels such as natural gas can also be used. The fuel is reformed on-board to create hydrogen which is then used in a solid oxide fuel cell.

SO fuel cells more affordable than PEM fuel cells currently used in hydrogen vehicles as they don't require platinum catalysts. Bio-ethanol and natural gas/biogas are also cheaper than hydrogen and require much lower infra structure investments.

The downside of SO fuel cells are the high operating temperature which leads to higher start-up times. Also the reformer has long response times, which limits the use of SO fuel cells in vehicles to range extenders and APUs.