ZSW is to study a multi-energy dispenser which would supply grid electricity, batteries, hydrogen and methane to power low-carbon vehicles
While there will be always be an appetite for rapid refuelling and recharging of EVs, the technology is highly disruptive to the current business model of fuel retailers. Instead of pulling in and refilling an ICE in minutes, battery EVs are much more likely to be charged upon arrival at their destination, or indeed once the driver returns home. And even though hydrogen FCEVs or compressed natural gas (CNG) vehicles fit the current retail model almost exactly, they are unlikely to be present in quite the same numbers as existing ICE vehicle fleets.
That leaves the question of what filling stations of the future might like look. Scientists at Germany’s Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) have set out to find out.
Launched in mid-February, their new project intends to create a “fuel pump for the future”. This dispenser would be capable of delivering electricity, hydrogen and methane in the most efficient, cost-effective and functional ways.
This “multi-energy dispenser” would rely on power from the grid, but could also store or convert that electricity into other fuels when economic to do so. This would also help each of the electricity, transport and gas networks decarbonise through a linking process known as “sector coupling”.
ZSW says that the system would store grid power in a large stationary battery when supply is greater than demand, and dispense it when demand is greater than supply. “If the battery is full and recharging electric cars cannot deplete it, this green electricity will be converted into hydrogen in a second step,” ZSW’s Dr. Ulrich Zuberbühler explained.
The units would also be capable of a third stage, producing methane when the hydrogen storage tank is full and demand from fuel cell vehicles is low. Carbon dioxide would be added to the hydrogen to convert into methane which could be used by CNG vehicles. natural gas cars can readily use it.
If vehicles are not using the supply sufficiently, the surplus gas can be stored and then piped into the natural gas grid when the storage tank fills up.
“With our project, the coupling of the electrical grid with mobility will not be limited to electric cars,” added Zuberbühler. “The other alternative drives will also benefit from it.”
One concern with such a system is inefficiency. Storing grid electricity in batteries is relatively efficient, but converting it to gases less so. As such, the researchers are also investigating how to minimise energy losses.
Battery storage loss should not exceed 10%, they say, but stages two and three – conversion to hydrogen and then methanation – will only become an option once demand for electrical power has been met. Electricity can then be converted to hydrogen at around 75% efficiency, and roughly 60% for methane.
However, once converted, these gases are “long-term, zero-loss stores of energy” – and efficiency increases by a few percentage points when the waste heat generated during the conversion process can also be recaptured.
ZSW intends to improve the efficiency, service life and cost-effectiveness of the two main components – a high-pressure alkaline electrolyser and a plate methanation reactor – and test them on a 100-kilowatt scale.
However, electrolysis and methane synthesis will have to take place separately, and require some form of hydrogen buffer or intermediate storage facility. ZSW says it will develop a concept for this and assess its safety.
The researchers will investigate the technology over the next three years, with results tested at an on-site demo facility starting in 2020.
Funding for the project comes from a joint initiative of the German Federal Ministry of Education and Research and the Federal Ministry of Economic Affairs to promote solar-equipped and energy-efficient buildings, and is providing €1.3 million (US$1.6 million).
The idea of a singular energy dispenser unit to serve multiple low-carbon vehicles is a logical one. However, building them effectively will require a large amount of additional infrastructure – batteries, control systems as well as multiple product storage tanks. ElecTrans wonders how many fuel stations have a sufficient footprint to be able to incorporate these facilities.
Energy losses and process efficiency are also an issue. Although ZSW intends to increase efficiency in its pilot study, commercial viability would require regular periods of very cheap electricity, as well as the time necessary to produce and compress the gas products, and a predictable flow of customers. A final model will of course depend on scale and final yields, but the return-on-investment period for even one facility could be considerable.
There’s also the issue of time. As stated above, even high-powered fast charging of EVs is likely to take 15-20 minutes, versus the five or so minutes required to fill up an FCEV or CNG vehicle. That makes EV charging far more suited to parking bays than forecourts.
Nevertheless, co-locating these facilities in large car parks may make sense. An abundance of space and regular predictable traffic would suit the business model, and would enable flexibility; gaseous fuels could be dispensed from a forecourt areas while EVs are parked up. Whatever the final proposition, we’re very interested to see what ZSW comes up with.