@HarveyD: I disagree. The cost normally would be a factor of 2x larger without the grant. This battery is providing frequency (power) regulation. Say there are 3 significant gusts/lulls per hour that the battery regulates, then the battery gets used ~70x per day. To eliminate traditional power with wind turbines you would have to cover month long non-windy patches, so the battery would be being fully utilised say once per 30x days. Combine that and you have a factor of 4200x. All the above is very approximate and it doesn't show that the cost of the battery has to reduce by 4200x to succeed as energy storage as there are other costs like avoided power stations. But it illustrates that batteries being competitive for frequency regulation doesn't mean that batteries as grid energy storage is around the corner. Batteries are currently being used for frequency regulation, off-grid energy storage and private (grid attached) energy storage. Best bet for grid storage is where the renewable energy is equatorial solar (rather than wind) so that 24 hour storage gives you 24/7 benefits. But if you don't want brown outs and you haven't the battery to cover long periods of low RE output then you're not going to decomission traditional power stations. The best that the batteries can do for you is increase the efficiency of these stations when they are in (spinning) reserve. Getting back to batteries as regulation again. Seem like there is an analogue between cars and power systems ICE <-> traditional power stations HEV <-> traditional + battery regulation PHEV <-> traditional + renewable + battery storage/regulation BEV <-> renewable + battery storage The HEV has a small battery that is used frequenctly, the BEV a large (expensive) battery but with the avoided cost of the ICE. And not many people are ready for their _only_ car being a BEV just as not many grids are ready to be RE + battery only.

Don't see how it is storing solar energy, and nor is it a convenient hydrogen storage mechanism given that it requires light to release the hydrogen. It does provide a method for solar harvesting, but at 6% is currently worse than solar cells.

What is a good power? If 95% of your energy consumption is covered by 2kW and you are connected to the grid then does paying for 10kW make sense? You can gain a lot of press by shouting about energy storage but the specs and even the press release talk about frequency regulation. Or maybe peak shaving, but are they big enough to do that for anyone who cares? The Tesla pack made more sense to me: the business one seemed to fit a customer with solar cells that didn't operate on the weekend. But the economics still didn't add up.

Thought the comment about aviation was revealing. Power unit ffficiency might not match that of a diesel but the improved power to weight allows for lower mass and so better system efficiency in stop-go applications.

Was on a bus through the town centre that took a circuitous route with frequent stops to reduce the distance walked by passengers - and increasing the trip time. Thought something like TaxiBots would solve the performance compromise. Good to see some simulations on the subject. A driving factor for me would be waiting time - frustrating to wait 10 minutes if you are only 2km from destination. The drop-off points could be adaptive. In non-peak times the Taxis might be able to go to the door, whilst during peak times they might should a least-bad route that gets them back to the next pick up point in time.

Think you are assuming the whole world is like your own experience. Wikipedia entry on India is "almost all find electricity supply intermittent and unreliable", which is my memory from travelling 20 years ago. So there is a large market wanting many urban vehicles who are likely to be sceptical about BEV for a vehicle they need in the next 20 years. History has shown that change takes a long time, 20~50 years, so ICE vehicles will be around for a while yet and there is merit in advancing them.

@HarveyD A fuel cell would increase costs - certainly purchase cost and also running costs. Effect on GHG and fossil fuel use more marginal, depending upon source of hydrogen. Don't see why battery size would be affected in a PHEV. Though for a HEV a larger battery would be required to cope with the fuel cell being worse at load following than an ICE.

Should match age: compared 3~6 year old ICE with 0~4 year old Leaf. Should match category: compare Leaf with B-class cars. The battery is logically more equivalent to fuel tank than ICE, Okay, now I'm just being pedantic.

Good technology. Makes me wonder what Victoria,Australia recently bought and then mothballed because they found conservation was cheaper than desalination. "exclude the need to dispose of the concentrated brine reject into local waterways and oceans": What do they do with the solids if not dump in the ocean?

@Davemart Do you know which numbers to believe? A battery factory with 4GW capacity would produce ~8000GWh/year of battery on a single shift per day, 5 day working week. Is it actually 4MW, or 4GWh/year, or ...

Two concepts mentioned in article. The 48V HEV has a 20kg mass excess, unspecified battery mass or capacity. The PHEV has a 10.7 kwh battery of unspecified mass. So no typo.

Scrappage schemes don't make sense. If a banger is scrapped for a new car then there is an incentive. If a banger is scrapped for a used car, bought from someone who buys a new car then no incentive is handed out. The net results on the car park are the same but not the incentive. A friend scrapped a five year old one litre car to gain the scrappage bonus. Does not make environmental sense because any marginal gain in fuel efficiency does not overcome the energy ued in building the new car. I tend to favour fuel duties as the way to reward owners of high efficiency cars. However the life time cost of fuel may not be such a salient factor for the purchaser of new cars especially if they're only thinking of owning for a couple of years. So moving some of that duty from the fuel to the initial purchase would make sense - and be unpopular and political suicide.

@TP Agree that the 2.0 diesel would be enough oomph. Only know of it being used in transverse orientations currently though.

@mahonj A transmission line hybrid can use the electric motor as starter motor as a starter motor. The electric motor can also benefit from the gearbox. Small benefits, can't think of any bigger ones, so Alex's list does not surprise me. Would have thought the TTR hybrid was as easy to control.

If you were going to install end of route chargers then you're going to go for fast charge batteries. The higher energy extended range batteries would be more attractive for routes with no on-route recharging.

Subsidising charge points is placing a bet that BEV will come to the fore over ICE, HEV and FCV. At least for city car needs it may be the best bet going but I don't see why the bet needs to be placed yet. HEV and even PHEV can develop without the set up of charge points and fosters the development of all the electric ancillaries necessary for BEV. Old reports concluded that you got a bigger environmental benefit for your buck with HEV too - don't know if that is still true. I'm cynical on the subject. The BEV subsidies only help a few people at the moment, likely to be the same people who are vocal on the subject. Such subsidies will keep them happy and purring. Helping the larger number of unseen HEV owners would not produce such a good PR result.

I understood that a big disadvantage for front engines were the aerodynamics. The engine is at the front and you want to shove the exhaust and radiator outflow out the back (eg diffuser). Still possible but longer ducts with higher resistance required. Agree with the copensating aerodynamic advantages mentioned. Also thought you'd have a through-the-ground hybrid with rear electric motor. But if you've got only one motor/generator (that's what F1 do?) then you'd want it up the front for braking.

Lad: Agree with the 6% (relative to previous) corresponds to 1% (absolute). But you are applying the wrong percentage to the MPG, so it is 1.8 more MPG.

This compares the fuel efficiency of a diesel and petrol vehicle in pure number terms. Implicity assumes that a gallon of each are equivalent but they are not. Diesel is 12% denser and 13% higher energy density. So if you look at miles per pound then the Ram and F150 have pretty much the same fuel efficiency. I bother to complain because people frequently complain about diesel being mor expensive than petrol when on an energy basis the reverse is true (in the UK at least). With the need to compare traditional fuels with electrical and hydrogen energy I'd hoped that this misconception would be sorted out but not yet.

Good to see your positive view Henrik as I'm more cynical. The paranoia in the UK is that the energy utility market is not competitive. One tactic used is that the customer facing company points to low profits to justify reasonable competition. However the associated upstream companies make fat profits. This restructuring facilitates such a fiddle.

What do they mean by "a hydrogen-containing gas"? A gas containing molecular hydrogen (ie H2), or a gas containing elemental hydrogen (eg H2O). The comment about humid air makes me unsure. If the second case then you could use it on pure natural gas. Harvesting from the atmosphere would be a waste - anaerobic digesters and other hydrogen producing systems might be worthwhile.

The battery capacity that can be recharged at the end stations will be fully used each journey. Any extra capacity will only be utilized once per shift. So there will be a big difference in benefit and pay-back per day between these two parts of the battery capacity. So I expect that the battery is sized to what can be recharged at the end stations, that is I'd guess the buses typically stop for about 6 minutes at the end stations.

That comment puts the energy wast to heat recycling in perspective, thanks DM. However there are still the reliability issues caused by the heat cycling. So a good early application would not be a car but the APU of the plane as suggested here on GCC last month, or a long haul truck's main power unit.

Harvey: From memory the SCiB have a great cycle life, good power density but only okay energy density. Characteristics better suited to HEV rather than rather than BEV applications though they are used in the Mitsubishi MiEV. The 2MW and 1MWh scaling gives a nominal cycle time of 1 hour and so life of a bit over 1 year. Overly simplistic and hopefully overly pessimistic. Wonder if they deliberately unbalance the modules so they can measure the trade off between depth of discharge and life time.

The ICE pollution is definitely produced in the cities. Don't know where the average coal plant is located but they may be out of the cities.