the sinclair c5 - 20 years ahead of its time ?

Ben84

A lot of commercial hydrogen is being made from splitting natural gas, which is of course a limited fossil fuel and allegedly contributes to global warming. Splitting the gas also consumes energy, which is normally from one of the usual fossil fuels.

In this case, it's not very clean and not very environmentally sound.

You can also make hydrogen by splitting water, which at least uses one renewable raw material, but the process needs energy input in the form of electric, and this currently comes from the usual fossil fuels. It is reasonably efficient, if I remember rightly about 70% efficient, but the energy losses are not insignificant.

The suggestion we could make hydrogen for transport with electric from solar panels is impractical. The average car engine is anywhere from 35,000w to 200,000w, depending on the size and type of car. The Ford Ka, which for many of us is considered one of the smallest yet still useful cars starts at 37,000w for the smallest engine size available, 1.3L. Price up 37,000w in solar panels, then take in to account that they won't run at full capacity for most of the year in most locations, so you'd need to buy the amount that yield an average of 37,000w in your location. You'll also need to account for the losses from the solar panel's own transformer, and then the 30% that is lost when the electric is used to make hydrogen. I expect the total cost of this set up to cost more than every house on the average street, and also require them to be demolished to make room for it too. You would also only be able to drive your car for a modest amount of time compared to now. Many people might not even make it to work and back.

Sadly, cars that run on hydrogen made from solar power seem unlikely to ever become reality. These politicians and energy companies who routinely pull out the line "hydrogen can be made from sunlight and water" are talking nonsense, because the real figures and numbers make it physically and economically impossible beyond any possibility. Not a bit far fetched or implausible, I mean totally absurdly unrealistic.

I don't believe the hydrogen from solar power idea was created by a serious scientific study, or would even be claimed possible by any real scientist who had an appreciation of the energy consumed by transport and the energy available from solar power. It's a bit like saying let's launch a space shuttle with the batteries in your walk-man.

I don't have must enthusiasm for the claimed hydrogen economy. To make it from water will require vast amounts of electric, and if we can find a plentiful and environmentally sound supply of electric, we might as well have an 'electric economy' and power everything with that. Why waste energy turning it in to hydrogen. Anyway, until the vast and environmentally sound electric supply turns up (so far there are no signs of it), the hydrogen economy is fictional and unrealistic at best. At worst it, and it's supporters could be accused to deceiving people.

The immediate and I suspect only answer to our dilemma, our millions of cars and how to power them, is going to be natural gas, but that is still a fossil fuel.

freddykruggar

here you go

http://www.youtube.com/watch?v=efCelx7qe_M

mech_2

Ben84 wrote: »

A lot of commercial hydrogen is being made from splitting natural gas, which is of course a limited fossil fuel and allegedly contributes to global warming. Splitting the gas also consumes energy, which is normally from one of the usual fossil fuels.

In this case, it's not very clean and not very environmentally sound.

Agreed.

You can also make hydrogen by splitting water, which at least uses one renewable raw material, but the process needs energy input in the form of electric, and this currently comes from the usual fossil fuels. It is reasonably efficient, if I remember rightly about 70% efficient, but the energy losses are not insignificant.

I think the theoretical maximum is meant to be 80%-90%, putting it on a par with batteries. The main problem is storage.

The suggestion we could make hydrogen for transport with electric from solar panels is impractical. The average car engine is anywhere from 35,000w to 200,000w, depending on the size and type of car. The Ford Ka, which for many of us is considered one of the smallest yet still useful cars starts at 37,000w for the smallest engine size available, 1.3L. Price up 37,000w in solar panels, then take in to account that they won't run at full capacity for most of the year in most locations, so you'd need to buy the amount that yield an average of 37,000w in your location.

Right, I have issues with your figures here.

First of all, The 1.3 litre Ford Ka is listed as being 70bhp, which is 52,220W. I don't know where 37,000W comes from. However, that isn't a realistic indication of power consumption as it's a peak figure. At 60mph on the flat it would probably be using less than half that. Less still at slower speeds. You only need the 50kW for acceleration and climbing hills. Fairly brief usage. So you size the electric motor in your electric or hydrogen fuelcell car to match this, but it doesn't tell you how much electricity you will consume any more than the 28kW rating of my heating boiler tells me how much gas I use.

To sensibly gauge the required solar capacity you first need to know the number of miles you can drive per kWh. For plug-in electric vehicles you can find figures of between 2 miles and 4 miles per kWh for vehicles that exist today. That's mains-to-wheels, so includes battery losses. (These are proper everyday cars, not lightweight plastic tricycles which probably do >10miles per kWh).

You'll also need to account for the losses from the solar panel's own transformer,

You don't need a transformer. Just attach the panels directly to the electrolytic cell.

and then the 30% that is lost when the electric is used to make hydrogen. I expect the total cost of this set up to cost more than every house on the average street, and also require them to be demolished to make room for it too. You would also only be able to drive your car for a modest amount of time compared to now. Many people might not even make it to work and back.

Average mileage is generally taken to be 12,000 miles per year in the UK. That's 33 miles a day, averaged. Not very challenging.

12,000 miles at 3 miles per kWh is 4,000kWh. A 6kW solar array should be able to generate that in a year. When there isn't enough sun you could top up from the grid and sell the excess onto the grid in summer (obviously the grid will need some backup capacity for this to work). Is it cost effective? At £5,000 per kW of installed photovoltaic panels in a domestic system: no. Is it feasible at some time in the future? Possibly.

Sadly, cars that run on hydrogen made from solar power seem unlikely to ever become reality. These politicians and energy companies who routinely pull out the line "hydrogen can be made from sunlight and water" are talking nonsense, because the real figures and numbers make it physically and economically impossible beyond any possibility. Not a bit far fetched or implausible, I mean totally absurdly unrealistic.

That's because your figures were unrealistic.

Solar concentrators in hot countries driving free-piston stirling generators could be another option. This is already more efficient than the most efficient experimental photovoltaic panels. The problem is how to export all that electricity to places such as the UK. An energy carrier is needed. This is where hydrogen could come in useful.

anewman

No one has yet mentioned the documentary film - who killed the electric car. To be involved in this issue, this film is a *must* watch.

Watch it here, part 1 of 11 parts.
http://uk.youtube.com/watch?v=9vD33UMAtBY&feature=related

Here is a post on a forum about someone converting an old skoda, to an electric powered car and spending about £6,000 doing so http://briskoda.net/forums/project-journals/coming-soon-greatest-favorit-project-ever-probably/112799/

freddykruggar

nothing we didnt already know

Cardew

Love the bit about the Skoda project.

However it illustrates perfectly the problem of storing energy. The batteries alone weigh over half a ton, the weight of five men(or women!) each weighing over 16 stone.

Also 144 volts with that sort of power is seriously dangerous and has the potential for an massive explosion.

tonyE1

mech wrote: »

Solar concentrators in hot countries driving free-piston stirling generators could be another option. This is already more efficient than the most efficient experimental photovoltaic panels. The problem is how to export all that electricity to places such as the UK. An energy carrier is needed. This is where hydrogen could come in useful.

That is so interesting. I am a physics graduate and maybe I studied sterling engines at some time but had completely forgotton about them.

Any other exciting ideas? Its a shame that Brown et al can't be a bit more imaginative to solving the problem than chucking £100,000,000,000 at the problem which is unlikely to produce anything like the results they are trumpeting

geordie_joe

It seems the C5 isn't quite dead yet.

http://news.bbc.co.uk/1/hi/wales/south_east/7354449.stm

http://www.c5alive.co.uk/

Although I'm not putting money on electric personal flying machines!

http://news.bbc.co.uk/1/hi/technology/7481940.stm

Ben84

tonyE1 wrote: »

That is so interesting. I am a physics graduate and maybe I studied sterling engines at some time but had completely forgotton about them.

Any other exciting ideas? Its a shame that Brown et al can't be a bit more imaginative to solving the problem than chucking £100,000,000,000 at the problem which is unlikely to produce anything like the results they are trumpeting

Take a look at solar chimneys. They're an interesting power plant design that uses solar energy to make electric, and because of stored energy in their thermal mass they can maintain a good output even overnight.

Another interesting design is parabolic trough collectors. The physics and design isn't anything exceptional, but I find them interesting because they're available proven technology and they work well.

We can make useful energy from solar power, but these plants tend to be less efficient in climates like the UK, perhaps even impractical. They're also normally very large and have a modest output. A big solar thermal plant might generate 60-70 MW. A big coal or nuclear plant is about 4,000-6,000 MW. Even if we could find a design that works well in the UK, all solar plants designed so far require a lot of land, and land is limited and expensive here.

BillScarab

The obvious solution to generating large amounts of electricty without greenhouse gases is nuclear power. That has it's own problems of course.

As for why the C5 failed, would you like to be driving that on the same roads as cars? It's so low no-one would see you. It makes riding a bicycle on the roads lookpositively safe.