The hydrogen economy myth-part 2

DSC_1030_opt

Plenty of water- what’s the problem?

In the last post we had a look at the background science which is necessary to consider the question of the hydrogen economy.  Before we look at the issue of cell efficiency and some of the other problems we need to introduce one more equation.   In a fuel cell we are dealing with electrical work and the following equation relates free energy (useful work- see last weeks post) to the voltage across the electrodes.

ΔG= -nFE

where E is the voltage difference generated between the anode and the cathode, n is the number of electrons and F is a number known as the Faraday constant which is a measure of the electrical charge per mole of electrons.

If we calculate E for the hydrogen fuel cell reaction given last week we get a theoretical maximum voltage of either 1.229V or 1.18V depending on whether the reactants are in a liquid or gaseous state.  This does not sound like a lot, but in actual fact is not a problem since individual cells can put in parallel or series to build up the current or voltage.

What is more important looking at our hydrogen fuel cell is that of cell efficiency.  Working out the maximum efficiency for the reaction is easy.  ΔG and ΔH are known and are listed in the thermodynamic tables.  Dividing ΔG/ΔH and multiplying 100 gives a value of 83%.  Since this reaction goes both ways its the same efficiency both ways.  So if I was to take 1kW of electricity and use it to convert water to hydrogen its easy to see I would have lost 17% of my energy and be left with the equivalent of “830 Watts” of hydrogen.  Converting it back to electricity using the reverse of the first reaction in my fuel cell would leave me with 83% 0f the 83%, this is 69% of our starting energy (rounded up).

Nearly 70% sounds pretty good.  However there are a whole heap of other losses that have to be taken into account.  These are briefly;

  • Internal resistance of the electrical circuitry in the fuel cell and electrolyser.  Unless and until high temperature superconductors are developed there is not really any way of stopping losses of this type.
  • Internal (ionic) resistance of the chemical reactants in the electrolyte.  There is no way round this problem.
  • Activation energy losses of the chemical reactants at the electrodes.  Energy is needed to get a reaction going (think of striking a match).  The platinum electrode reduces the energy required but cannot eliminate it.  This can be influenced by electrode and   physical conditions in the fuel cell but never completely eliminated.
  • Mass transport losses.  As reactants are used up localised concentration gradients are set up in the cathode and anode compartment.  Reaction conditions may be able to reduce these losses but not reduce them.
  • Oxygen can cross the semi-permeable membrane into the anode compartment.  Cell design can reduce losses from this source.

All this reduces the theoretical efficiency above massively to less than 50% for a PEM fuel cell.  If the losses in the electrolyser are as high then its an easy calculation to see only 25% of the original electrical starting energy is returned and that the hydrogen economy starts to look like a myth.

Yet another post will be necessary to look at some other practical problems.

Neil

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One thing we have learnt this week- nuclear power

There has been lots going on in the energy world this week and even in the Christian world that is relevant to this book so it saddens me to have to return to nuclear power again.  The reason for this  is that Hinckley C has been waved through by the EU commission.  This looks like a very bad deal for the consumer at nearly 10p/unit for 35 years (inflation linked) and sets a precedent for other proposed nuclear power plants which would push up energy prices even more.  We have covered all this on the blog before and nuclear power in our book which brought us some criticism.  However, I see no reason to change our books stance, nuclear power is not the answer to climate change or energy security.  The technology appears expensive (installation cost) but if the cost per unit is really as small as I calculated the consumer is being ripped off*.

However according to the EU the cost of construction of these nuclear power plants has soared by 50% with almost the same in contingency payments being put on standby (surprise, surprise).  I will be very surprised if this does not require a taxpayer bail out mid-way through and there are huge construction delays.  Delays that have happened with the same reactor in France (x2) and Finland.  Then how EDF etc. will sell their power is also a mystery.  By the time these nuclear power plants have been built all renewables will be cheaper with the possible exception of offshore wind and very likely wave/tidal.  Even these could be on the way to being competitive.  All other forms of renewables will be subsidy free long before 2023.  We have also seen the first signs what I call the German conundrum here over the last week.  Briefly windpower overtook nuclear in output.  However,  that is not the main significance.  The problem of what to do with excess power was.  The wholesale price on the grid plunged to as low as 1p/unit.  We sold the excess to the French this time but without planning more energy storage we will have big problems in the future.  Nuclear power proponents will argue that nuclear provides more valuable base load.  But in 20 years time we are likely at times to have a vast excess of renewable electricity hitting the grid and its far from impossible to see nuclear power plants having to go off-line.  It takes weeks to restart them although EDF managed to arrange a payment even when off-line I believe as part of the deal.

A last thought it seems crazy to go ahead with new plants when we have not decided what to do with the waste…  From a Christian perspective this seems like very bad stewardship.

* does not include interest charges and cost of disposal of nuclear waste which the companies involved have to fund under the deal.

Neil

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The hydrogen economy myth-part 1

Fuel_Cell_Apparatus-_Pressurized_Liquid_ReactantsBeen having a bit of a blether about the hydrogen economy recently after a supposed breakthrough in hydrogen production at Glasgow University.  This got me thinking about this whole hydrogen economy myth which we covered in our book.  I’m afraid these two posts are going to be complicated so if you don’t like science leave now…

For the purposes of these posts we will mainly be talking about fuel cells and more specifically proton exchange membrane fuel cells (PEMFC’s).  These have a platinum anode and cathode separated by a semi-permeable membrane (usually TEFLON with sulphonate groups added).  The platinum acts as a catalyst.  To make hydrogen we use an electrolyser.  In this the platinum anode and cathode are in the same compartment.

At the anode the reaction (technically an oxidation reaction) is;

2 H2O(l) → O2(g) + 4 H+(aq) + 4e

At the cathode (technically a reduction reaction) is ;

2 H+(aq) + 2e → H2(g)

combining these two and balancing gives;

2 H2O(l) → 2 H2(g) + O2(g)

In the fuel cell all the above are reversed.  At the anode hydrogen is split by the catalyst to protons and electrons.  The electrons flow through the conductor joining the two and some are used by us to do “useful work”.  At the cathode oxygen, electrons from the circuit and protons which have migrated though the semi-permeable membrane combine to make water.  The idea is that the semi-permeable membrane allows the protons to migrate to the cathode compartment where it combines with the hydrogen and oxygen in the reverse reaction but does not allow the oxygen to enter the anode compartment.

All chemical reactions have three criteria that are vital.  The first is kinetics, that is the speed of the reaction.   The second is the thermodynamics of the reaction.  This is whether the reaction is energetically favourable.  Very importantly thermodynamics also has a bearing on the maximum efficiency of any chemical reactions and how much energy can be produced.  The third is where the chemical equilibrium lies i.e. whether the reaction intrinsically favours formation of the products or the reverse.  Both the forward and reverse reactions above require a catalyst.  This speeds up the reaction (kinetics), but has no bearing on the thermodynamics of whether the reaction is favourable.  Most reactions are reversible.  As reactants proceed to products if the products are not removed the reverse reaction will occur more and more until potentially an equilibrium is reached with no overall change.  Equilibrium however can be related to thermodynamics.

Splitting water to hydrogen is not energetically favourable and spontaneous change will not occur, therefore energy in the form of electrons has to be provided.  The reverse reaction is energetically favourable and it produces energy in the form of electrons.

To finish part 1 of this post, thermodynamics has two laws (actually three but the third is irrelevant here) and three components (enthalpy (H), entropy (S) and free energy (G).

The first law says that energy can neither be created or destroyed.  This has a number of  connotations but one is that it does not matter how you get from reactant to product H, S and G are the same by whichever route you go.

The second states that no spontaneous change occurs unless the entropy in a system increases.

The three components are heat (self-explanatory often reactions produce or require heat).  Entropy or disorder is slightly harder to visualise.  The greater the disorder the greater the entropy.  If you have gas in a cylinder its entropy is low, open a valve and its entropy increases to the maximum extent possible as gas molecules exit chaotically  filling the space.  Free energy is the amount of energy available to do “useful work”, in our example above the electrons liberated as hydrogen is split into protons and electrons.

The three are related by the following equation;

ΔG=ΔH-TΔS

Δ means sum of the change over the reaction between the start and finish and where T is the temperature (usually taken as 25ºC) at which a reaction occurs.  For spontaneous change to take place ΔG must be negative.  So in our example above;

H2 + O2 -> H2O

must have a negative value of ΔG.  The more the equilibrium moves towards the products the more negative ΔG will be (up to a theoretical maximum).  (I won’t bore you with the equation linking chemical equilibrium and thermodynamics.)  Equilibrium cannot ultimately trump thermodynamics in making a reaction occur, but can influence it.  Reaction conditions can be tweaked to maximise all the above, using other compounds to “donate” free energy or heat or pressure.  In part 2 of the hydrogen economy myth I will look at maximum and practical efficiencies and why in my view the hydrogen economy doesn’t add up.

Neil

clipart from openclipart.org

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One thing we have learnt this week- why are oil prices so low?

Why are oil prices so low and why are they falling?  This is particularly surprising with so much war in the middle east and tension in the Ukraine.  There is almost no oil coming out of Libya due to its civil war.  There has been huge disruption to the flow of oil from the northern Sunni and Kurdish regions of Iraq, the is continuing trouble in Nigeria, Syrian oil is not leaving the country (if it is produced at all), there is a shaky truce in the Ukraine and there was a recent war between Israel and the Palestinians.  Any one of these events should send the oil price sky high.  They haven’t, after a long period when Brent crude was stable at around $108-110/barrel its now in the low 90′s.  An analyst on the radio suggested last week that oil prices might fall as far as $85. Natural gas prices are also falling.

The first thing to say is this gas and oil prices are still high by historical standards and when Andy and I wrote in our book the days of cheap energy are over we were not exaggerating.  The graph below shows historical adjusted oil prices and the current price is still high by any standard.

oil price chartThe reason for this fall in oil prices could be for two reasons, the first is unconventional shale oil production in the US, the second is increased OPEC production.  The first reason is logically not correct.  Oil production in the US has increased dramatically since 2008 (BP Statistical Review of World Energy 2014) and this has had no discernible effect on the oil price.   At least it has not lowered it, the dramatic fall in energy prices in 2008/9 was due to the global slump.  Oil prices recovered when Quantitative Easing (QE) was used by the US and UK governments and the global economy recovered somewhat and as I wrote above have been remarkably stable until recently (despite an economic slowdown in China and the EU).  QE is still being used in the US.  The reason for decreased oil prices is that Saudi Arabia is pumping more oil.  The questions are why and for how long?  Saudi Arabia is using a lot more oil itself but needs much higher prices than the current oil price since its cash reserves have shrunk.  The reason why Saudi Arabia periodically pumps more oil to lower the price could be they are worried that rocketing prices will lead people to look for alternatives.

My suspicion is that they have both electric cars and oil fracking in their sights.   With an expected huge fall in battery prices over the next few years high oil prices would make electric cars look very viable.  Its also interesting to note that fracking for oil relies on high oil prices, it needs oil prices somewhere in the $80-90 range to be viable.  The question is how low and for how long will the Saudis allow the oil price to go and by doing this how much are they depleting their reserves?  Saudi Arabia will not be able to do this for ever.

Neil

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Is the current energy generation model going to break?

954838_204501379701698_1765426126_nIs the current energy generation model going to break?  Maybe not immediately but over the next 10 years?  This is the question many free market analysts are starting to ask.  Over the last decade but with increasing speed over the last 5 years the cost of renewables, especially solar, has fallen.  Solar by 80%.  Much of this massive increase in solar capacity is distributed generation, that is its on the low voltage distribution network.  So its its relatively small scale with the largest arrays being ground mounted at the 5-10MWp scale.  Much of its on people’s roofs and sheds or in their gardens at the kW scale.  Its this that should worry the utilities with their current energy generation model.  This existing model goes all the way back to Edison. The big boys generate lots of power in large power stations and sell it to us.  Once lots of people start generating their own electricity in large quantities things start to get interesting.  Instead of power flowing one way, power is flowing in all directions.

Many people have dismissed micro-generation has being pointless since each individual array generates so little compared to a large power station.  But lots of small arrays add up and of course you are cutting the demand for centralised generation.  We have seen this in Germany with at weekends huge amounts of solar generated electricity hitting the grid.  This summer most of electricity generated was solar in origin on some days.  The problem is what to do with this surplus power?  The best thing is for people to use themselves, with most feed-in tariffs this is what makes sense.  In our household we do everything we can to achieve this using the breadmaker and washing machine during daylight hours.  But even with a small system its impossible to stop “spill over” onto the grid.  The obvious thing to do is to store the power, which is what they are encouraging people to do in Germany (even on a micro household scale)*.  The problem is that the current technology (special lead acid batteries) are bulky, expensive and heavy and in any case don’t last more than about 5 years even if they are very well maintained (although they are almost completely recyclable).

What may cause the current generation model to break is not just solar power but cars, or more precisely electric cars.  For the reasons outlined above no one is going to use lead acid technology to power a car.  The only game in town is lithium batteries (although other battery technologies are frequently mentioned).  Up until now the cost of this technology has been prohibitive which is one reason electric cars have not sold well (the other being range).  However, the manufacturers are starting to ramp up production and with this the cost of this type of battery is set to plummet.  If there is enough lithium for cars and other energy storage uses then once the cost is competitive (estimate 2020), then demand for centrally generated electricity will fall drastically as millions of people generate their own power during the day and use it at night.  The current energy generation model will break.  We have seen the early signs of this in Germany.  At peak times when the utilities make most of their profits they cannot give the power away.  Large plant such as coal fired power stations are being shut and at least one of the big utilities (RWE) has made huge losses.

Like any market disruption such as mobile phones this will have its plus and minus points.  On the plus side electricity should be more affordable for millions as well as being green.  On the minus side we still need large scale generation and only the utilities have the financial clout to build offshore wind farms and the up and coming technologies such as wave and tidal power.  If they are struggling who is going to invest in these and the grid which we will still need?  Small scale storage is never going to make us totally autonomous especially in winter when PV output is low, but the signs are it will break the current energy generation model.

Neil

* not only in Germany my solar installer offered me this, but for the reasons outlined above I turned him down.

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One thing we have learnt this week- Community energy comes of age?

wind and solar in GermanyThis week community energy has been in the news.  My attention was drawn to the opening of a small hydro scheme in the north of England.  In of itself its of interest since it uses an existing dam which has been converted to allow electricity production (43kWp).  But as it happens this week the UK government has been emphasising its support for community energy.

By community energy we mean energy production in the hands of predominantly (but not exclusively) the local community.  This is very common in Denmark and Germany where most solar and wind schemes are owned by local or regional groups.  In the UK and the US wind and solar schemes (along with fracking) are carried out by large companies coming in.  There is little community involvement or benefit so its hardly surprising that that there is a lot of resistance.  There are a growing number of exceptions.  In Fintry, Scotland the community accepted a wind farm but only if they owned one turbine.  The income from this is spent on energy efficiency and micro-generation in a community off the natural gas grid.  In Gigha after a community buy out the community put up three large turbines (the money is used in the same way as Fintry).  Bay wind bought out a small wind farm in Cumbria and through a company they set up “energy4all” help others to do the same.  The transition movement has also been involved in solar schemes in urban areas in such places as Lewes and Cheltenham.  Nevertheless community energy currently makes up a tiny minority of energy production.

Its still far too complex to set these community energy schemes up.  You can see the evidence for this in the above hydro scheme.  The community had been thinking about since 2008.  Funnily enough I have heard money is not the issue.  After the financial crash with bank interest rates being so low renewable energy has offered a far better rate of return.  The complexities are legal and grid related as well as to do with changes in renewable policy.  DECC want to see 3GWp of community energy projects over the next 6 years partly so that there is more competition for the big six energy suppliers and help to bring down energy costs.  Whether this will be possible without a lot of help and simplification of the rules remains to be seen.

Neil

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LED street lights

2014-09-21 09.05.05I’ve just returned from a short visit to Birmingham and discovered the city council are replacing all their old street lights with LED street lights.  And not only Birmingham, Liverpool and Warrington are doing the same.  The carbon savings are said to be at least 60% but the cost savings despite the high start up expense  are enormous as we have covered previously on this blog for domestic situations.  Street lighting is on so much all the year round (but particularly in winter), despite the cheaper electricity that councils will buy the savings will be very fast.

The articles linked to above said that LED street lights produce brighter light than the old lighting and are therefore safer.  The picture shown at night suggests that.  My experience was that it was slightly worse or about the same.  It depends on the spacing of the lamp posts and obstacles like trees.

The light produced by the LED street lights I saw was not warm white but that produced by cycle lights.  However, this is perfectly adequate for the purpose and looks to all intents and purposes like moonlight.  If more councils decide to install LED street lights  then not only will we see carbon savings but also a continuing fall in the peak electricity demand.

Neil

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One thing we have learnt this week- population increase

stork babyAmid all the news about a certain event today the Guardian had one article that stood out on population increase.  The consensus up until now has been that population will peak sometime this century, probably about 2050.  The team behind this research break this consensus saying that population increase will continue.  For the first time?! this team have used statistics to arrive at confidence bands on the future path of any population increase.  (By the way it is my view that in the Guardian link above these confidence bands are mislabelled the 95% bands should be nearest the regression line.)

If the fertility rate can be reduced to 2.1 live births worldwide then in time the population would stabilise, then decline as the existing elderly population died.  The good news is that in most parts of the world its already doing so with the exception of sub-Saharan Africa.  However, a certain degree the effects of population depends on where you are born.  The ecological effects of being born in the rich west are far greater than someone born into poverty in sub-Saharan Africa.  Nevertheless increased population in this part of the world will still make demands on the food system and ecology.  There is also the issue of rising incomes in developing countries leading to changes in diet, particularly higher meat intake.  This has also had huge health implications.  Of course population increase also has energy security and material shortage implications.

The problem with population increase is that there are in many ways little we can do about it.  Lowering the growth rate depends on the actions and the economies in high population growth countries.  Experience has shown again and again that as countries get richer, women get better educated and access to contraception increases, the birth rate falls.  The problem is as countries get richer they want to eat more, particularly meat.  This might undo the previous actions.  This is where we come in.  In the words of Gandhi we need to “‘Live simply, that others may simply live”.

Neil

Includes adapted excerpts from our new book.  Image from openclipart.org.

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Energy conservation

DSC_1734As Autumn comes around again I start to think about energy conservation.  There is talk about power cuts in the UK being more likely this winter.  Two nuclear power stations have had to be shut down for repairs and a coal fired power station is off line due a major fire. All this raises the threat of power cuts as capacity is tight.

Of course the best form of power is “negawatts”, i.e. not using energy in the first place and this is where energy conservation comes in.  Our energy consumption (or at least electricity consumption) hit an all time low about 8 years ago.  Since then its been on an upward trend although with ups and downs.  The reasons for this are simple.  The children were growing up, staying up later and using more energy. Even when one left home our electricity consumption carried on going up.

Installing second PV system a few years ago didn’t stop this relentless rise in electricity consumption.  I was disappointed but not surprised by this.  My explanation was that at the time we had nailed down our electricity consumption as far as we were able.  But as a Christian who was concerned about climate change and the global energy crisis, I started to look for solutions.  We had swapped our normal incandescent bulbs for GLS ones that used 35% less electricity, put in CF bulbs in many places and bought some LED’s.  None of this made a difference in that electricity consumption was still rising, although it will have stopped it rising still further.

It was a delightful surprise then when my electricity consumption has started falling this year and my energy conservation efforts are starting to bear fruit.  Its not that there has been more sun this year and more homemade electricity, this year is going to be worse than last year.  The only explanation I can up with is that the number of LED’s as I keep gradually adding them has reached a critical level which shows. The economics stack up as well.  Why not thinking about buying a few?  Energy conservation could well be the future.

PS.  don’t be put off by the slightly weird colour of the picture of a bulb above its just the contrast in the shot, the light is identical to an incandescent bulb.

Neil

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One thing we have learnt this week- the big energy debate

bedroom wallThe Guardian has started a year long project called “the big energy debate”.  What is worrying and interesting is that despite the fuss over energy prices over the last year how disengaged people are from all the whole energy problem.  As part of the big energy debate the Guardian has done some opinion polling.  An astounding 2% of people thought energy was one of the most important issues facing the UK.  This was despite over 80% being concerned about bills.  But only 32% thought it would influence the way they vote.

People seem unaware of their acute dependency on energy for example look at mobile devices.  These take energy to manufacture, transport and above all use, with constant recharging.  There are some encouragements from the big energy debate survey, there was very high support for renewables, particularly solar.  Nuclear, biomass and coal were the least popular with fracking in between.  Fracking other polls as well as this suggest is a fairly even three way split between don’t knows and antis/pros.  Once it arrives in your backyard though its very unpopular.

We have a triple dilemma of affordability, security of supply and climate commitments.  These often seem to contradict.  But people do have to get their heads around this issue, the days of endless cheap energy are over.  Hopefully the big energy debate will help to move things forward.  It seems to be taking place on twitter and if “No oil in the lamp” can work out how to use it, it may well join in.

Neil

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