VoxSolaris: The Voice of the Sun
  Global Energy Outlook: Towards a Carbon Free Economy
 

The Notion of a Hydrogen Economy

The 'Hydrogen Economy' describes a scenario in which carbon rich fuels such as oil and gas are either largely or wholly replaced with hydrogen in order to eliminate or virtually eliminate the net flow of carbon dioxide, the principle culprit of global warming, into the atmosphere. Hydrogen when burned in an engine or used in a fuel cellproduces only water and no carbon dioxide.

Hydrogen is the most abundant element in the universe but on Earth it exists only in compounds from which it must be extracted. Most hydrogen produced today comes from reforming of hydrocarbons such as methane. In this process, the hydrogen is separated from the carbon but the latter is emitted to the atmosphere as carbon dioxide. It is clear that a hydrogen economy could not be implimented by extracting hydrogen from hydrocarbons. Instead hydrogen must be extracted from compounds that contain no carbon i.e. water. But extracting hydrogen from water requires the input of energy. So hydrogen is not the primary source of energy, something else is. And unless that primary source is carbon free, hydrogen extraction would be self defeating. In fact it would actually be counter productive as such extraction processes require more energy input than is available from burning the hydrogen.

The hydrogen economy only makes sense if something is gained by converting carbon free energy sources such as hydro, geothermal, wind, wave and solar into hydrogen. And that gain is portability. The carbon free sources all depend on fixed ground or sea based installations to be of any meaningful scale. By converting to hydrogen we get a portable transport fuel. And where the source is intermittent, we also gain from having a fuel we can store and use as required.

Hydrogen though is actually very difficult to transport and store. As a result use of hydrogen 'carriers' have been proposed. These are compounds that contain significant quantities of hydrogen that can readily be extracted by decomposition at the point of use. Within the context of the hydrogen economy, it is essential that the formation of carrier compounds at the hydrogen source and the decomposition at the point of use forms a closed loop. We at VoxSolaris advocate the use of ammonia as a carrier. We set out a fuller description of this in our page on The Ammonia Economy.

The challenge

Implicit in the notion of a hydrogen economy is the assumption that we have spare carbon free energy capacity. This is far from the case. There are isolated examples of where renewable sources consistantly produce a local surplus. Most notably Iceland with both hydro and geothermal energy but also countries such as Paraguy with hydro. Both export energy. Paraguy does so directly via cables to its neigbours while Iceland exports indirectly by hosting energy hungry activity such as aluminim smeltering on behalf of global companies. Iceland could introduce a full blown hydrogen economy and is known to be experimenting with hydrogen as a fuel for vehicles with this specific intention. For now Paraguy is sticking to exporting electricity while its citizens continue to burn hydrocarbons in their vehicles. If it electolyed water instead its neigbours would probably have to increase use of hydrocarbons to make good the shortfall.

There are many more examples of where intermittent renewable sources produce localized surpluses of electricity for brief periods. And at present, the focus is on storing the electricity for later use in grid batteries rather than on storing it in hydrogen. And until the combination of renewable electricity and grid batteries exceeds electricity demand in any given locale, it doesn't really make sense to start to use electricity to make transport fuel. We have got to the point where renewables are largely economic and can expect further improvements. So the challenge of the hydrogen economy now lays only in the sheer scale of our present day and projected demand for energy forms outside of electricity and currently met by burning oil, gas and coal. The numbers are huge. There is a unit of energy called the 'toe' or ton of oil equivelent. Roughly a toe is 42 gigajoules. Current annual demand of around 33 billion barrels of oil, 8 billion tonnes of coal and 2.5 billion tons of gas add up to around 12.5 billion toe. The world population is 7.5 billion but it is meaningless to say that consumption is 1.66 toe per capita as large numbers of the world population account for very little of this consumption. In the developed countries that figure is more like 5 toe per capita - tripple the global average. There is nothing special about the developed Western countries and there is nothing special about China. The day will come when most coutries will have a developed economy and consume 5 toe per head. If you take 10 billion as a reasonable estimate of world population by say 2050, that will be 50 billion toe.

The Electric Economy

These numbers need a certain amount of interpretation. If we could massively increase the install base of renewables to the point where anything that could be done with electricity was being done with electricity, then that 5 toe per head could fall to half that figure. Fuel currenly burned to make electricity would under this scenario be directly replaced. Space heating would become dominated by heat pumps driven by electricity. Industial processes and in particular industiral chemical processes, currently one of the largest uses of carbon based fuels, will have many endothermic stages driven instead by electricity. Most vehicles would drive most of their overall mileage under electric propulsion and would only resort to a range extender and thus transport fuel for perhaps 10 or 20 percent of distance travelled. Use of transport fuel - the centerpiece of what would qualify as the hydrogen economy, would be mainly for enegy intense applications such as launching of satellites by rockets, passenger jets and military aircraft and heavy farm equiptment.

In spite of that coming down to 25 billion toe (call it 30 billion to be safe), that is still a lot of renewable energy. Something like 40 terrawatts running all day, all night and all year round! Before we even consider what any of this might cost, the first question has to be is it actually possible? Are there any sources of clean renewable energy out there that can match the scale of carbon based fuels? In terms of theoretical maximum yeilds there is just one form of energy that can be regarded as both renewable and clean, that can match the scale of fossil fuels with ease - Solar. While helpful, other forms such as geothermal energy, wind and wave power are only economic in particular locations and have maximum theoretical yeilds falling well short of that needed to replace carbon fuels. And nuclear fission is a complete non runner in our view. Building 20,000 plus nuclear power stations is almost certainly a better guarentor of man's demise than global warming. Fortunately nuclear power is too expensive and even more fortunately, the world's supply of economically recoverable Uranium is running out.

Nuclear fusion which works on the same principles as the Sun could yeild the energy required except for the fact that as of yet, it does not work. It is so far at least, the functional equivelent to a chocolate teapot. Not only do current prototype reactors take in more energy to ignite the fuel than can be extracted from the reaction, but the heat released melts the sides of the reactor! The root of the problem is that the 100 million°C plasmas continue to defy efforts to confine them with magnetic fields. The scientists involved believe reactor size is the key and have built a massive experimental reactor in France at a cost of $10 billion, to see if that will do the trick. We wish them the best of luck but fear it will be their biggest and most expensive chocolate teapot yet.

But Solar can match the scale of oil because the Earth receives an average of 1,000 watts per square meter for an average of 12 hours per day, more at the equator, less at the poles. The Earth has quite a few square meters, more than 150 trillion if you count only the land. Harvesting a tiny fraction of a percent of this will provide more energy than we would conveivably use.

Can it be done economically?

The simple answer is yes but it takes more than a deep breath to get one's head around the sheer scale of panels nessesary to do the job. Panel prices have fallen below $1 per peak watt but the installed price has remained stubborly above that. All things considered though, we see $1 per watt installed as an achievable target and so will use this figure. The ratio of peak watts to kWhr/year is around 1,000 ro 1,500 depending on location while solar pannels have effective lifespans of the order of 25 years. The cost of solar power in its primary, intermittent form (perfectly OK for the electrolysis of water), on this basis is $0.05 per kWhr. This is around $580 per toe or around $80 per barrel of oil. We know we can afford this because we have had sustained periods in which oil exceeded $100 per barrel. But with oil prices effectively capped by fracking technology to something around the $50 to 60 mark, the carbon free economy is going to struggle to evolve out of market forces alone.

The most daunting part is the land area the nessesary install base would occupy. Each square meter would produce something like 100 to 150 kWhr per year so we would need something like 2 to 3 million square kilometers to do the trick. And the cost? Something like $100 per square meter so $200 to 300 trillion. Currently that upper estimate is 5 times the current total world GDP for a year although it is only 1.25 times the envisiaged world GDP on the basis of 10 billion population with most of the economies developed.

The bargain of the century

These figures are nothing short of shocking. But alas, so is the scale of the challenge we must meet if we are to avert wholesale melting of the ice caps. Giving over 3 million square kilometers is actually cheap. The melting of ice caps will take far more land than this - even on the basis of the best case scenario. The worse case scenario, that of a runaway greenhouse effect, would end life on Earth. And although most scientists are of the view such a process would be arrested nobody can yet prove this view is correct so the runaway greenhouse remains a concern. Notwithstanding such a scenario, we are looking at loosing the ice caps and seeing a rise in sea level of about 70 meters. We will lose most of our major cities and millions of square kilometers of land. If you think all that means is we will calmly pack our bags and take to the hills, think again. We are going to start fighting. And we are not going to stop fighting until the number of people has dropped below what the reduced land masses can support, if then.

Giving over 3 million sq km is cheap and the offer comes with a good discount. We can park most of it in the desert. There the land is cheap because it is useless for growing crops and not much good for anything else. We would be putting it to very good use. So do we give over 3 million sq km of cheap land now or lose many millions of sq km of expensive land and have a major cull starting very posibly, within the lifetimes of today's children? We have been given notice by Mother Nature. Change our ways or face eviction. And if we don't change the balifs won't be the usual burly goons, they are going to be the four horsemen of the apocalyse. Far from being crazy or unthinkable, 3 million square Km of solar panels is without question, the bargain of the century.

Will it happen?

Braodly, we are optimistic it will because it is already well on its way. Last year the global solar install base topped 200GW and of the organizations who issue install base forecasts, few pridict a figure of less than 500GW by 2020. The history of forecasts to date is that all but a handful of outliers have consitantly underestimated actual solar growth by wide margins. We feel they are continuing to underestimate and think the install base will exceed 1TW by 2020 and rise above 20TW by 2030. There is a very strong instinct to extrapolate when making forecasts and this tempers the extent to which any factors which may boost or supress demand are taken into account. The current picture of exponential growth with the install base doubling every four years or so looks optimistic but it ignores who will be making many of the decisions. Solar is a highly scalable enabling technology you can do at home. There is another established technology that fits that description. If you want to know where solar is going look at the uptake history of the Internet and the mobile phone.

Thanks to the investment of billions in research and many tens of billions in subsidies to encourage uptake, solar has reached economies of scale that give it grid parity in many circumstances. At the price of $1 per installed peak watt solar is a competitive grid supplier in most circumstances and thus has the vast and growing market for electricity to explode into. The stage after that is where solar is cheap enough to elctrolyze fuel and compete with oil and gas head on. That needs an installed peak watt price of $0.50. In this report we have constrained ourselves to a prediction of $1 but we leave it to the reader to decide, in the light of the progress to date, how realistic a price of $0.50 might seem.