La lune


Documentation > Greenhouse effect > Is there an ideal world ? > Could we live just like today with only renewable energies?
Documentation > Miscellaneous Energy > Energy > Could we live as today with just renewable energy?

Could we live as today with just renewable energy ?

december 2003

website of the author : - contact the author :


Ah, it would be so nice.... done with refineries or pipelines that explode, tankers that spill their oil, climate change, coal mines, nuclear power plants and all the rest : a couple of windmills, a couple of colza fields, and hop ! everybody lives about like today, happy ever after in a world that got rid of its problems. Is it theorically possible to allow us Occidentals to keep a world close to the one we know today with just renewable energies ?

All that follows is based on my personal analysis of the french statistics on energy consumption (if you are curious explanations are here), but the general purpose is probably applicable to any "occidental" country except, maybe, Australia and Canada.


Our energy consumption : what are we talking of, exactely ?

Ask any of your neighbours what "energy savings" means for him (or her), and chances ares that he will quite exclusively mention low concumption light bulbs or efficient windows. Does it mean that most our energy consumption is located in lighting and house heating ?

Breakdown by usage of the primary energy consumption in France (the primary energy is the total energy consumed by the country) in 1999. Source : Observatoire de l'Energie. The total represents roughly 250 Mtoe (Mtoe means million tonnes oil equivalent ; 1 tonne oil equivalent = 11,600 kWh).

Lighting is part of the item "electricity uses, heating excepted".

"use as feedstock" designates hydrocarbons that are not burnt but used as raw material by the chemical industry to manufacture various products (plastics, washing powder...). The percentage corresponding to each use can be seen on the pie chart below.

This broad view enables to see that we actually consume energy through any daily action (traveling, being in a home, but also buying about any product or service), and if heating is not a negligible item, with 20% of the total energy consumption, lighting represents less than 1% of the french total. All the rest corresponds to "something else". Let's see how renewables might - or might not - be a possible susbtitute to the present sources.



I'll be accused of choosing an easy start : I'll begin with the easiest item to "evacuate".

Brzakdown by activity of the energy consumption in industry and agriculture in France. Source : Observatoire de l'Energie. The total represents roughly 80 Mtoe.

From the above graph and data available otherwise, it is possible to draw some first conclusions :

It is producing "basic materials" that requires large amounts of energy : "use as feedstock" (see explanations below), steel production, basic chemical industries, construction materials...absorb much more than half of the industry consumption. Transformation activities are comparatively much sober.

Through eating, buying any object that contains plastic, steel, aluminium, fabric, consumes energy (and on the above graph there isn't the energy used for the transportation of goods, or for the heating of factories and offices). That some materials are "recyclable" doesn't mean in any way that :

it is posssible to recycle them to obtain the same material. If bottle glasss is indeed recycled to produce new bottles, recycled plastic cannot necessarily be used instead of "new" plastic, and the majority of materials that are said to be "recprocessable" are actually unable to be used to produce the same objects than those they come from. For example many metallic residues from incineration are "recycled" to build roads. But increasing the amounts of roads is a "recycling" for which we can discuss the "ecological aspect" !

recycling enables to save large amounts of energy. For example, today, manufacturing new paper from wood or from recycled paper is about even regarding the energy consumption (in other words, using recycled paper does not allow to consume less energy to get some "new" paper, because the necessary processes for recycled paper - like ink removing - are as energy consuming as the processes used when starting from wood). Considering that we can buy plenty of paper without any impact on the environment if we just make the effort to throw it in the right bin is alas an illusion. Actually "recyclable" essentially means "is of some use to someone to make something again", but throwing away "recyclable" materials is always less interesting that managing to avoid to buy them ! (without replacing them by something else, of course).

In the vast inventory shown on the graph, what is the potential for renewables ?

If we can - theoretically - turn to the renewables for electricity production or heating retorts in the industry, renewables cannot substitute fossil fuels as feedstocks with the present production level : it is not easy to replace oil by wood or wind (!) to manufacture plastic. It is certainly possible to transform organic chemistry to use wood as feedstock, for example, but yields will then not allow to envision producing the same volumes than today.

Chemical industries, that supply today a vast amount of products that "incorporate" oil or gas (for example plastics, but also fertilizers or....computers), is therefore not "sustainable" under its present form. By the means of hydrocarrbons, we have accelerated our consumption of about everything, transforming at high speed oil in many other products (tupperware, construction games for kids, car seats and nylon stockings, or.....meat by the means of fertilizers), that renewable sources won't allow to maintain at the same level.

Among all the renewable sources for heat - thermal solar, biomass, geothermals - only geothermals, biomass (the first foundries were fed with wood) and concentration solar offer a ressource concentrated enough to supply a factory in heat. Using geothermals to slowly cool the earth crust (without much harm for us) is, today, a solution on the paper, but the real potential, though probably significant, is not well known. As for biomass, intensively using it instead of coal, oil and gas that feed the industry today might quickly lead to the deforestation of Europe : after the industrial revolution it is coal that saved our forests ; the rise of industry went with an exploitation of wood that was not renewable at all !

Calling massively on concentration solar would require to install factories in deserts : it is not impossible, but we wouldn't live "just as today", because we should also export all the workers there !

Renewables can't do much for steel production, that alone consumes 15% of the energy of industry in France, because it mostly corresponds to the coal which is necessary to reduce iron ore (reduction is the reverse chemical reaction of oxydation : it consists in "removing" oxygen from a coumpound ; here the operation will consist in removing oxygen from the iron oxydes that compose the ore, to obtain iron under the form of cast iron, that is iron mixed with various impurities). There are alternatives solutions on the paper, such as reducing the ore with hydrogen, itself produced from renewables, but here again the quantities that could be obtained would probably not allow to maintain the steel production at its present level. Maybe that concentration solar could enable to produce enough hydrogen, but here again we would have to move all steel factories to deserts, and we will not do it in a week's time !

Hydroelectricity might deliver large powers (up to several GW, that is several billion watts). Hydroelectricity, that produces "on demand", can feed a factory without any problem (that's the reason why aluminium production, very electricity intensive, historically began in french mountain valleys or near the large rivers of Canada or Scandinavian countries, where dams where possible). But the french industry consuming a third of the electricity production, and our dams producing today 15% of the national total, we should double them to ensure a totally renewable supply for the electricity consumed by the french industry. There would be seasonality problems and of course we could not call on this renewable source for any of the other usages examined here.

Wind power can certainly deliver respctable powers when the wind is blowing (several tenths to a couple hundreds MW) but production is intermittent, which makes it impossible to supply industry (that aks for a constant supply) with this sole source as long as mass storage of electricity is not possible.

In short, among the 80 Mtoe consumed by the french industry, only 30 (electricity) could be supplied in a "renewable" form provided we multiplied dams by 3 in France, and a small fraction of heat (50 Mto) could be substituted by wood, geothermals, and solar energy. The fact of not haaving oil or gas as a feedstock any more would lead to a decrease of production that I am not able to quantify, but a division by a factor anywhere between 2 and 10 seems more probable than a 5% decrease.

This resoning is probably duplicable for any "developped" (that is industrialized) country.



This item represents today a fourth of the energy consumption in France, if we include part of the "energy" sector (see the first chart of the page), that corresponds to refineries, these plants producing mostly car fuels. "Saving energy", to come back to the question introducing the present page, therefore also means movinng less !

The options to replace oil - the main energy for mobility - are here :

Biofuels. But a fast calculation shows that the potential of this solution is close to zero (at least in Europe) if we intend to keep the same level of mobility than today.

Renewable electricity, that brings us back to the precedent item, with a significant difference : for "light" transportation means (light motorcycles for example, but not present cars, much too heavy), the amounts required begin to be compatible with the energy delivered by photovoltaic solar, what allows to envision a modest call on decentralized solar energy when panels won't be as energy intensive to manufacture as what they are today (which is probable within a short decade). On the other hand, if the existence of storage device greatly attenuates the intermittence problem for non constant sources (solar and wind power), these device induce an extra energy consumption because....they have to be manufactured (batteries for example), what requires energy and the use of non renewable resources (rares metals among others). In addition, the "storing - unstoring" cycle of a battery has only a yield of 25%, important losses occuring as heat : the need to store electricity hence frequently induces the need to produce much more than what the final consumption will be.

Let's recall that if we replace heat (in the engines) by electricity produced with no heat source (hydroelectricity or wind power), we must reason on the grounds of equivalent final consumption (see explanations on this other page ; for those that are not !).

In conclusion, to substitute oil, we could call on hydroelectricity, solar energy, biomass or wind power, but :

calling only on hydroelectricity implies to multiply by 10 the present dams, to substitute 50 Mtoe (of final energy), not to mention the energy required to manufacture 30 millions electric cars in France (800 million in the world), which would represent anything up to 100 or 200 Mtoe.

calling only on wind power requires to cover 10 to 20% of the country with windmills, because 50 Mtoe of electricity represent roughly 600 TWh of electricity, that is 150% of the present electricity consumption in France. Of course, electric engines are more efficient that gasoline engines, but even with a need lowered to 20 or 30 Mtoe of final electricity we still face figures than are not compatibles with the possibilities of wind power.

In short, even with the better efficiency of electric engines taken into account, the mobility that we have today can't be satisfied with just renewables. A division by anything between 4 and 10 seems more probable than 10% decrease if oil is not here any more. Even a massive call on nuclear energy, given the problems posed by the storage of electricity or hydrogen, would probably not allow the conservation of a level of mobility close to the present one.


Let's eat !

We consume energy through eating ?!? Yes of course, directly through the fuels put in the tractors, and through the "conservation processes" (cooking, freezing, etc). We also consume indirectly energy through the manufacturing of fertilizers, and the fact that each time one buys a "ready-made" or processed food, with a metal, plastic or glass packaging, one "buys" in the same time the energy that has been used to manufacture the packaging.

What can the renewables do here ?

biofuels could be used for the tractors, but it would require the allocation of a significant fraction of the arable land (see details),

For the part of the energy the concerns food processing, we are back to the general discussion on industry (above),

For the indirect part attached to the fertilizers and pesticides, substitutes are :

manure for fertilization, but it would require to reorganize all french agriculture so that each hectare of cultures had a herd abundantly defecating nearby : bye bye specialization of cultures over vast zones !

"basic" pesticides (copper sulfate for examaple) but also natural predators (whose number increases with the amount of appropriate fittings set around : hedges, portions of grass filled land, etc).

The agriculture in a world that only calls on renewables is therefore organic (or not far from it), but delivers much less meat per inhabitant than today.

Meat consumption per person and per year for France, from 1800 to 2000. Source : Bernard Sauvant, INRA. The burst of the meat consumption happens just after the Second World War, when "synthetic" fertilizers and pesticides start spreading, showing that an important meat consumption and an intensive oil dependant agriculture are strongly coupled for the time being.

The "synthetic" fertilizers - manufactured from natural gas or carried from the potash mines thanks to oil - have enabled a burst of yields, sine qua non condition to be able to feed a lot of animals that we will then eat. In a kg of "industrial" beef, there is roughly 3 kg oil equivalent of energy : how many opponents to oil and nuclear consider that anyone is entitled to eat steack without restriction ? The true ecologist is Coffe !



Heating - be it houses or large buildings, the latter referring to plants, offices, or schools - requires roughly 50 Mtoe per year in France, that is a fith of our primary energy consumption. It is probably in this field that the substitution possibilities are the most important :

Wood could be used as fuel (but then forests are not available to produce timber wood, and hence reduce the energy consumption devoted to producing concrete or steel for the construction sector) ; see details here,

Direct use of solar heat is technologically fit, and here also the potential is very important : if it is probably impossible to heat buildings with solar energy only (heat can be stored but not over long periods), a fat 50% of the heating energy can easily be obtained (see details). Let's add that heating energy could itself be divided by 2 in France with a massive energy saving plan for old houses.

And at last it is theoretically still possible to use renewable electricity (such as wind power or hydroelectricity), but we have seen above that 100% renewable electricity is by far less abundant than electricity produced out of coal, gas or nuclear. Once we have used this renewable electricity for industry and transportation, it is not obvious that there would be much left for heating !

Provided we accept to have less timber wood, and pretty less paper, and combination of thermal solar and wood could probably provide the bulk of our energy consumption for heating in France. Still wood is heavy and can be carried only with a non ridiculous energy spending : wood heating is more efficient if the place where it is used is close to the place of production, which means that packing up 80% of the population in large cities that require long distance transportation for supplies kind of "links" to non renewable sources (easy to carry) for this use also.

Still heating is the use of energy for which the possibilities are the most important.


Other energy uses in the houses

We will find here hot sanitary water, cooking, and electricity which is not used for heating and called "specific" (it designates electricity which is used to power a washing machine, a fridge, an elevator or a TV set, and in general for any use for which electricity can't be substituted by gas or fuel oil with present technologies).

The discussion on hot sanitary water (showers, etc) is exactely the same than for heating (see above), beacause it is frequent that heating starts by producing hot water that will be circulated through radiators. As heating sanitary water consumes only a fraction of what we use for heating, renewables can also do much for this use. Actually solar heaters are today the most widely spread devices among those that enable to use renewable energy supplies.

For specific electricity, that represents roughly 30 Mtoe per year in France (that is 15% of our primary energy consumption, using the appropriate conversion factor), the breakdown is as follows :

Electricity consumption in houses and appartements in France in 1999 (Mtoe). Source : Observatoire de l'Energie (Ministère de l'Industrie).

A couple of explanations and commentaries on this chart :

Lighting houses, that is1% of the french energy consumption, is not really a priority for energy savings compared to transportation (consuming less = moving less + using lighter cars), heating (consuming less = decreasing the size of the housing + lowering the temperature), or industry l'industrie (consuming less = buying less manufactured products or services) !

In a house, letting go the cloth dryer (that uses as much energy as the whole lighting when there is one) is worth more than replacing all the "ordinary" light bulbs by low consumption ones,

Doing without a freezer is also a source of important savings : on the first hand the direct consumption is alleviated of so much, and on the second hand it avoids to buy all kinds of frozen foods, well the food processing industry and the freezing process induce significant energy consumptions. In a frozen pizza, there is more oil than ham !

What can our renewables do here ? The corresponding consumption, that is140 TWh in France, could be produced with a fraction of the roofs covered with photovoltaic solar panels (see details of calculation), because we face here low unitary amounts, compatible with a decentralized production such as the one provided by photovoltaïc solar.

But it is necessary to manufacture the panel and the battery, and store the electricity for periods without sun : all this induces significant losses. In addition, all roofs are not turned to the south, so it seems likely that such a way to proceed could only deliver a fraction of the present electricity consumption. For wind power we would also have to manage the problem of intermittence, even if we are able to build 100.000 or 200.000 windmills, but hydroelectricity allows to get over all these inconvenients, provided we are able, in France, to triple the dams just for this item (in house electricity consumption).



It is reasonnable to consider that a world that would call only on renewables would have serious differences with the one we know. Material abundance, that supposes, to start with, a massive production of steel, concrete, etc, is not possible at the level we know - and even not possible at all for some specific materials very hard to obtain without oil - with only these sources. Besides, storage problems for the intermittent modalities, with the associated losses that it represents, the land use required by most sources, and the limitations inherent to the laws of physics (nobody will change the kinetic energy of a moving mass of air) result in the fact that our present world - where abundant energy is omnipresent - can't be sustained with just renewables, and by large. From there, is it wise to render our world a little more dependant on non renewable resources every day ?

Let's add the trying to convert to renewable energies all that could be would lead to a land use that many "ecologists" would probably not like : it would be necessary to cover almost all France of dams, forests intensively grown for wood fire (with a low biodiversity), windmills, and crops for biofuels. Does such a picture correspond to a "clean" develoment ?

It is likely that, except if we set up a massive program of breeders (but 40 years are necessary to complete such a prograam : in no way can nuclear energy be used as a "spare wheel" to quickly replace fossil fuels the day we are anguished by soon to come shortages or bythe possible consequences of climate change), the energy abundance will end with the depletion of the fossil fuels, renewable energies being totally unable to replace fossil fuels at the present level of consumption, even if, of course, thay have a place on the future supplies.

Even calling on nuclear will not allow to keep the present organization of occidental societies, as electricity is not able to substitute oil as a raw material in the present world. The first thing to do, if we want to be prudent, is to enage in a division of the energy consumption by 2 or 3, and not to increase it "as soon as everything is fine", thinking that renewables will be able to take on the day it is needed.


Back to the index
Back to the top