Let’s face it: energy efficiency is boring when compared to the (relative) excitement of developing new sources of low-carbon electricity or heat. The popular science magazines are full of articles on new forms of solar panel and the latest designs for wind turbines. Improving the insulation of ordinary homes, shifting to LED lighting or increasing the take-up of heat pumps rarely command the attention of editors.

***

In a breathtakingly elegant paper in Energy Policy, Jonathan Cullen and Julian Allwood of Cambridge University try to persuade us just how wrong we all are.[1] The theme of the paper is that carbon emissions are far more responsive to changes in how we use energy than in how we generate it. They say that it will be cheaper, easier and quicker to make efficiency savings than to switch to renewable electricity or heat.[2] The scale of the loss from the raw energy value of a fossil fuel to its eventual productive use is enormous and the authors argue that cutting this gap is a far easier task than replacing the 50,000 fossil fuel power stations with millions of wind turbines and vast solar power plants strung across deserts to meet our emissions reductions estimates. Are they right? This article uses the Cullen/Allwood paper to look at the total potential saving that might reasonably be obtained in the next couple of decades if we make a determined effort to improve energy efficiency.

My very tentative conclusion is that we can look for a 40% reduction in current energy use if we pursue efficiency objectives enthusiastically. (I don’t look at the impact of economic growth in developing countries and the way this might substantially increase total energy demand.) Perhaps surprisingly, the cost of achieving even a 40% energy efficiency gain looks high to me, particularly compared to the cost of decarbonising electricity generation. Wind turbines probably give a better return on investment.

The background data for the Cullen/Allwood paper is not complex or controversial. The world uses about 475 exajoules a year, all but 100 of which are from fossil sources. Their contribution comes from rigorous quantification of how these energy sources are turned into things that we actually desire. First, the primary sources of useful energy are processed – usually burnt – in a variety of machines, such as a diesel engine or an oil burner. The eventual result is motion, steam, useful heat or cool, and the transformation of materials (turning ore into metal, for example). These things then deliver what human beings want – personal transport, a comfortable home, the ability to communicate, clothes and food.

What is an exajoule?
A exajoule is a unit of energy. Therefore it can be converted into, for example, kilowatt hours, which is another way of describing an amount of energy. To be a really useful measure, an exajoule will usually need to be expressed as a number for a particular period of time such ‘exajoules per year’.

475 exajoules, the world’s yearly use of energy from primary sources such as coal and oil, roughly translates into a continuous power use of about 5.5 terawatts. To put this figure into context, this is about 120 times the average electricity demand on the UK power grid. 5.5 terawatts spread over the world’s population is about 2 continuous kilowatts a head, or about 17,000 kilowatt hours a year. For comparison, the UK continuous power usage is about 5 kilowatts a head – two and a half times as much – and therefore approximately 42,000 kilowatt hours a year.

The paper sets up a four-stage chain. Fuels are extracted or, in the case of renewables, collected and then converted in a machine that turns them into heat or other useful energy source. The process occurs in what the authors call a ‘passive system’ such as a vehicle or a hot water system. The final service is something directly desired by the individual consumer or business, such as transport or comfort. There are efficiency losses in this stage in the chain.

The paper estimates the volumes of energy being used by the world’s major energy conversion devices. The top six machines are as follows:

Table 1

These machines are directed towards producing about 233 exajoules of heat a year and about 175 exajoules of motion. The energy for motion will be accompanied by heat. For example, a car’s petrol engine produces far more heat than energy for motion. So, in the case of a diesel engine, the world’s most important energy conversion device, only about 25% of the chemical energy in the fuel gets turned into energy to move the car.

The service provided by the energy can then be described. Table 2 shows the useful things we get from the 475 exajoules each year.

Table 2

Let’s look each output in turn. How much can we expect to be able to save through well-understood energy efficiency options? (Almost all of the figures in the following section are my estimates and are not from the Cullen/Allwood paper.)

Thermal comfort
Few buildings anywhere in the world are particularly well insulated. The typical British home loses around 250 watts per degree Celsius of temperature difference between the outside and the inside of the house. This means an average input of heat of around 200 kilowatt hours a year per square metre of space, compared to best practice (Passivhaus) levels of less than a tenth of this figure. Say, as a simple approximation, that we tried to get UK housing down to a level of 100 kilowatt hours per square metre. This would be expensive and unpopular since it would need most brick-built houses to be clad with insulation materials. If this 50% cut was replicated elsewhere, and also applied to building cooling needs (and there is no reason why not), world energy demand would be cut by approximately 10% (19% times 50%).

Other major energy-use savings could be generated by large-scale switching to heat pumps for home and business heating. We could, in theory, push the energy needed for thermal comfort down very dramatically, but the changes to buildings and their heating systems would have to be enormous. So I have used an estimate of a 50 exajoules energy efficiency saving.

Potential saving from better efficiency: 50 exajoules?

Sustenance
The average person needs about 2 kilowatt hours in food energy a day. (When talking about food, this 2 kilowatts is usually expressed as approximately 2,000-2,500 kilocalories.) The energy efficiency of food varies dramatically by type of product. Red meat might be 10% efficient (i.e. ten units of external energy are needed to produce one unit of food energy) whereas a grain such as oats, which is not generally heavily fertilised, might be as high as 500% (one unit of fossil fuel energy produces five units of food energy – most of the food energy comes from photosynthesis). About a quarter of the calories in the US diet come from meat and dairy products and a similar fraction in most of northern Europe.[3] If this figure fell to about one eighth, or if we switched from the least energy efficient meat (beef) to the best (chicken), the savings could be 40% of total energy consumption. Of course, a wholly vegan diet would increase these numbers hugely, but I haven’t assumed this.

Potential saving from better efficiency: 40 exajoules?

Structure
The key improvements here are weight reduction in the structural materials and a move to ‘closed loop’ recycling. For example, creating metals from ore is generally an extremely energy-expensive process. Think of making aluminium from bauxite, for example. Once we have created a metal from ore, there is usually no good reason ever to dispose of it. But dispose of it we do. 50% of aluminium cans go into landfill in the UK. Even valuable metals such as silver, widely used in very small quantities in electronic devices, disappear as your mobile phone is tossed into the waste.

Almost everything can be reused several times and sometimes indefinitely; but almost nothing is. And as the world becomes virtual, physical structures (such as paper) can be replaced by digits or by transient appearance on a screen.

The Cullen/Allwood paper also mentions the importance of such things as the streamlining of cars, another way in which structural changes can reduce the total need for energy.

Potential saving from better efficiency (this is even more of a guess than other estimates): 30 exajoules?

Freight transport
Freight transport is likely to remain as a major customer for fossil fuel suppliers for many decades. The diesel engine is only 25% or so efficient at turning the chemical energy into energy for motion, but only a huge rise in the price of oil is likely to prompt a switch to electric vehicles or electrically propelled railway trains. Diesel itself may be replaced by biologically derived oils, made from oil seeds or even algae. Whether these bio-oils can be described as more energy efficient in the language of the Cullen/Allwood paper is not clear. These forms of diesel are replacing fossil fuels with photosynthesis processes but the underlying efficiency of the engine remains the same.

In the medium term, it may be possible to switch diesel transportation to vehicles powered by hydrogen fuel cells. This would save energy since a fuel cell may offer twice the conversion efficiency of a diesel engine. Only half the energy is needed for the same amount of transportation

Potential saving from better efficiency: 10 exajoules?

Passenger transport
Passenger cars may switch to electricity and to hybrid electricity/fossil fuel. Both routes offer very substantial savings. Electric cars have approximately 80% conversion efficiencies (chemical energy to energy usable for motion) compared to 20% or so for petrol vehicles. This latter figure is rising quite fast as a result of innovations in materials, drive trains, aerodynamics, and other parts of the car. So a move to a car fleet that is battery equipped, possibly combined with a hydrogen fuel cell, may offer very substantial energy efficiency savings. Greater use of electricity for long-distance transport by rail and employment of fuel cells for urban buses will also help. But nothing in sight will reduce aviation’s energy use per passenger kilometre by as much as the use of electricity for cars.

Potential saving from better efficiency: 30 exajoules?

Hygiene
The appliances of motors can be made more efficient but the heating of the water is now the dominant use of energy in ‘wet’ domestic appliances. And, unfortunately, the energy used to heat a litre of water through ten degrees is always going to be the same. It’s certainly true that washing machines, for example, can be programmed to run at lower temperatures and use less water, but the remaining savings above and beyond what is already achieved are probably not enormous.

The amount of hot water for bathing may be possible to reduce by the use of water-saving showers, but the savings are probably not substantial.

Potential saving from better efficiency: 15 exajoules?

Communication
It’s not clear to me that large reductions in energy use are possible. As countries develop, they are also likely to devote a large fraction of their incremental national income to this category so total energy demand may rise, though this is not relevant to our estimate.

Potential saving from better efficiency: 10 exajoules?

Illumination
In most countries of the world illumination comes by the burning of fats and oils. Only in rich countries does a reasonable fraction of fossil fuel energy get employed in providing lighting. In these places, the switch away from incandescent bulbs to more advanced light sources is moving rapidly. A compact fluorescent in the home will typically be four times as energy efficient as the older technology (in terms of lumens per watt of electric power). LED bulbs, just now beginning to come into use, may introduce another four-fold improvement in efficiency. LEDs are also useful in many non-domestic applications such as street lighting, car headlights, and traffic lights.

The scope for a large percentage change in energy use is high, but the absolute amount of the saving in energy is not as large as, say, thermal comfort.

Potential saving from better efficiency: 10 exajoules?

Summing up the estimates
My highly tentative estimates suggest an approximate attainable saving of about 205 exajoules out of the annual global figure of 475. This is a saving of around 40% of current energy use. Let’s call the reduction 2.5 terawatts of continuous power

How much would it cost to achieve the same reduction in fossil fuel use by decarbonising our electricity use? The same net effect as saving 205 exajoules by energy efficiency would be provided by building about 2,000 nuclear power stations or about 2.5 million commercial-scale wind turbines. The cost of 2,000 nuclear power stations might be about £10,000bn ($16,000bn) or about £10,000 per person if divided among the richest one billion people on the planet. Wind might be about the same or even slightly cheaper if we could put most of the turbines onshore or in shallow and calm waters.

£10,000 per person is a large sum, even spread over 10 years. But it is probably less than the cost of achieving the energy efficiency gains mooted in this article. Take housing insulation, for example. Simple savings from wall insulation might only cost £1,000 or so, but generally wouldn’t achieve the 50% cuts in energy use I suggested might be possible in the section above. Really deep cuts in the energy that we use to keep ourselves warm might cost an order of magnitude more. So I want to suggest that even though some energy efficiency savings are cheap – and may even have a quick financial payback at current energy prices – the argument that ‘efficiency’ is always the cheapest way to reduce emissions is not obviously true. Beyond the easy savings from getting rid of gross inefficiency, investment in low-carbon energy sources may be a cheaper way forward.


Footnotes
[1] Jonathan Cullen and Julian Allwood, ‘The efficient use of energy: Tracing the global flow of energy from fuel to service’, Energy Policy, 38.1, pp. 75-81.
[2] Two newspapers for which I occasionally write have now banned the phrase ‘low-hanging fruit’. So I don’t use it in the text even though any article on energy efficiency normally has to use it in the first two paragraphs.
[3] Most of the figures in this paragraph are from Gidon Eshel and Pamela Martin, ‘Diet, Energy and Global Warming’, Earth Interactions, 10 (March 2006), pp. 1-17.

The Maldives. Image source: Primetravels.com.

The Maldives will be the first country to be overwhelmed by the effect of climate change. The republic is a collection of coral atolls with maximum heights of one or two metres above sea level. Climate change is increasing worldwide sea levels and the atolls will probably go underwater by the end of the century.

The 300,000-400,000 people who live on the Maldives are not responsible for global warming. Their emissions per head (even including aviation fuels for incoming international tourism) are less than a seventh of typical European levels.

Many countries have set ambitious targets for the reduction of carbon emissions. The government of the Maldives seeks to encourage this trend by going one step further with a plan for near carbon neutrality within ten years.

This is an immensely challenging target. Chris Goodall (author of this blog) and Mark Lynas, the prize-winning climate change author, were asked to provide a short outline of how it might be achieved and what it might cost.[1]

In the rest of this note, we show our calculations. We will be the first to acknowledge that this work is incomplete. Although it was tempting to conduct fieldwork in some of the most attractive island resorts, we did our analysis using publicly available information and with help from officials attached to the Maldives government.

Our work shows that near neutrality is possible, but expensive. It will take at least $1.1bn for this small island state. The Maldives imports almost all its fuels in the form of refined oil products. Rates of financial return to the investment therefore depend largely on the price of oil. If expectations of future oil prices exceed $100 a barrel, we judge that the plan is sufficiently attractive to be financeable by international institutions such as the World Bank.

Comments on this work will be very gratefully received.

***

The Maldives’ use of fossil fuel
The state has no natural resources other than fish and some of the finest locations for luxury resorts in the world. Fuels, almost entirely in the form of refined oil products, are all imported. There are two principal uses for these fuels – aviation and electricity generation. Smaller amounts are consumed as petrol for cars, diesel for boats, and kerosene for cooking stoves.

The CIA yearly factbook estimates that daily imports of oil products are equivalent to about 5,490 barrels. Although the energy value of oil products varies, this work has assumed that the fuels all provide about 1,700 kilowatt hours of energy. (Please note that the processes of conversion of fossil fuels to electricity are never 100% efficient, so the usable power delivered to consumers will be much less than the energy value of the oil.)

Small volumes of other refined products such as lubricants and bitumen are also imported. Our assessment of the disposition of oil imports is shown in the following diagram.

The Maldives
The country consists of a large number of small islands grouped into atolls. About 250 islands are inhabited. The resident population, including migrant workers, is about 360,000. 600,000 international tourists visit these beautiful islands every year. They are principally from the UK, Italy, Japan, and other remote countries.

About a third of the resident population lives in Male, the country’s capital. Some of the most important tourist islands are close to Male, while others are some distance away. The Maldives chain is 750 kilometres from north to south.

The resorts are provisioned largely by imports. Fish are caught locally and some fruit is grown but the majority of the food provided for the visitors and the resident population is flown in from India, Sri Lanka, and other places.

The majority of the Maldivian population has access to electricity. This power is generally provided by diesel generators operating on the islands and at the resorts.

An outline of our plan
The core of our scheme is:

• the replacement of fossil fuels for electricity generation, for cooking and for some transport
• the purchase and cancellation of EU emissions trading certificates to offset the importation of aviation fuel and small amounts of other fuels that cannot be otherwise be replaced.

Electricity generation
Reliable figures for the amount of electricity generated were not possible to find. Much electricity is generated at resorts and other points on the island by smaller generators and the output may not be measured.

We have estimated that over half the oil imported into the island is used for electricity. The electricity is used for homes and businesses and for the desalination of water. Smaller amounts are used for boats and other uses.

We believe that the total annual amount of electricity generated and consumed is about 540,000 mWh. As the Maldives economy grows, this figure will rise. We are also proposing that the country should gradually switch to the use of electricity for road and some sea transport and for cooking. (The climate of the islands means that no heating is ever required and air conditioning needs are currently quite limited.)

Our estimate of the current needs for electricity:[2]

Our proposal is to replace diesel use with a mixture of:

• wind energy
• solar PV
• biomass combustion in Male
• battery storage outside Male.

Large expenditures will also need to be made on electricity transmission networks.

Wind
Average wind speeds in the Maldives are reasonably high and quite consistent. Apart from the months of April and May, typical speeds are about 5 metres per second. (This compares with figures for central England of about 4.5 m/s.)

Average wind speeds in April and May are somewhat lower, at about 4 metres per second.

Our plan is to install enough wind turbines around the main islands to provide an expected annual electricity output of about 650,000 mWh. This exceeds the annual national requirements for electricity but because the wind does not blow at the same speed all the time, we will need additional generating capacity and electricity storage in reserve.

Our main assumptions are:

Most of the inhabited islands will be using wind power for the bulk of their electricity. In later paragraphs we will look at the need for storage of electricity to cover periods when the wind is not blowing strongly enough.

We have projected a typical cost of about $1,500 per installed kilowatt. Construction costs are likely to be moderate because of the ease of installing foundations in what we are told is coral limestone and sandstone.

Solar PV
The Maldives are close to the equator and receive high levels of insolation. We can rely on good output from solar PV, both as a supplement to wind power and as a source of electricity on islands far from wind turbines.

After taking advice from the Maldives, we assume that the best location for solar PV will be in the very shallow lagoons in the centre of the atolls. Farms of PV panels can be installed at reasonable cost at the edge of these lagoons.

Our main assumptions are stated below:

These panels supplement the power provided by wind. Each location outside Male will need some form of electricity storage.

We have been told that solar energy levels are reliable across the Maldives islands. Monsoon weather produces cloud, but there are very few days without any direct sun. Even in cloud, the Maldives are sufficiently close to the equator for modern PV panels to capture large amounts of solar energy.

We assume a full cost (including cabling and inverters) of about $550 per square metre of installed capacity. This is lower than current levels because of the expected continuing decline in solar panel prices and because of the large size of the typical installation.

The average day length does not vary much in the Maldives across the seasons. But to be useful solar installations will need to be accompanied by some form of electricity storage.

Biomass
A large fraction of the population lives in Male and nearby islands. For these areas, it makes sense to invest in a biomass combustion plant to provide backup when wind is not blowing and insufficient resources of sun are available.

We suggest a 50 mW plant, probably burning biomass wastes, such as coconut husks, some of which can be obtained locally and the remainder from Sri Lanka. We assume that the plant will provide an average output of about 20 mW. On an annual basis this equates to a production of 175,000 mWh, supplementing the electricity from wind and solar. We expect the cost of this plant to be about $50m, including installation. The cost of the biomass is expected to be about $20 a tonne and combustion efficiency about 35%. This implies an annual cost of about $5m.

Storage
We have budgeted for electricity storage equivalent to twelve hours’ typical use in the areas outside Male. (In Male, the backup is provided by the biomass plant.) We exclude desalination because these plants can cope with limited intermittency.

We propose to use lithium iron phosphate batteries similar to those used in the most recent electric cars, although several other electricity storage technologies are possible. Lithium ion batteries are reliable, have long lives, and are completely safe. However, they are expensive. Our total requirement for storage is about 630 mWh and we believe that this will cost $315m. (This is cheaper than current prices for small orders but we have obtained an estimate of target costs in the next few years from Valence, the world’s largest manufacturer of automotive power batteries.)

Each wind and solar installation will need backup power from the battery systems. Further research could demonstrate that other forms of energy storage, such as compressed air, might provide cheaper alternatives, and we would be interested in hearing details of such systems.

Electricity transmission
We have budgeted $100m for improvements in electricity transmission. We are told that the major population centres in the Maldives have electricity networks but a plan to switch to renewable sources will mean a need for new power distribution systems and for controls that maintain the voltage and frequency of AC distribution. Electricity will have to be taken from wind turbines and PV panel systems to local users. Our estimate is inevitably tentative but seems appropriately conservative at about $800-$1,000 per household.

Summary of renewable electricity generation, storage, and transmission
Our projections show the Maldives installing total renewable electricity generating capacity well in excess of total current need. This is partly to provide a margin of safety but also to meet increasing need for electricity supply for uses such as transportation. In addition, the majority of the existing diesel generators will be available to users in the event of temporary unavailability of electricity from the renewable sources.

The available electricity supply in this plan is almost twice the level of current need. This leaves substantial reserve for other uses, such as road transport and cooking, increased desalination, and widening the availability of electricity.

Other uses for diesel
We estimate that about 500 barrels a day of diesel are employed in other uses such as fuel for larger boats. This figure is tentative. In some circumstances, the fuel can be replaced by electricity. In other applications we will need to find alternatives which provide a low carbon liquid fuel. The best option at the moment which does not to involve the use of land that is used for growing food is jatropha oil, made from berries of a tropical shrub that grows on marginal land in places such as India. This is a temporary solution since all biofuels inevitably increase the pressure on the world’s productive lands. In the longer run, almost all diesel uses in the Maldives can be replaced by electricity.

Petrol/Gasoline
About 490 barrels a day of petrol are used in the Maldives for cars and for smaller craft such as the tourist speedboats used in water sports. Over the next decade, the worldwide process of replacing internal combustion engine vehicles with electric cars will move rapidly. Already we are seeing rapid innovation in batteries from companies such as Valence. Every major auto-maker in the world has announced plans to produce electrically propelled cars. The short distances and small number of roads make the Maldives an appropriate location for using battery-powered vehicles.

Batteries need to be charged. This can be done from any mains socket, but as part of this plan for carbon neutrality, we anticipate that the government will need to establish charging points around the main towns that allow vehicle owners to top up their batteries. Renewable energy is an effective way to supply electricity to batteries. Batteries can be recharged when power is abundant, such as during night-time gales, rather than at periods of maximum electricity use. Battery-using cars can thus help to balance demand and supply for electricity. A rapid switch to electric vehicles might therefore help reduce the high cost of electricity storage.

Not all cars can be replaced in the ten years of this plan. Some vehicles will still be using petrol by 2020, as will many boats. We anticipate catering for the demand for liquid fuels by using ethanol from Brazil or other low-carbon sources. (Brazilian ethanol is low-carbon because it is made from sugar cane. The sugar in the cane can easily be fermented into ethanol. The waste from the cane (bagasse) can be used to provide the heat needed for the process. Most studies describe Brazilian sugar cane ethanol as extremely low-carbon because of the ease of making the fuel from ingredients that have absorbed CO2 from the atmosphere. The debate about whether cultivating sugar for ethanol increases the pressure on the world’s limited resources of arable land will continue and we cannot avoid some scepticism about whether ethanol will ever be truly low-carbon. New technologies (usually known as ‘second-generation biofuels’) are likely to use agricultural wastes, such as otherwise unused tree branches and straw, and these biofuels will probably be able to claim very low-carbon status.)

Battery cars vary in price but will eventually be cheaper than petrol equivalents. Electricity will almost certainly be far cheaper than petrol for fuel. A push towards using only electric cars on the Maldives will reduce costs. We have not included this in our estimates in the summary section.

Kerosene – cooking
People on the islands largely use wood or kerosene for cooking fuel. For those homes and businesses using wood or other biomass for cooking, we suggest the introduction of new and highly efficient closed stoves. These stoves burn much smaller amounts of fuel than older types. This reduces the demand for fuel and decreases the pressure on local stores of wood. Homes and tourist hotels within the reach of the electricity system will need to have their stoves replaced with electric equivalents.

We are unable to estimate accurately the number of new stoves needed outside the Male area. A reasonable guess might be about 40,000. At a typical cost of $100 for simple stoves or electric rings, we believe the total bill will be about $4m.

Kerosene – aviation
After electricity generation, the most important source of carbon emissions on the Maldives is aviation fuel. We believe it is approximately 1,800 barrels of oil a day. To be clear, this amount of jet kerosene is not sufficient to provide fuel for the whole of the return journeys of all the international flights coming into Male airport. (In recent days, our check shows that about 8 long distance flights arrive in the Maldives every day.) Most aircraft seem to travel through Colombo, Sri Lanka and may be fully refuelled there, either on the outbound or incoming legs of the return flight.

Although the oil of the jatropha bush may provide a long-term replacement for kerosene, airlines have no current alternative to using fossil fuels. The Maldives economy is reliant on tourism so the country will need to continue to import aviation fuel.

Our proposal is therefore to offset the CO2 emissions from aviation by purchasing emissions certificates from the EU trading system. EU countries have all been allocated a restricted number of allowances (or ‘permits to pollute’). These allowances are traded on a number of exchanges in Europe. The buying and selling of carbon allowances set the price for carbon dioxide emissions in Europe.

By buying and then cancelling emissions permits, the Maldives is decreasing the total volume of emissions allowed in Europe. Its purchases will therefore slightly raise the equilibrium price for CO2 in Europe from its currently depressed level of about €10-€12 per tonne. Raising the price in the EU permit system is important because it increases the incentives on the major polluters, such as power stations, to use lower-carbon technologies.

We need to offset about 270,000 tonnes of CO2 per year to cover the emissions from aviation kerosene landed on the islands. The current cost of this is about $4m but the price varies daily.

We also propose that the Maldives offset any remaining emissions, such as those that arise when diesel generators have to be used because of the lack of wind and sun in the areas that cannot be powered by the Male biomass combustion plant. We propose allocating a total annual cost of $3m for this purpose, making a total offset cost of about $7m.

Methane emissions
Small quantities of methane (a potent global warming gas) are emitted from landfilled organic waste on the Maldives. Methane is given off when carbon-based molecules rot in the absence of the oxygen in air. One estimate suggests that the effect of this might be equivalent to about 20% of the total CO2 output of the islands.

We believe that the best way to avoid these methane emissions is probably to separate organic materials (food, other waste vegetable matter, woody materials) from other forms of waste, such as plastics and metal. The organic material should then be carefully composted and then added to the very thin local soils as a conditioner. With appropriate additions of fertility-raising compounds, this will increase the ability of the Maldives to grow food for its rapidly increasing population.

We estimate the cost of widespread installation of simple composting equipment to be about $6m. (There are about 250 inhabited islands. Composting equipment on 100 of the largest, at a price per unit of $50,000, would cost $5m. The main unit in Male might be an extra $1m.)

A summary of the costs and savings
We assume that all fuel and energy prices remain the same. So, for example, if electricity is priced at 20 US cents per kilowatt hour, the price will stay at this level. The financial effect of the carbon neutrality plan will therefore arise from:

• the equipment needed to decarbonise electricity generation – e.g. wind turbines
• the extra cost of lower-carbon products such cooking stoves. These can also be regarded as capital costs
• the annual cost of offsetting the emissions from imported aviation fuel
• the reduction in the oil import bill, a continuing benefit to the islands. We have assumed that the import cost of refined oil products, including the cost of transport to the islands, adds $10 a barrel to the standard cost of crude oil, which is currently trading at about $45.

Yearly costs and savings

Savings – two scenarios

What can we take from this financial analysis? If oil prices remain at $45 a barrel ($55 for refined products) then the costs of carbon neutrality are high and would not easily meet the standard tests of financial viability. For a country with a GDP of less than £2bn, the bills are large. But at $110 for a barrel of refined products the gains from reducing the use of fossil fuel are great enough to make the proposals financially attractive.

Crucial to the plan is the near-complete decarbonisation of electricity generation over a period of about 10 years. This will be the single most important switch in other countries as well, although it will take far longer in countries like Britain.

(This material accompanies Duncan Clark’s article ‘Maldives first to go carbon neutral’ in the Observer on Sunday 15 March 2009.)



Footnotes
[1] Mark Lynas and Chris Goodall will receive no payment of any form for this work.
[2] These estimates are necessarily imprecise. But they are unlikely to underestimate current electricity use because otherwise electricity production would use an implausibly large fraction of total diesel imports.
[3] This is about 0.15% of UK electricity production, and approximately a third of the figure per head in the UK.
[4] This assumes a small continuing improvement in typical efficiency for standard silicon panels. The Maldives could decide to invest in lower efficiency thin film panels which are considerably cheaper.

Photograph: Christopher Whalen.

George Monbiot rightly observes that the earth’s resources of biomass are limited and cannot be simultaneously claimed for multiple uses: liquid biofuels, fuel for heating, biogas, and biochar. This presentation (available for download in PowerPoint or PDF) looks at the globe’s land and biomass production to assess how much space can be given over to non-food uses and how much energy this can generate. This is one of the crucial questions facing the world: how much energy can we use from biomass before this affects the ability of the world to provide enough food for nearly 7bn people, rising to at least 9bn by 2050?

Ten Technologies to Save the Planet was listed as one of the Financial Times Science Books of the Year 2008.