The Biosphere

The biosphere – the parts of the Earth where living matter exists has an estimated mass of 1.148 ´ 10¹⁹ g [~2000 Gt carbon] with living matter having a mass of 3.6 ´ 10¹⁷ g [65 Gt C] – 3.1% of the total.

Biomass Energy

Biomass energy or bioenergy refers to the use of a range of organic materials as fuels. These are produced by biological processes, and include forest products, agricultural residues, plants, and municipal wastes. In principle, biomass is inexhaustible and renewable, provided that new plant life is grown to replace the ones harvested for energy. Biomass can either be burned to produce heat or electricity, or transformed into liquid fuels such as ethanol, methanol, or biodiesel. Biomass has been the predominant source of fuel since well into the 19^th century, the most common biomass source being wood. Its dominance was progressively replaced by fossil fuels, first coal and then oil and gas during the 19^th and 20^th centuries. Biomass sup­plies only about 11% of the world's primary energy consumption currently.

Biomass as an energy source has many advantages. It is renewable, provides a convenient way of storing energy (e.g., in the form of wood), which is not the case for wind or solar energy, and it can be found in different forms all over the world. It can reduce the energy-dependence on foreign countries. Biomass is also versa­tile as it includes solid fuels such as wood or crop residues, liquid biofuels such as ethanol, and biodiesel, as well as gaseous fuels in the form of biogas or syn-gas. The latter is a variable mixture of CO and H₂ and may be produced in a number of ways. They can be summarized by the general (unbalanced) equation: 

C(coal/coke)/CH₄ + H₂O(steam) ® CO + H₂ + CO₂

From an environmental point of view, biomass is carbon neutral. On the other hand, the conversion of solar energy to biomass is only achieved at an efficiency of around 1%, which is very low even compared to the inefficient conversion of solar energy to electricity with solar cells (in excess of 10%). In order to generate bioenergy on a large scale, vast areas of land are ne­cessary. Also, great care must be taken in choosing crops for energy production, as these should have a high photosynthetic efficiency, grow rapidly, use minimal amounts of fertilizers, herbicides and insecticides, and have limited water needs to minimize energy input into their cultivation. These "energy crops" should also preferably be grown on land not dedicated to food crops in order to avoid compe­tition with food production. The seas can also be used to grow algae, which can be utilized to produce bioenergy, and experimental facil­ities in the United States and Japan have explored this possibility. With the pres­ent technology, a large part of the world's agricultural land would have to be de­voted to energy crops if they were to supply a substantial amount of our energy needs. Even if the use of bioenergy could be cost-effective in certain cases for the production of heat and electricity, it has generally higher costs than conven­tional energy sources. An economical and sustainable large-scale use of this re­source will therefore require technological advances or breakthroughs, especially in the bioengineering field to design suitable high-yield energy crops. In the transportation sector, the production of cellulose-based ethanol and other liquid fuels, particularly methanol through biomass gasification, will allow a higher yield per unit of land. Algae grown in the sea might also eventually extend the scope of bioenergy.

Electricity from Biomass

The cheapest, most used, and simplest way of using biomass to generate energy is to burn it to produce heat, and subsequently steam to operate electricity generators. In these applications, wood, wood waste and municipal solid waste are the most utilized fuels. The average plant has generally a small size (~20 MW) with efficiencies ranging from 15 to 30% for conversion to electricity. The total efficiency can reach 60% with combined power plants which generate electricity and heat. Methane-rich biogas, if captured and col­lected from landfills, can also be used to generate sizeable amounts of energy.

New technologies that are commercially available for converting biomass to electricity include co-firing and gasification. Co-firing power plants use biomass as a supplementary energy source with a conventional fuel, typically coal. Gasifi­cation converts solid biomass through partial oxidation at high temperature into a combustible gas, containing mainly carbon monoxide and hydrogen. The gas pro­duced can then be burned to gen­erate electricity.

The cost of biomass energy varies widely depending on the fuel, its quality, and the technology used. Electricity-generating costs are however generally higher than those for fossil-fueled plants because of lower efficiencies, higher capital and fuel costs. Most estimates for the fuel cost are in a range of US$150 to US$250 per tonne, but this can be much lower in cases where the fuel is a byproduct from some other process.

Liquid Biofuels

Biofuels are liquid fuels produced from biomass feedstock through different chemical or biological processes. Today, biomass is the only available renewable source for producing high-value liquid biofuels such as ethanol or biodiesel. These fuels can offer renewable alternatives to transportation fuels that presently are obtained almost exclusively from oil. Ethanol, the most common biofuel, is produced by fermentation of annually grown crops (sugar cane, maize, grapes, etc.). In this process, starch or carbohydrates (sugars) are decomposed by micro­organisms to produce ethanol:

C₁₂H₂₂O₁₁ (sucrose) + H₂O ® 4C₂H₅OH + 4CO₂

Straight distillation of ethanol from an aqueous mixture can produce at best a liquid containing around 4% of water by mass which is not suitable as a fuel for internal combustion engines. Pure ethanol has a boiling point of 78.3°C. It is obtained from ~95% ethanol by using a ternary azeotrope (i.e. a constant boiling, constant composition mixture with three components.)

A mixture of 7.5% Water (boiling point 100°C), 18.5% Ethanol (boiling point 78.3°C), and 74% Benzene (boiling point 80°C), forms a ternary azeotrope (boiling point 64.9°C), which is a minimum-boiling mixture. Benzene and Ethanol form a binary azeotrope (boiling point 68.2°C), again a minimum-boiling mixture. Thus, when a mixture of 95% aqueous ethanol and benzene is distilled, the ternary azeotrope distills first, followed by the binary azeotrope, and the final fraction (b.p. 78.3°C) is absolute ethanol.

The available energy from the ethanol produced from sucrose is only 3% lower than that which would be produced if the sucrose was burned. Used as a fuel though, ethanol produces only about two thirds of that given by burning octane, the major constituent of petrol/gasoline. The figures are for equal volumes of the two liquids, their densities being 0.789 [ethanol] and 0.699 [octane], so that a mass-by-mass comparison shows that ethanol is only around 60% as good as octane for producing energy when burned.

Ethanol is used extensively in Brazil and the United States as a response to the OPEC oil embargoes and rising petrol prices (but also to subsidize farmers). The production of ethanol from sugar cane in Brazil reached some 15 million cubic metres per year in 2004. The extraordinarily high productivity of sugar cane (up to 80 tonnes of cane per hectare, compared to 10-20 tonnes for most plants cul­tivated under temperate climates), associated with low wages, has contributed to a great extent to the competitiveness of ethanol in Brazil. The amount of ethanol produced annually in Brazil represents only the equivalent of some 7-8 million tonnes of petroleum oil, less than the quantity consumed by the world in a single day.

In the United States, ethanol produced from maize is used in gasohol, a blend of 10% ethanol and 90% petrol, as well as an oxygenated additive in petrol since the early 1980s. However, ethanol is only economically competitive be­cause of a significant tax subsidy (currently US$0.54 per gallon). Growing maize for ethanol production is also very energy-intensive because of the need and cost of fertilizing, harvesting, and transporting the maize, as well as subsequent fer­mentation and distillation which requires large amounts of energy that are gen­erally provided from oil and natural gas. It should be emphasized that, in fact, ethanol produced from maize produces at most only 25-35% more energy than was consumed in its production. Indeed, some claims state that the pro­cess is a net energy user. In any case, maize used for ethanol production is far from an ideal feedstock, though dedicated energy crops and new genetically engineered crops could increase the energy efficiency. Currently, the development of new strains of microorganisms capable of digesting cellulose di­rectly is being explored, and this may allow the use of other types of vegetation with lower production costs to be processed to ethanol, making the overall process cheaper and more efficient.

Biodiesel, processed from seed crops such as rape, sunflower and soy, are currently mainly produced in Europe and the United States on a limited scale. Market penetration is small and the production costs relatively high, although interest is growing. In 2004, biodiesel represented less than 1% of the 270 Mt fuel (petrol and diesel fuel) consumed by road transport in Europe. The direct use of plant oils in diesel engines is not recommended as it considerably reduces engine lifetime. This drawback has been mitigated by reacting these oils with methanol or ethanol in a so-called transesterification process to yield commercial biodiesel. Biodiesel can be blended without major problems with regular diesel oil in any proportion. The production of biodiesel is also less energy-intensive than ethanol from maize because no fermentation and distillation is necessary. However, biodiesel from oil seed crops requires up to five times more land per unit of energy produced than ethanol.

A report in The Daily Telegraph was entitled,

Global warming rage lets global hunger grow

By Ambrose Evans-Pritchard, International Business Editor. Some extracts follow.

We drive, they starve. The mass diversion of the North American grain harvest into ethanol plants for fuel is reaching its political and moral limits.

"The reality is that people are dying already," said Jacques Diouf, of the UN's Food and Agriculture Organization (FAO). "Naturally people won't be sitting dying of starvation, they will react," he said.

The UN says it takes 232kg of corn to fill a 50-litre car tank with ethanol. That is enough to feed a child for a year. Last week, the UN predicted "massacres" unless the biofuel policy is halted.

We are all part of this drama whether we fill up with petrol or ethanol. The substitution effect across global markets makes the two morally identical.

Mr Diouf says world grain stocks have fallen to a quarter-century low of 5m tonnes, rations for eight to 12 weeks. America - the world's food superpower - will divert 18% of its grain output for ethanol this year, chiefly to break dependency on oil imports. It has a 45% biofuel target for maize by 2015.

"The world food situation is very serious: we have seen riots in Egypt, Cameroon, Haiti and Burkina Faso," said Mr Diouf. "There is a risk that this unrest will spread in countries where 50% to 60% of income goes to food," he said.

Haiti's government fell over the weekend following rice and bean riots. Five died.

The global food bill has risen 57% in the last year. Soaring freight rates make it worse. The cost of food "on the table" has jumped by 74% in poor countries that rely on imports, according to the FAO.

Roughly 100m people are tipping over the survival line. The import ratio for grains is: Eritrea (88%), Sierra Leone (85%), Niger (81%), Liberia (75%), Botswana (72%), Haiti (67%), and Bangladesh (65%).

This Malthusian crunch has been building for a long time. We are adding 73 million mouths a year. The global population will grow from 6.5bn to 9.5bn before peaking near mid-century.

Asia's bourgeoisie is switching to an animal-based diet. If they follow the Japanese, protein-intake will rise by nine times. It takes 8.3 grams of maize feed to produce a 1g of beef, or 3.1g for pork.

China's meat demand has risen to 50 kg per capita from 20 kg in 1980, but this has been gradual. The FAO insists that this dietary shift is "not the cause of the sudden food price spike that began in 2005".

Hedge funds played their part in the violent rise in spot prices early this year. To that extent they can be held responsible for the death of African and Asian children. Tougher margin rules on the commodity exchanges might have stopped the racket. Capitalism must police itself, or be policed.

Is there any more land? Yes, in Russia, Ukraine, and Kazakhstan, where acreage planted has fallen 12% since Soviet days. Existing grain yields are 2.4 tonnes per hectare in Ukraine, 1.8 in Russia, and 1.11 in Kazakhstan, compared with 6.39 in the US. Brazil has the world's biggest reserves of "potential arable land" with 483m hectares (it currently cultivates 67m), and Colombia has 62m - both offering biannual harvests.

The catch is obvious. "The idea that you cut down rainforest to actually grow biofuels seems profoundly stupid," said Professor John Beddington, Britain's chief scientific adviser.

Goldman Sachs says the cost of ethanol from maize is $81 a barrel (oil equivalent), with wheat at $145 and soybeans $232. It is built on subsidy. Currently the actual price of a barrel of oil is around US$110.

New technology may open the way for the use of non-edible grain stalks [currently they are burned] to make ethanol, but for now the only biofuel crop that genuinely pays its way is sugar cane ($35). Sugar is carbohydrate: ideal for fuel. Grains contain proteins made of nitrogen: useless for fuel, but vital for people.

Whatever the arguments, politics is intruding. Food export controls have been imposed by Russia, China, India, Vietnam, Argentina, and Serbia. We are disturbingly close to a chain reaction that could shatter our assumptions about food security.

The Philippines - a country with ample foreign reserves of $36bn (Britain has $27bn) - last week had to enlist its embassies to hunt for grain supplies after China withheld shipments. Washington stepped in, pledging "absolutely" to cover Philippine grain needs. A new Cold War is taking shape, around energy and food.

The world intelligentsia has been asleep at the wheel. While we rage over global warming, global hunger has swept in under the radar screen.

Recent correspondence

 

JOINT PRESS RELEASE

by Professor David Bellamy and Mark Duchamp

European Commission cut from reality ?


Three cheers !  At last the peddlers of doom have seen the light : bio-fuels do displace food crops and rain forests !
Starving the poor and destroying biodiversity to give us good conscience as we pour cereal-based ethanol into our tanks is not a smart thing to do. Even Greenpeace admitted it, while avoiding to mention they had much to do with that fiasco. 

But Eurocrats are not as smart : "there is no question for now of suspending the target fixed for bio-fuels," said Barbara Helfferich, spokeswoman for EU Environment Commissioner Stavros Dimas (1).
- In other words, they'd rather cause starvation, and destroy rain forests, than admit they goofed.

Their rationale boggles the mind : "you can't change a political objective without risking a debate on all the other objectives," which could see the EU climate change and energy package disintegrate, an EU official said (1).
- It is all very clear : allowing a debate on public policy is what the European Commission fears most ; more than starvation in poor countries, more than widespread destruction of biodiversity, and more than economic havoc caused by their cherished "climate change" policy.
 
Will we, Europeans, tolerate this neo-stalinist behaviour ? It is not just a matter of bureaucratic arrogance : this time it has become obvious that we are dealing with dangerous lunatics.

The Eurocrats have everything to lose if they stick to their smoking guns any longer. A debate is dearly needed on everything they've been doing wrong, from bio-fuels to carbon trading, and from climate change hysteria to the destruction of peat and designated areas by expensive and redundant windfarms.


(1) http://news.yahoo.com/s/afp/20080414/sc_afp/euunfarmpovertyenergypoliticsbiofuel_080414143918


Co-signed on April 20th 2008 by :

Professor David Bellamy
and Mark Duchamp

A letter from the May edition of the Royal Society of Chemistry News:

 

In a recent RSC press release (March 27, 2008) Richard Pike points out correctly the vast amount of land required to produce biofuels from crops, since the useful energy capture "represents less than 1% of the sunlight absorbed by the Earth's surface".

There is necessarily a conflict between growing crops for fuel and crops for food as arable land is limited. However, growing algae to make biofuel presents potentially a different proposition, and PetroSun, Texas, have just begun production.

According to their figures that 4.4 million gallons (US) of diesel can be produced from 1,100 acres, we may deduce that 32.6 tonnes of diesel plus 116 tonnes of (other) biomass will be produced per hectare per year. Assuming the figure of 174 W m^-2 that Richard Pike uses, this amounts to a photosynthetic efficiency of 4.7%, and is better than crop-based biofuel production by a factor of 10-20.

In addition, there is no necessity to use arable land nor to divert freshwater, since the algae grow well in saline ponds, and could be placed on any land or water. True, algae-to-diesel conversion science is in its early days, but it would be premature to abandon the concept of harvesting sunlight naturally to make liquid fuels.

The gap in supply and demand for oil world-wide is expected to occur by 2015, and hence we need an alternative fuel or strategy very soon, if we are to keep transportation and hence the global economy running.

Chris Rhodes CChem FRSC, Reading