Intact Harvester

These days it seems you can’t turn on the TV or read a newspaper without being confronted with yet another news item about the problem of climate change. Again and again we hear about how CO² levels are and average temperatures are rising, how the icecaps are melting, and how weather is becoming more extreme. We know it’s all caused by using gas and oil too fast, but the one thing we don’t hear a lot about is acceptable solutions. By acceptable, I mean ways that will not adversely effect our standard of living.

Until now, that is. What follows is a description of a new invention that will reduce our reliance on fossil fuels (and so help to address the problems of climate change) without using agricultural land to grow crops for fuel. Even more importantly this idea will go someway towards feeding the expected 8 billion world population in 2025 at the moment of Peak Food as biofuels can be produced without using the food portion of the crop.

The Intact Harvester 

The Intact Harvester 

The diagram above shows a machine that would replace the combine harvester and after swathing or spraying with roundup to reduce moisture content, harvest cereals intact i.e. harvest the grain and the straw. The straw and grain would be sent together to local processing plants where they would both be processed. The straw (which often contains almost the same amount of energy as the grain) would be used to make electricity or cellulosic ethenol. In the case of oilseed rape, the seed would be crushed for vegetable oil and the residue used to feed livestock. For cereals, the grain would be used for food and any further drying required would use waste heat from the burning of the straw instead of oil.

Advantages

Thus the advantage of this machine would be:

  •  a far higher energy balance than present, as shown below:

Intact Harvester Energy Balance

 

 

Conventional Harvester Energy Balance

  • the amount of energy produced on every acre would almost double while at the same time the energy input required to harvest, dry and store the crop would be reduced
  • weed seed return would reduce as more of the seed would reach the local processing plants millings (weed seeds plus small light or broken grains) would be used which studies in Canada has shown make a valuable animal feed.
  • there would be better utilisation of expensive machinery as the local processing plant would run all year around as opposed to hundreds of expensive combine harvesters that would only do seasonal work
  • So we would use less fossil fuels for higher energy output, thus partly addressing the issues of climate change and food production.


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How Intact Harvesting can become a Reality

Make no mistake, a move to intact farming in the West would be a major undertaking. It would require Western governments to back the initiative by:

  • funding the development and large scale commercialisation of celluosic ethenol production
  • funding research into intact whole crop harvesting and total crop utilization at crop processing plants or bio-refineries
  • taxing carbon to stimulate rapid innovation in every industry from agriculture to heavy engineering

What can we do as individuals?

Using low energy lightbulbs and turning unnecessary appliances off is a drop in the ocean compared with what needs to be done. The best thing you can do as an individual is to petition Hilary Benn,  Secretary of State for Environment, Food and Rural Affairs.  If you wish to do this, click here  for contact information.  Alternatively send an email to BennH@parliament.uk

Further Background Information

Many years ago, Marion King Hubbert said, “We have to steer ourselves into a stable state with as little catastrophe as possible.  We should be looking for other sources of energy.  There’s only one big enough.  It’s free and it’s good for at least a billion years.  That’s the sun.”

The sentiment, especially coming from an oilman, is well worth remembering.  After all, there are those with vested interests who will always seek to promote the energy source that brings them most personal advantage or satisfaction.   
If it were not for climate change caused by GHGs, the gap caused by oil depletion could be filled by deposits such as bitumin in Venezuela, oil shale in various parts of the U.S. and tar sands in Alberta.   Unfortunately massive amounts of water and energy are needed to exploit them.  The tar sands, for example, have to be dug and then steamed before final refining.  The natural gas burned in the process would emit CO² as would the fuel itself as it was burned. There would also be damage to the landscape and pollution to groundwater.

So use of these ‘unconventional oils’ on a large scale is not an option.  Fortunately they aren’t needed.  As Hubbert pointed out, the sun is a gigantic source of energy and good for at least a billion years.    Each day there are many hundreds of times more solar energy coming to Earth than we need. 
And there are no problems that can’t be overcome!  In the past fossil fuel has been so cheap and plentiful that solar energy has been expensive by comparison, whether it be collected via plant leaves through photosynthesis, through wind or water turbines, by wave, photo voltaic cells or solar panels.   However, since fossil energy prices have increased recently, the gap in costs has narrowed and changes to the tax system would tip the balance in favour of renewables causing rapid technological advances in methods of collection and storage.

Again due to the availability of cheap fossil fuels, we have never needed to be efficient in collecting solar energy.  We have not made as much use of photosynthesis (the process whereby plants utilise light energy from the sun to convert carbon dioxide and water to carbohydrate material) as we could have.

Photosynthesis and the methods by which it is utilised have always been crucial to the survival of mankind.  Now it is even more so, as we return  to a time when it will be used to produce fuel to power farming and so provide us with food.
Luckily we have learned many valuable lessons in the age of oil. For example, powering farm machines with biodiesel uses much less land than feeding workhorses to do the same work.  The availability of cheap fossil fuel has also meant that we have not had to worry about the energy balance i.e. the amount of energy consumed growing, harvesting, drying and storing crops compared to the energy produced.  We therefore have been able to adopt a system which is highly efficient in the use of manpower but which consumes large amounts of fossil energy and wastes even larger amounts of renewable energy. As an example, shown later in detail, straw from rapeseed (a crop widely grown in Northern Europe and Canada) contains more energy than the seed, yet because it is difficult to recover this energy  economically by present methods, it is wasted and the CO², usefully trapped in the straw, is released without benefit back to the atmosphere during natural decay.  All energy inputs including nitrogen fertiliser remain the same whether we use the straw or not, making the straw a free asset at harvest.  Using the straw doubles the energy balance to about 9:1 which is excellent.
 

Intact Harvesting

Agriculture and farming began in Middle-Eastern countries about 11,000 years ago. Since then, all over the world, intact harvesting has been used.  Until about 60 years ago, that is. 

Before then crops were harvested, dried and stored unseparated by binding, stooking and stacking.  The threshing was then done over the remainder of the year as grain and straw were needed.  Necessarily, the sheaf and sack had to be of a size a man could handle several times, and the whole process was very time-consuming.  Also a proportion of the crop was needed for the animal and human energy inputs.

 The invention and large-scale use of the combine harvester changed all that.  The different components of crops could then be separated during harvest.  Grain would be channelled into a holding tank or tractor trailer while the straw and chaff were dropped on to the ground.  

This and other inventions such as the pick-up baler, grain dryer and mechanical seed-drill, all running on cheap fossil fuel, increased manpower efficiency enormously and contributed greatly to parallel prosperity rises.  But this system is not as energy efficient as it could be.

Many farmers have both combine harvesters and balers and only use them for 200 to 300 hours per year.  Even more significantly the straw – the free asset mentioned earlier – is not used as an energy source.

 To rectify this, we could return to intact harvesting by using the high output big baler instead of the binder, glyphosate desiccation or swather instead of stooking, the telescopic handler instead of the pitchfork and the central threshing plant with integrated end-use facilities instead of the threshing drum.

 Existing tractor-drawn big-balers could be used, but to eliminate seed loss, a special harvester would be better.  The harvester would have a cutter/ pick-up header, a chopper to aid bale density and a normal big-baler mechanism.  Rotary brushes would strip the loose seed and grain from the outer layer of the bale from where it would fall onto a collecting floor and be elevated back to the intake elevator.  The processing plant would take the bales on a conveyor through a twine-remover to a rotor to break the bale down and direct the flow into a threshing mechanism.  The rapeseed would be crushed for biodiesel and the straw and cake burnt to produce electricity or better still, converted into cellulosic ethenol.  If the plant could be suitably sited, low grade waste heat could be used for district heating or glasshouse heating.  For wheat, it would be most economical if milling or grinding of the grain could be done on the same site.  If storing were needed and final moisture content was too high, some of the low grade heat could be used in a cascade dryer.  Again the wheat straw would be used for electricity generation or cellulosic ethenol.

Intact harvesting would reduce weed seed return and losses of crop seed normally associated with in-field threshing by combine harvesters.  It would also collect millings (weed seeds plus small light or broken grains) which studies in Canada has shown make a valuable animal feed. 

Local processing plants where the threshing would take place would have sufficient separation capacity to remove almost all the seed.  Working all year at 100 hours per week a threshing apparatus similar in size to that in a large combine could cope with around 20,000 hectares (50,000 acres) per year in high yielding areas and even more elsewhere.  This would also mean that farmers would only need to buy and use crop collecting machines rather than combine harvesters and balers.

There is already an electricity generating plant in Cambridgeshire, England that uses wheat straw harvested  conventionally.  It burns 200,00 tonnes of straw a year to generate 271.5 GWH of electricity per year, enough for 80,000 homes. However, recent advances in the production of cellulosic ethenol mean that rather than burn the straw for electricity, liquid road fuel can me made from the straw which will probably be needed more.  Electricity generation might be best left to the other renewables such as wind, water and tidal.

 The most efficient solution would be a bio-refinery dealing with the unthreshed (with the grain still attached to the stalk) crop, taking out the various products and leaving no waste.
 

In this way the amount of energy produced on every acre would almost double while at the same time the energy input required to harvest, dry and store the crop would be reduced.

Conventional Use of Corn Crop

Another example of our present wasteful use of solar energy captured by plants, is the use of corn (maize) to feed cattle for beef production.  Again the straw (stover) contains a similar amount of energy as that in the grain, but in the U.S. more than 90% of the stover is left in the fields.  Excessive surface stover makes the preparation of a seedbed for the next crop more difficult by no-till methods where the seed is sown directly into uncultivated land.  Consequently much of it is ploughed under using extra fuel and causing a speed up of the decay of soil organic matter and the release of CO².  Plowing also increases soil oxidation and the release of soil nitrogen to the atmosphere. 

Although it is of the utmost importance to protect soils from erosion, a small amount of crop residue on the surface together with roots and stubble, can be more effective at holding the soil together than the entire residue ploughed under.  

So after wasting half of the energy in the crop by plowing in the stover, we then feed the grain to cattle.  But because cattle are ruminants whose main role in food production is the utilisation of fibrous foods containing a large proportion of cellulose, the starch in the corn is largely wasted.  The cattle of course need energy for everyday activity and maintenance, so that the final amount of energy present in the beef compared with that in the original crop is extremely low.

Integrated Full Utilisation

 In our new age of efficient use of collected solar energy, we would deliver the entire crop to a unit where the starch in the grain would be used for ethenol.  The biproduct – distiller’s grains – which is protein, fat and some cellulose would be fed to the cattle.  Finally, the stover would be either burnt to provide the heat needed in the production of the grain ethenol, or used  to make cellulosic ethenol.

The cattle, which are kept in a feedlot close to the unit, produce beef or milk but also manure slurry.  This can be used in a biogas plant, preferably mixed with other waste products such as municipal food waste, catering waste and green city waste that would normally go to landfill sites.  The methane produced from these wastes by anaerobic digestion can power a gas engine to produce electricity, or can be used as the heat source in the ethenol plant. 
An integrated approach like this is so much more efficient.  One of the criticisms  levelled at present ethenol production is that because natural gas or coal is used for the process heat plus diesel and fertiliser inputs in the growing of the crop, the energy gain can in some cases be fairly low.
 

Ethenol from Wheat 
Production Plants Now being built in Europe using Natural Gas

In Europe, Canada and some other areas, facilities to produce ethenol from wheat and biodiesel from rapeseed are being built.  These are very large scale grain or seed-only facilities that will need a large catchment area with additional transport costs.  Smaller, integrated units using the straw  as well would be far more environmentally beneficial and cost effective.

Cellulosic Ethenol

Cellulosic ethenol is made from almost any organic material.  It has the potential to make a significant contribution towards supplying our energy requirements.  Many biotec companies are working hard to produce enzymes that are cheap enough to be used commercially, producing ethenol from cellulosic sources.

Genencor International, operating in the U.S. and the Netherlands; Novozymes Inc., of California; Iogen Corporation of Canada and companies in Germany and Britain are all claiming breakthroughs in cheaper enzymes.  Iogen, which is partly owned by Shell is planning commercial production from a plant in Canada which would use 500,000 tonnes of straw each year.
Hefty government funding to speed up the move from experimental work to really large-scale commercialisation would be justified, because this is probably the best way to turn sunshine into fuel without reducing food supplies.  The availability of crop residues, forest waste and crops such as miscanthus (elephant grass) grown on land not suitable for food crops is potentially enormous. 

According to Michael Want of the Argonne National Laboratory, cellulosic ethenol reduces GHG emissions to 80% below those of gasoline, compared to corn based ethenol reducing emissions by 20% to 30%.

Government-backed research on the very best way of utilizing the entire crop in a sustainable way is taking place, but not with the urgency that the situation demands.  This technology really does need to move to commercialisation at wartime speed.

On its website the U.S. Department of Energy gives details of a research and development project on the Integrated Corn-Based Bio-Refinery (ICBR) to demonstrate the practicality of producing alternative fuels and chemicals from renewable resources.  They explain that a key component of the project is the utilization of corn stover as feedstock.  Currently, the production of ethenol is based primarily on corn grain.  In order to expand ethenol production, lignocellulose materials such as corn stover will need to be utilised.  Because lignocelluloses are more difficult to hydrolyse than the starch in grain, part of the ICBR development will focus on the pretreatment of these materials.

To continue with a system that uses only part of the captured solar energy is surely using the mindset of the cheap fossil fuel era when the energy balance didn’t really matter.
In the case of rapeseed grown in Northern Europe, 1 hectare will yield about 13 tonnes of biodiesel equal to about 1,300 litres of diesel.  But if the 2 tonnes of cake residue and 7.2 tonnes/ ha of stem and pod were used for electricity, it would equate to 6 tonnes of coal per ha.  Polish and Danish findings put the gross energy consumption including fertiliser to grow and harvest 1 ha of winter rapeseed at under 21 GJ.  If just the oil is used, with about 45 GJ per hectare, the energy balance is only about 2 units of energy produced for each unit consumed.  If the oil, cake and straw are all used, with a total of 190 GJ/ hectare, this rises to an excellent 9 units of energy for every unit consumed.  As mentioned previously, as new technology becomes available cellulosic ethenol is probably a better use of the straw and cake than electricity.  The energy balance quoted would need to be reduced somewhat to take into account the transport and process energy needed but even mineral oil needs transporting and refining.

One of the reasons that ethenol production from sugarcane in Brazil is so successful is that the whole crop is utilized. The syrup is squeezed from the cane, then the residue, called bagasse is burned for process heat, giving an excellent energy balance.