Every fact about the Sun is hard for most of us to take in. The numbers are so huge it makes us and our Earth seem very small and insignificant. When we feel the heat of the Sun on our face, it is hard to believe that it has come from 150 million km away. Just a tiny fraction of the Sun’s energy hits the Earth, yet every minute enough energy arrives to meet our demands for a whole year if only we could harness it properly.
For many people, their opinion on climate change is more a religious type of faith rather than one based on science. It’s understandable because most of us are not experts and must rely on the work of those who are.
The farmer’s job is to manage the original solar energy collector-the plant leaf. We use the sun’s energy collected by plants to take the carbon from carbon dioxide and the hydrogen from water to synthesise carbohydrates and give off oxygen. When the carbohydrate is eaten, burned or it just decays, the opposite happens- oxygen is required, carbon dioxide and water are given up and energy is released.
Of course, this is nothing new. This cycle was working perfectly well long before farmers came on the scene. We merely try to improve on nature by fighting pests and disease, by providing optimum nutrition and by trying to eliminate plants from our fields other than those that we wish to harvest.
Green plants are the only primary producers of foodstuffs and humans are dependent on plants for all of their food, either directly or indirectly. All of our human energy comes from the sun and the feeding of the world depends on our ability to collect enough solar energy and convert it to food energy through farming plants .It used to be so simple. Around 30% of crops were used to fuel the horses, oxen and humans to provide the muscle for field and transport work. Soil fertility was maintained by recycling nutrients, crop rotation including nitrogen fixing legumes and fallows. Yields were low but so was the world population.
But in the past 70 years or so there has been a dramatic development that has enabled the world population to triple. WE have found a way to cheat!
Instead of just converting current sunshine in to food energy we have found how to convert ancient sunshine collected by pre-historic plants and marine organisms in to food energy.
We now convert hydrocarbons in to carbohydrates.
The present population of nearly7 billion people is being supported not just on current sunshine but on sunshine that reached this earth millions of years ago.
The land previously used to feed work animals can now be used to provide human food as diesel engines provide the muscle. Fossil fuel sourced pesticides and nitrogen fertiliser have dramatically increased yields and enabled the green revolution in India and elsewhere.
Amazingly, if transport and processing is included, we now use about 10 calories of fossil energy to produce each calorie of food energy in an average meat based diet.
Converting fossil energy in to a smaller amount of more expensive food energy worked well when fossil energy was cheap and plentiful but will fail when it is scarce and expensive.
We have said many times that when finite oil supplies become scarce we will reach a situation of Peak Food because our farming system is now totally dependent on these fossil reserves.
So it’s good to see that at least one major tractor maker is looking to make a tractor that does not run on oil based fuel.
The NH2 tractor is a working prototype with fuel cells that generate 106 horse power. Hydrogen, stored at 350bar in a tank under the bonnet, is passed over one electrode, while oxygen (from an air pump) is passed over the other. The electricity produced by the process then passes to a pair of electric motors, one supplying drive and the other providing power for pto and auxiliary services. Because it runs on hydrogen and oxygen, the tractor’s only by-product is water.
There are at least two problems:
- Fuel cells are prohibitively expensive, though New Holland hope that commercially viable cells could come on line as soon as 2018!
- Hydrogen is really an energy storage means and needs an energy source. The conversion of energy into hydrogen, the transportation and storage of the hydrogen and its conversion back into electricity by fuel cells is very inefficient but New Holland has a vision of an energy independent farm that generates electricity on the farm using wind, solar or biogas, and then using an electrolyser to produce hydrogen which is stored in a high pressure tank.
Plainly, developing the tractor and setting up the infrastructure is not going to be a quick solution and may never be viable. However, we must give New Holland full marks for recognising that fossil powered farming can only be temporary and attempting to come up with an alternative.
In the past, ancient solar energy stored as fossil fuel has been so cheap that there has been little incentive to find ways to waste less. Similarly, with current solar energy collected by plants, not only do we waste the energy in millions of tonnes of waste food that goes in to landfill, but the methane gas given off – unless collected – is a very powerful greenhouse gas.
There are now encouraging signs that this is starting to change. A fantastic example is the potato packing and processing plant belonging to Fenmark in Cambridgeshire. Their new anaerobic digestion unit will divert thirty thousand tonnes of food waste each year from landfill to generate electricity and provide heat for water and space heating with the by-product sold as a soil conditioner.
One small step towards food security.