Total energy used in USA=96 quadrillion Btus (Quads)/yr. USA area =2.37 billion acres. Assuming 1 billion acres useable, producing 4000lbs/acre/yr at 6000 btus/lb, per acre energy production/yr would be 24 million btus. Total energy produceable/yr from biomass would be 24 quads. These numbers can be massaged up or down. However, biomass growth is limited by fertilizer, water, soil quality, labor, and governmental wisdom. We need a mass tree planting program right now. It seems unlikely that we could produce more than 20 quads of biomass per year. However biomass is the most useful alternate energy because it is useful in the winter, at night, when the wind is not blowing, and the sun is not shining. The ashes may be crucial for fertilizer, and legumes in bio digesters may be able to produce food, energy, and nitrogen fertilizer.
For trees planted on a 10 feet grid, 400 trees could be planted on 1 acre, so 400 billion trees could be planted on 1 billion acres. Assume 100 billion trees in US at 1000 lbs/tree, 6000 btus/lb. Assume that it takes 50 years say the tree reaches 1000 lbs. The accumulated energy storage would be 2.4 billion btus/acre. The total US energy storage of wood, would be 2400 quads. At $1 per tree the cost of planting would be 100 billion dollars. This calculation shows double the yearly energy production the previous one did. However these numbers are accurate enough to show how valuable a mass tree planting program would be to our grandchildren. Also Global Warming would be reduced by the storage of carbon.
Since there will not be enough Biomass it should be used primarily in winter for cogeneration and co-manufacturing. By doing this any waste heat can be used to heat buildings and much energy is saved.
Wood should not be burned in fireplaces or wood stoves to heat houses because that is too inefficient. Instead wood energy must be converted to both energy and heat. The traditional way of doing this is by boiler and steam engine. This system will undoubtedly be used. However another way is to gasify the wood by burning it with insufficient oxygen. This produces a poisonous burnable gas which can be used in internal combustion engines, thus eliminating the boiler and condenser. From this gas it is also possible to make methanol which is a possibility for tractor fuel. It is also possible to power tractors and other vehicles from wood by mounting the wood gas generator directly on the vehicle. My belief is that making methanol in winter as a co-manufacturing process would be the best way to provide fuel for agriculture which does not depend on oil. Charcoal is a better fuel than wood and is easier to adapt to vehicular operation. However there is much heat and gaseous energy lost in making it. Therefore charcoal could also possibly be manufactured in winter as a co-manufacturing process.
Bio-methane can also be made in a large vessel using soft biomass such as sewage, leaves, grasses, paper, saw dust, and stalks using an anaerobic bacterial digestion process. From this gas it is also possible to make methanol. Again a co-manufacturing process is best. The biggest advantage of this biodigestion is that nitrogen is retained in the effluent from the process. This means that it is possible to manufacture both energy and fertilizer from leguminous plants and sewage.
Using fermented grain to make ethanol has been characterized as a break- even energy process not worth doing. However if the fermentation and distillation processes were done in winter as co-manufacturing processes then the energy balance would be much more favorable. It also might be possible to grow wood and fruit by mass planting apple trees. Any surplus of apples could also be used to make ethanol with no plowing costs. Potatoes might be a more energy effective ethanol crop than grain.
Since fertilizer will also be scarce all sewage, manure, ashes, and residues from biomass processing must be carefully saved and used as fertilizer.
In my opinion, a mass planting of fruit and nut trees might save millions of lives in 2050. The question is whether the people care enough about the little children to plant them.
Kermit Schlansker PE