1. Bio-Mass Technology
Energy generation from biomass is considered a renewable energy generation technology. In the diagram below there is a clear classification of all energy technologies that are in commercial use at this time in the evolution of mankind on earth.
Biomass Energy originates from ethanol (derived from sugar-cane), wood or wood derived Biomass ( pellets) and municipal bio-waste.
Most biomass refers to plants or plant-derived materials.As an energy source, biomass can either be used directly via combustion to produce heat, or indirectly after converting it to various forms of biofuel. The conversion of biomass to biofuel can be achieved by different methods which are classified into: thermal, chemical, and biochemical methods.
Wood remains the largest biomass energy source today. Examples include forest residues, yard clippings, wood chips and municipal waste. Biomass also includes plant or animal matter that can be converted into fibers or other industrial chemicals or biofuels. Industrial biomass can be grown from numerous types of plants such as miscanthus, hemp, corn, sugarcane, bamboo, willow , poplar, eucaliptus and palmoil.
Plant energy is produced by crops specifically grown for use as fuel that offer high biomass output per hectare. Some examples of these plants are wheat, which typically yields 7.5-8 tonnes of grain per hectare, and straw, which typically yields 3.5-5 tonnes per hectare.
The grain can be used for liquid transportation fuels while the straw can be burned to produce heat or electricity. Plant biomass can also be degraded from cellulose to glucose through a series of chemical treatments. The resulting sugar can then be used as a first generation biofuel.
Biomass can be converted to other usable forms of energy like methane gas or transportation fuels like ethanol and biofuels. Rotting garbage, and agricultural and human waste, all release methane gas, called biogas.
Crops, such as corn and sugar cane, can be fermented to produce the transportation fuel, ethanol. Biodiesel, another transportation fuel, can be produced from left-over food products like vegetable oils and animal fats.
There is a great deal of research involving algal, or algae-derived, biomass due to the fact that it’s a non-food resource and can be produced at rates 5 to 10 times faster than other types of land- based agriculture, such as corn and soy. Once harvested, it can be fermented to produce biofuels such as ethanol, butanol, methane, hydrogen and biodiesel.
The biomass used for electricity generation varies by region. Forest by-products, such as wood residues, are common in the USA. Also agricultural waste is commonly used such as sugar cane residue an rice husks.
2. Biomass Share of Energy Market
The diagram below indicates that Biomass accounts for about 16% of the global market of renewable energy.
As can be seen from the diagram below renewable energy accounts for about 16% of the global energy consumption. Fossil Fuels are the predominant raw materials for energy production. Nuclear fuels account for 2.8% and total biomass for 2.5% of the global energy market.
3. Biomass Environmental Impact
Using biomass as a fuel produces air pollution in the form of CO, CO2, NOX and PM pollution, in some cases at levels above those from traditional fuel sources such as coal, liquid fossil fuels or natural gas.
Biomass is sometimes considered a carbon neutral source of energy because the carbon dioxide released into atmosphere by using biomass is recovered again by growth of new biomass. In contrast, use of fossil fuels, releases “new carbon” which has been locked away in the form of hydrocarbon fuels in the earths crust since millions of years. When the biomass is from forests, the time to recapture the carbon stored is generally longer, and the carbon storage capacity of the forest may be reduced overall if destructive forestry techniques are employed.
The diagram below indicates that biomass has a relatively low GHG emission, compared with solar energy and hydro-electric derived energy. However there is much discussion about the integral environmental effects of the application of biomass for energy production.
The proposal that biomass is carbon-neutral put forward in the early 1990’s has been superseded by more recent science that recognizes that mature, intact forests sequester carbon more effectively than cut-over areas.
When a tree’s carbon is released into the atmosphere in a single pulse, it contributes to climate change much more than woodland timber rotting slowly over decades. Current studies indicate that even after 50 years the forest has not recovered to its initial carbon storage and the optimal strategy is likely to be protection of the standing forest.
Forest-based biomass has recently come under fire from a number of environmental organizations, including Greenpeace and the Natural Resources Council for the harmful impacts it can have on forests and the climate. In this context Greenpeace recently released a report entitled “Fuelling a BioMess”, which outlines their concerns around forest-based biomass.
Because any part of the tree can be burned, the harvesting of trees for energy production encourages whole-tree-harvesting, which removes more nutrients and soil cover than regular harvesting, and can be harmful to the long-term health of the forest.
In light of the pressing need to reduce greenhouse gas emissions in the short term in order to mitigate the effects of climate change, a number of environmental groups are opposing the large- scale use of forest biomass in energy production.
Growing Biomass requires land, the use agrochemicals and extracts valuable nutrients from the land. It is more efficient to use the biomass as a feedstock for the production of compost. Composting keeps the carbon in available to the soil, reduces the need for agrochemicals, eliminates GHG emissions and recycles the valuable nutrients into the soil. Valuable nutrients should not be used as a fuel and should be avoided whenever it can.
For this reason the use of biofuels will meet with increasing public social protest in the future.
4. Biomass Energy Production Economics
The EIA projects that by 2017, biomass is expected to be about twice as expensive as natural gas, slightly more expensive than nuclear power, and much less expensive than solar panels.
The International Renewable Energy Agency (IRENA) points out that recent years have seen dramatic cost reductions as a result of research and development and accelerated deployment.
IRENA estimates that the total installed costs of stoker boilers ranged between $1,880 and $4,260 per kilowatt (kW) in 2010, while those of circulating fluidized bed boilers were between $2,170 and $4,500 per kW. Anaerobic digester power systems had a significantly wide range of capital costs from $2,570 up to $6,100 per kW, and gasification technologies had total installed capital costs of between $2,140 and $5,700 per kW.
The capacity factors of Biomass facilities varies a great deal depending on the kind of feedstock, location and size. IRENA reports that capacity factors can vary between 30% and 80%.
If we assume an average capacity factor of 55% then we can deduce that the average effective cost of biomass installations is in the range: 4000-10.000 US$/KW installed capacity.