Gasification Sees a New Dawn
If you search for gasification and terms like â€œwood stoveâ€ on video sharing sites these days you will see demonstrations of wood being burnt in little stoves which seem to something almost miraculous and quite different from our idea of wood as a fuel. These little boilers light rapidly, produce no detectable smoke after the initial lighting and firing, and burn very hot.
So what is the technique which is being used, and how might it help us all in weaning society off fossil fuels?
What you have seen is a method of gasification. It differs from combustion in that it uses just 20% to 30% of the air or oxygen necessary for complete fuel combustion. During gasification, the amount of air supplied to the gasifier is carefully controlled with the effect that only a small part of the fuel burns completely. Trials of this process have illustrated that up to 70% of the energy value of the fue used can be recovered as what is known as synthesis gas, or syngas. This producer gas can also be used for various applications similar to natural gas.
This is a part of the magic, and not one really shown in the YouTube type videos, but it makes this method even more useful. This is due to the fact that syngas can be put to useful work, in both drying the feed fuel prior to gasification and after collection and storage it can be used as a fossil fuel replacement, and renewable energy source. When a gasification plant also includes Combined Heat and Power (CHP) and/or electricity export from the site, the gains are even more impressive.
Gasification in addition promises to be the most efficient long-term solution for capturing carbon while utilizing these valuable feedstocks, and storing the CO2 for very long priods, to reduce or halt global warming.
Gasification of wood and wood-type residues and waste in fixed bed or fluidised bed gasifiers with subsequent burning of the gas for heat production is has become state of the art with designers of thes systems working hard to gain the absolute maximum efficiency out of these systems.
These wood gasifiers which are located primarily in the Scandinavian countries are used almost entirely for space heating heat generation. Gasification of biomass is the renewable fuel system preferred by many, and can be defined as the thermal conversion of solid biomass to gaseous fuel.
Gasification has been around for over a hundred years, but the benefits of biochar are only now being discovered. Furthermore, it is still a wide-open field.
Before electric lighting was available in cities there were street lamps fuelled by gasified coal. It is easy to forget that the process has been reliably used on a commercial scale worldwide for more than 50 years in the refining, fertilizer, and chemical industries, and for more than 35 years in the electric power industry. More than 75 companies involved in the development, licensing, and use of these technologies as well as engineering, construction, equipment manufacturing and production of synthesis gas by gasification from coal, petroleum coke, heavy oils and other hydrocarbons.
Gasification has been proven to be a viable technology for CO2 capture and reducing SOx, NOx, particulate matter, and mercury emissions from coal and petcoke-fired power plants, synthetic fuels production, and chemical facilities.
Plants in this category have been capturing carbon dioxide for several decades in chemical plants in China and the United States. It also has potential contributions to make to both transportation and electrical power energy markets. With ongoing concerns about the price and availability of oil, populous countries like the U.S. gasification has proven to be in high demand and quite successful. However, it can also be used in conjunction with gas engines and gas turbines to obtain a higher conversion efficiency than conventional fossil-fuel electric power generation. Gasification can help meet renewable energy targets, address concerns about global warming, and contribute to meeting global environmental targets.
Steve has built a great web site where there is a lot more information about gasification. This is a hot subject indeed for this technology which has become an essential read for all those in alternative energy and interested in taking action to reduce the impact of climate change.