“Regular” gasoline has a value of 85-92 g CO2 eq / MJ, while cellulosic ethanol, when derived from municipal solid waste, has a value of about 5 g CO2 eq / MJ. Ethanol from switchgrass will produce more CO2 eq / MJ. When coal is added the profile can be worse than regular gasoline.
Switchgrass (Panicum virgatum) is a summer perennial grass that is native to North america. It is known as the tall-grass of the prairie. This blog recently advocated for gasoline-powered automobile engines in the U.S. to run on an E10 blend. In the U.S., we use about 9.2 million barrels (219,000 gallons) of Finished Motor Gasoline a day. With the only difference, a barely discernible reduction in mileage, our gasoline could be blended with 10% ethanol to reduce carbon emissions.
The Biopact Team now informs* us that Austrians are driving on pure grass. Not on ethanol, but rather CNG (Compressed Natural Gas) obtained from fermenting smooth meadow-grass, which is known in the U.S. as Kentucky bluegrass.
(Poa pratensis is an important meadow species found extensively in Austria’s grasslands, where it is used by grazing livestock like cattle and sheep. The grass is grown and harvested in a sustainable manner. This feedstock was chosen because the species grows well with few inputs and it allows the landscape to be conserved. No new energy crops need to planted.
* Note: Biopact is pushing out the bio-gas tracts. This blog recently noted two other reports:
- Denmark is the European leader in developing biogas technologies when it comes to co-digestion of different biomass materials.
- In India, sugar producers are learning that distillery sludge, bagasse and spent wash make an excellent feedstock for anaerobic digestion.
Given that all the grass is converted into a useable fuel and organic fertilizer, one could consider biogas production a form of ‘cellulosic biofuel’: it doesn’t require easily fermentable sugars or starches – as do first generation liquid biofuels which rely on grains and oilseeds. As the Austrian project shows, a transport biofuel can be obtained from a cellulosic biomass feedstock like pure grass. Yield estimates for the biogas from grass are as follows: one hectare can yield between 2,900–5,400 cubic meters of pure methane per year, enough to fuel a passenger car for 40,000 to 60,000 kilometers (one acre of crops can power a car for 10,000 to 15,000 miles).
After the feedstock is harvested and anaerobically digested, raw biogas is obtained which consists of CH4, a large fraction of CO2 and trace gases. This crude green gas is then upgraded (CO2 removed) in a separate facility managed by Salzburg AG and purified to meet natural gas standards.
Beware the promise of CCS (Carbon Capture and Storage), it could be a false promise from those who would seem committed to business as usual above all else, to include survival of life as we know it on the planet.
A more environmentally friendly approach advocated by the IPCC is when the CO2 that is removed from the bio-gas, and also from the bio-methane, is used or stored rather than released into the atmosphere. Missing from the Biopact article is information about the grams of CO2 equivalent per kilometer traveled on bio-NG (the Salzburg AG name for a blend of 80% “natural gas” and 20% bio-methane) or if the amount of bio-methane in the blend is increased and the amount of natural gas decreased.
*Note: When comparing CO2 equivalents for various fuel choices, it is important to take into consideration not only emissions from operation, but also emissions from production, which for bioenergy would encompass cultivation and harvesting, and distribution.
Biopact informs that “carbon-negative bioenergy” can be obtained via a high-tech pathway. In its gaseous form CO2 is captured and sequestered “into geological sites such as depleted oil and gas fields, unminable coal seams or saline aquifers.” According to the Biopact team, such CCS (Carbon Capture and Storage) techniques currently are being developed by the coal industry. It also is a technology advocated by the petroleum industry. Both want credit for getting more fossil fuels to burning using such technology.
|Carbon dioxide, CO2||25-50|
|Hydrogen sulphide, H2S||0-3|
While it was noted that countries below the equator – most notably Argentina, Pakistan, and India – have converted public and private transport fleets to run on CNG (Compressed Natural Gas), until the recent biopact post, this blog was unaware that CNG was becoming so much more available in Europe.
According to Salzburg AG, natural gas is a very efficient and clean fuel, and for consumers there is a clear cost-advantage: with a typical mid-sized vehicle, filling up your tank with 10 euros worth of ‘bio-NG’ (80% natural gas and 20% biomethane) you can drive about 240 kilometers; for the same amount of money, diesel will bring you 155 kilometers and a tank of gasoline only 118 kilometers.
Compared to gasoline and diesel, both greenhouse gas emissions and air pollutants are reduced substantially. Natural gas alone cuts emissions by over 50% compared to diesel and 35% compared to gasoline. The higher the biogas fraction, the higher the CO2 reduction. When the biomethane share of the blend reaches 80%, the gas becomes entirely green and carbon neutral, because harvesting the grass from which it is made allows an increase in soil organic carbon, thus taking CO2 out of the atmosphere.
The combustion of natural gas and biogenic methane takes place in a quasi-total soot and particle-free way. Harmful exhaust gases – CO and NOx – are kept to a minimum.
“Mercedes-Benz launched its latest natural gas powered commercial vehicle, the Mercedes-Benz Econic NGT 1828 semitrailer tractor for urban and short-radius distribution, at the 2007 RAI International Commercial Vehicle Show in Amsterdam.” Mercedes-Benz also has shown a Natural Gas powered Sprinter at the UK Commercial Vehicle Show. According to Autoblog Green, “the company has also sold more than 1,500 Mercedes CNG buses and trucks.”
The Biopact team reports that in Eugendorf, Austria Salzburg AG has opened its first biomethane gas station for cars. The filling station offers a mixture of 80% natural gas and 20% biomethane at the same price as fossil natural gas.
“The gas station will initially have a capacity to service about 20 cars a day.” The company also is offering conversions of vehicles to natural gas. The cost of conversion is around 500 euros for private customers and 750 euros for commercial fleets. “With rising diesel and gas prices,” notes Biopact, “these costs are recuperated quickly.
Natural gas cars have the future: with low emissions and a high efficiency, natural gas powered vehicles are pollution free and economical. We have engaged ourselves for years in promoting pollution free transport and are proud to feed CO2-neutral biomethane into our natural gas net.- August Hirschbichler, executive committee, Salzburg AG
CNG conversion equipment must be certified for its performance, safety and quality. The conversion kit consists of a cylinder – to hold the CNG, and the necessary certified and tested pipes, fittings and pressure regulators to operate safely – which fits into the boot of any standard vehicle. Lixun is one of the largest manufacturers and exporters of conversion kit electric devices in China. In the European market, BRC Gas equipment and Lovato are major suppliers.
With concerns that global production of natural gas is peaking, efforts are underway to convert biomass to a suitable CNG alternative. Bio-gas is a mixture of methane and other gases and water vapor. When bio-gas is “cleaned up” to the quality of natural gas in pipelines, it is called renewable natural gas or bio-methane.
Salzburg AG built the first part of a new dedicated gas infrastructure – a 2 kilometer pipeline – which feeds the upgraded biogas into its existing local natural gas grid. In 2008, the company will supply this ‘Bioerdgas’ to 14 similar stations that currently offer natural gas in the city and federal state of Salzburg . The regional energy administration is the station’s first customer and will run its fleet on the clean gas.
Regional energy administrator Sepp Eisl, who is also a national energy advisor, says…
In the future, we will pursue the goal of ensuring that 80% of all driven kilometers are based on biogas. This fuel production pathway is absolutely innovative and pollution free, for several reasons: the biogas is produced without any inputs of synthetic fertilizers or pesticides. Its is locally produced and does not require any transportation. Local jobs are created and secured, and regional value is created because the project contributes to landscape conservation.