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    Mongabay, a leading resource for news and perspectives on environmental and conservation issues related to the tropics, has launched Tropical Conservation Science - a new, open access academic e-journal. It will cover a wide variety of scientific and social studies on tropical ecosystems, their biodiversity and the threats posed to them. Tropical Conservation Science - March 8, 2008.

    At the 148th Meeting of the OPEC Conference, the oil exporting cartel decided to leave its production level unchanged, sending crude prices spiralling to new records (above $104). OPEC "observed that the market is well-supplied, with current commercial oil stocks standing above their five-year average. The Conference further noted, with concern, that the current price environment does not reflect market fundamentals, as crude oil prices are being strongly influenced by the weakness in the US dollar, rising inflation and significant flow of funds into the commodities market." OPEC - March 5, 2008.

    Kyushu University (Japan) is establishing what it says will be the world’s first graduate program in hydrogen energy technologies. The new master’s program for hydrogen engineering is to be offered at the university’s new Ito campus in Fukuoka Prefecture. Lectures will cover such topics as hydrogen energy and developing the fuel cells needed to convert hydrogen into heat or electricity. Of all the renewable pathways to produce hydrogen, bio-hydrogen based on the gasification of biomass is by far both the most efficient, cost-effective and cleanest. Fuel Cell Works - March 3, 2008.

    An entrepreneur in Ivory Coast has developed a project to establish a network of Miscanthus giganteus farms aimed at producing biomass for use in power generation. In a first phase, the goal is to grow the crop on 200 hectares, after which expansion will start. The project is in an advanced stage, but the entrepreneur still seeks partners and investors. The plantation is to be located in an agro-ecological zone qualified as highly suitable for the grass species. Contact us - March 3, 2008.

    A 7.1MW biomass power plant to be built on the Haiwaiian island of Kaua‘i has received approval from the local Planning Commission. The plant, owned and operated by Green Energy Hawaii, will use albizia trees, a hardy species that grows in poor soil on rainfall alone. The renewable power plant will meet 10 percent of the island's energy needs. Kauai World - February 27, 2008.

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Friday, June 20, 2008

Carbon-negative cars could mitigate 646% of global transportation CO2 emissions

The all-electric Tesla Roadster. Will this car become a machine that helps remove CO2 from the atmosphere, instead of being merely a 'zero emissions' vehicle?
Imagine driving your car and, while doing so, taking carbon dioxide out of the atmosphere. Forget 'zero emissions' vehicles. Think 'negative emissions' cars instead. This bizarre idea can become reality when the car in question is powered by carbon-negative bioenergy. Electric and fuel cell cars powered by negative emissions electricity or hydrogen made from biomass the carbon of which has been captured and stored, can help save the climate by cleaning up our emissions from the past.

Scientists (like NASA's Dr James Hansen) are increasingly taking the exotic concept of negative emissions energy (also known as bioenergy with carbon storage) serious, and have begun to explore its potential. A series of articles in the April issue of the leading journal Climatic Change is entirely devoted to it.

In the editorial essay, Dr Peter Read (Centre for Energy Research, Institute for Technology and Engineering, Massey University) outlines ways to manage global carbon fluxes by relying on biomass systems capable of capturing carbon dioxide from the atmosphere while generating energy in the process. Nuclear power and renewables like solar, wind or hydropower are often seen as green energy technologies, but in truth they are condemned to remaining 'carbon-neutral' at best; that is, they yield low emissions energy, but can never actively remove CO2 from the atmosphere, which is something we might want to begin doing. Carbon-negative bioenergy systems on the contrary are far more radically green, because capable of providing energy while sequestering atmospheric CO2.

If implemented on a large scale, such negative emissions energy systems can at the same time power our societies and take us back to pre-industrial CO2 levels, writes Read. In the event of 'abrupt climate change', these biobased 'geo-engineering' options are the only safe way to prevent catastrophy. (Note, in his seminal paper on the carbon-reduction aim humanity should set itself, James Hansen sees carbon-negative bioenergy systems as key to achieving his 350ppm target - previous post).

In a comment to Read, James S. Rhodes (Dept. of Engineering, Carnegie Mellon University) and David Keith (ISEEE Energy and Environmental Systems Group, University of Calgary) analyse [*.pdf] both the constraints to and the most efficient use of negative emissions energy systems.

According to them, the largest potential for carbon-negative bioenergy, as far as its carbon mitigation capacity is concerned, can be found in coupling it to the transport sector, because this is the sector in which reducing emissions is most difficult. Liquid biofuels used in internal combustion engines are not a smart way to use biomass, because these fuels are 'carbon neutral' at best. Instead, using the biomass to produce negative emissions electricity or biohdyrogen for use in EVs and fuel cell vehicles can take us much further.

So how much CO2 can be mitigated in the transport sector? If an optimistic scenario about future biomass supplies is taken (a supply worth 1130 Exajoules by 2050), Rhodes and Keith obtain the following numbers:
  • The percentage that can be mitigated with substitution by (carbon-neutral) liquid biofuels only is 134% maximum
  • The percentage mitigated with substitution and offsets via CCS is 565% (calculated by multiplying the potential biomass supply (Mt year−1 ) by an assumed mass fraction carbon in biomass of 50%, multiplying by an assumed carbon capture rate in production of 50 to 60%, converting to Mt CO2, dividing by the fossil CO2 emissions (Mt CO2 year−1 ) and adding the percent mitigated with substitution only)
  • The percentage mitigated by using decarbonised fuel (hydrogen) from biomass with CO2 capture is 646% (calculated by multiplying the potential biomass supply (Mt year−1 ) by an assumed mass fraction carbon in biomass of 50%, multiplying by an assumed carbon capture rate in production of 90%, converting to Mt CO2, and dividing by the fossil CO2 emissions (Mt CO2 year−1 )
So what does this mean? It means that vehicles using carbon-negative bioenergy could potentially reduce emissions not only to zero, but go beyond this and capture up to 6 times as much CO2 from the atmosphere than is put into the atmosphere if all cars were fossil fuel powered vehicles. In other words: the more we were to drive such carbon-negative cars, the more actively we would be mitigating climate change... Cars would become carbon-mitigating machines.

For readers new to this counter-intuitive concept we will quickly summarize the different ways to produce negative emissions energy. They all rely on a supply of renewable biomass. Once we have access to such a supply, the following options emerge:
:: :: :: :: :: :: :: :: :: :: ::
1. use the biomass to produce electrictity in integrated gasification combined cycle (IGCC) or oxyfuel combustion power plants, which allow for the easy capture of the carbon. After the carbon has been captured in the form of CO2 gas, it can be safely sequestered in geological formations like saline aquifers or depleted oil and gas fields (mind you, the gas is biogenic in origin, so any CO2 leakage would not constitute a problem; this in contrast with CO2 of fossil origin). After you have used the energy and applied carbon capture and storage (CCS) to it, regrow the biomass. As they grow, the crops will again take CO2 out of the atmosphere. Then repeat the process: extract the energy from the crops to power cars (or whatever needs to be powered), and sequester the CO2 once more.

2. the biomass can also be used to make biohydrogen directly. During the production phase (biological or thermochemical pathways), CO2 is released and can again be captured before it enters the atmosphere. It is then geosequestered via CCS, as in the first option.

3. a third technique to make negative emissions energy consists of using the biomass in slow pyrolysis plants that simulatenously yield syngas and biochar. The biochar is stable black carbon that can be sequestered in a solid form in soils for millennia. When biochar is stored in nutrient-poor soils (like the soils in the tropics), it can make agricultural land more fertile (allowing for even faster and better growth of the biomass). The syngas from the slow pyrolysis operation can then be used to generate electricity.
Any of these types of negative emissions energy can then be used in an electric vehicle or in a hydrogen fuel cell car.

Carbon-negative bioenergy does not present any of the troubles typical of classic 'geoengineering' concepts which are aimed at halting abrupt climate change. The effects of such geoengineering ideas, like blowing large amounts of sulphur into the atmosphere, feeding iron to oceans to induce algae blooms, or launching mirrors into space, are far more uncertain. These techniques are also much more costly than negative emissions energy.

Rhodes and Keith conclude that despite social, economic and environmental constraints:
Biomass-CCS and its unique attributes should be more deeply integrated in climate policy making. The implications of biomass-CCS are potentially large and are inadequately reflected in current climate policy debates.
It will take a while before mainstream climate policy makers, environmental organisations and media outlets catch up with the radically green potential of carbon-negative bioenergy systems. But eventually they will. One of them, Norway's Bellona Foundation, has already done so. In its most recent report on options to mitigate climate change, it referred to negative emissions energy for the first time ("you can watch TV and by doing so take CO2 out of the atmosphere"). Others are being introduced to the concept because of Hansen's crucial paper. And of course, still others are learning about it by reading Biopact - the only organisation that has been actively reporting on this issue.

Because the use of carbon-negative bioenergy in the transportation sector implies the use of electric vehicles and/or fuel cell cars, Biopact will be tracking news about the development of such vehicles more in-depth. If we want to use biomass and the land needed to grow it in the most radical way to solve the climate problem, we might want to abandon liquid biofuels and the internal combustion engine altogether. What is more, the concept of carbon-negative energy as the basis for transport is interesting for the developing world. Instead of investing in liquid biofuels, poor countries could 'leapfrog' beyond the internal combustion engine, and choose for electric transportation infrastructures. Such infrastructures could at once tap into other renewables, like solar or wind, even though these energy sources remain carbon neutral at best.

Over the coming months, we will explore what carbon-negative bioenergy in the transport sector might mean for developing countries. We will especially focus on the biochar route, because this pathway seems to be the most feasible and least costly of the negative emissions energy production options.

Image: Tesla Roadster. Credit: Tesla Motors.

Peter Read. "Biosphere carbon stock management: addressing the threat of abrupt climate change in the next few decades: an editorial essay", Climatic Change, Volume 87, Numbers 3-4 / April, 2008, page 305-320, doi: 10.1007/s10584-007-9356-y.

James S. Rhodes and David W. Keith, "Biomass with capture: negative emissions within social and environmental constraints: an editorial comment" [open access], Climatic Change, Volume 87, Numbers 3-4 / April, 2008, page 321-328, doi: 10.1007/s10584-007-9387-4.

Biopact: Carbon-negative bioenergy making headway, at last - June 06, 2008.


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