Ever increasing global demand for energy, and its supply predominantly being fossil based, implies continued growth of emissions. Efficiency improvements and employment of nonfossil energy will definitely help mitigate the problem but it is generally recognized that ‘pure carbon offsets’ will have to play a major role if the problem has to be combated in a timely fashion. Discussion on pure offsets employing geological storage,(namely, Carbon Capture and Storage(CCS) is advancing rapidly. However major issues with this approach are its high cost and the long-term post operation liability.
The author has previously proposed an alternate approach of pure offset – the charcoal sequestration, which essentially employs conversion of dead plant material into inert solid carbon. Charcoal sequestration promises to be both less expensive and a better option as far as the operational and post-operation liability is concerned. One of the numerous advantages of the charcoal approach is its easier reversibility both in terms of liability and costs. Although implementation of this approach at a scale where it can make a significant impact on global CO2 concentration needs to be preceded by a substantial information dissemination and public preparedness, a practical way to introduce it is through using municipal solid waste (MSW) as the feed biomass for charcoal sequestration. This will not only allow time for public acceptance to evolve, and evaluation of potential associated risks, but already help mitigate the growing problem of space requirement for wastelandfills, waste transport costs, and emission of methane from the rotting municipal waste, associated with the continued urban sprawl.
This paper aside from describing the Carbon Sequestration from Waste (CSW) method, estimates the cost of carbon credit with this and other competing approaches such as the use of MSW for conversion to bio-alcohol, and for power generation. It highlights the difference between carbon credits associated with mobile energy needs (pure offsets) and stationary energy needs and makes a case for price duality of carbon credits. It also compares the global potential of CSW in combating GHG problem, making more than 2 wedges of Socolow with use of charcoal for soil enhancement and other purposes amounting to less than 0.04 such wedges. In this work the cost of carbon offset with CSW is estimated to be as low as C$2.6/tCO2e.
Excess CO2 emitted into the atmosphere on account of continued consumption of fossil fuels can be offset by capturing it at industrial sources and pumping it into deep geological formations1. The technology for CCS exists and is in use in the context of enhanced oil or gas recovery. Such CCS opportunities (coupled with another benefit e.g. EOR) represent the win-win application for this technology. There is no technical reason why it could not be extended to plain capture of CO2 from stack gases and its sequestration in deep saline aquifers. However, before humanity embarks on plain CCS on a massive scale for pure sequestration, we owe it to ourselves to consider pros and cons of this method versus other approaches and weigh all our options in a more systematic manner.
