Sequestering Carbon Dioxide by the Use of the Energy Crop Miscanthus: Quantifying the Energy Production and Sequestration Potential of Europe
Authors: Hastings Astley F. , Clifton-Brown John , Wattenbach Martin , Mitchell Paul , Smith Pete 
Published: December 2007

Global warming caused by anthropological emissions of greenhouse gas (GHG) is now an inconvenient reality. CO2, the largest contributor, was emitted at the rate of 6 Gt C y-1 by burning fossil fuels in 1990, which are projected to rise to around 10 Gt C y-1 by 2020. Using bio-fuels, such as bio-ethanol or bio-diesel in transportation, or biomass in power generation reduces CO2 emissions as the carbon is fixed by the plants from the atmosphere and saves the equivalent fossil fuel.

The biospheric flux of carbon from the soil and terrestrial biota to the atmosphere is about 120 Gt C y-1 and is roughly balanced by the fixation of carbon by photosynthesis. However, anthropological land use change, through increased agriculture and forestry, resulted in atmospheric emissions of 1.1 Gt C in 1990, projected to rise to 1.5 Gt C in 2020, so the production of biofuels is not GHG emission free if land use change is involved.

This paper explores the GHG emission cost of the production of bio-fuels derived from energy crops and compares them to fossil fuels used in transport and electricity generation. The bio-fuels emission cost are presented for several land use scenarios showing that highest sequestration can be achieved by using existing arable land for bio-fuel production and not land with a currently undisturbed ecosystem.

Considering these drivers and the GHG emissions, we model the future potential of Europe to produce bio-fuels with four different future land use and climate change scenarios and conclude that up to 20% of Europe's current primary energy consumption could be provided by bio-fuels by the year 2080 with a corresponding reduction in carbon emissions, taking into account the GHG cost of production.

Introduction

The global pattern of energy use is changing with the successive industrialization of the economies of South East Asia and Brazil, and more recently with the increasing pace of the industrialization of China and India. This has driven an increase in the demand for energy, and hence for fossil fuel, at the rate of 2–3% per year 1. The rate at which conventional oil production can be increased has been reduced by the lack of refining capacity, and the fact that nearly 50% of the world's proven and probable conventional light crude oil reserves have already been consumed 2. This flat-topping in the availability of oil has been compensated for by the increased availability of natural gas and new reserves of cheap coal. Natural gas has been increasing its share of the energy supply mix as the infrastructure and technology of its transportation is put into place both by pipelines, liquefaction and conversion to methanol. In developed economies, gas has displaced both oil and coal, whilst coal use has increased in developing economies, particularly in China. At the same time the use of nuclear energy has stagnated due to public concerns about waste storage and disposal.

Globally, biomass currently provides around 46 EJ of bio-energy in the form of combustible biomass and wastes, liquid bio-fuels, renewable municipal solid waste, solid biomass/charcoal, and gaseous fuels. This share is estimated to be 13.4% of global primary energy supply 3 but this is mainly from "traditional biomass" estimated to provide 32EJ in 2002 of non-commercial firewood, charcoal and dung used for cooking and heating in developing countries 4. Such low-grade biomass provides around 35% of primary energy in many developing countries, but more than 70% in Africa 5.