Due to the rising demands of fuels combined with efforts in reducing greenhouse gas emission, countries all over the world are looking for alternative clean energy sources such as biofuel. Ethiopia imports a huge amount of fuel each year and to supplement its energy needs efforts are underway for biofuel development. Despite this, comprehensive assessments of the suitable sites for biofuel feedstocks are lacking. This study is designed to map suitable sites for selected biodiesel feedstocks (Jatropha, Castor, Croton, and Cottonseed) and bioethanols (Cassava and Sweet Sorghum) and estimating the potential productions in Ethiopia. The spatial representations of the requirements (Soil, Elevation, Rainfall, and Temperature) of the feedstocks were created and processed to eventually map the suitable sites. About 16, 30, 28, 34%, 6, 83% of the country is highly suitable (HS) for Jatropha, Castor, Croton, Cassava, Cottonseed and Sweet Sorghum, respectively. The suitability assessments were also made by excluding environmentally sensitive lands (e.g marshy areas, parks, wildlife sanctuaries and forests) and areas that can compromise crop production (e,g, cultivated lands). Accordingly, 6, 9, 7, 10, 2 and 36% of the country remains HS, thus large scale biofuel production can be conducted without affecting food security and the environment in these areas. Hence, the country can produce up to 355.44 and 225.09 billion liters of biodiesel and bioethanol, respectively, returning up to 53 billions USD overall revenue.

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Global environmental changes have implications for the terrestrial ecosystem functioning, but disentangling individual effects remains elusive. The impact of vegetation responses to increasing atmospheric CO2 concentrations is particularly poorly understood. As the atmospheric CO2 concentration increases, the CO2 acts as a fertilizer for plant growth. An increase in atmospheric CO2 reduces the amount of water needed to produce an equivalent amount of biomass due to closing or a narrowing of the stomata that reduces the amount of water that is transpired by plants. To study the impacts of climate change and CO2 fertilization on plant growth, we analyzed the growing season sensitivity of plant growth to climatic forcing from alpine to semi-desert eco-climatic zones of Ethiopia for various plant functional types over the period of 1982–2011. Growing season 3rd generation Normalized Difference Vegetation Index of Global Inventory Modeling and Mapping Studies (NDVI) was used as a proxy of plant growth, while mean growing season precipitation (prec), temperature (temp), and solar radiation (sr) as the climate forcing. The sensitivities of plant growth are calculated as a partial correlation, and a derivative of NDVI with respect to prec, temp and sr for earliest and recent 15-year periods of the satellite records, and using a moving window of 15-year. Our results show increasing trends of plant growth that are not explained by any climate variables. We also find that an equivalent increase in prec leads to a larger increase in NDVI since the 1980s. This result implies a given amount of prec has sustained greater amounts of plant foliage materials over time due to decreasing transpiration with increasing CO2 concentration as expected from the CO2 fertilization effect on water use efficiency and plant growth. Increasing trends of growth in shallow-rooted vegetation tend to be associated with woody vegetation encroachment.

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