**2.5. Algae**

The water impacts of algal propagation vary widely by technology and environmental conditions, with water use ranging from minimal up to 3,650 L L−1 of biodiesel or advanced biofuel produced [33]. Freshwater is needed to replace water losses from open ponds, even when halophilic organisms are used. While the volumes in photobioreactors are relatively small, cooling requirements, usually met by freshwater, are large. Water impacts of conversion technologies result from competition from often scarce freshwater supplies.

> time period might be several centuries or millenia, depending on climate and vegetation. Because of this long time factor, soils are considered to be non-renewable. They are heterogeneous and highly diverse components of ecosystems that form over long time periods under the influence of parent mineral material, climate, landscape position and biological activity. As the base of bioenergy production systems, soils constitute a major factor that interacts with water to determine the type and amount of plant biomass production (**Table 1**, [2]). They provide the physical anchor which tie plants to the earth, supply water and mineral nutrients for plant growth, decompose and recycle organic material and residues and mediate hydrological processes [39–41]. Bioenergy feedstock systems are part of agricultural and forest management systems that provide multiple ecosystem products and services [42]. These include plant biomass, water flow, water quality control, biodiversity, cultural heritage, and carbon storage. Soils are important factors in each of these services. Therefore, it is critical that in the process of managing soils for bioenergy production, soils must be managed to sustainably provide a wide range of ecosystem services important to human communities. Maintaining

**Black** = direct physical effect, **Green** = effect mediated through the crop specific attributes such as root or canopy structure, **Blue** = effect is both physical and plant -mediated

**Soil Texture Soil Organic** 

**Water Supply Availability S S S Soil Moisture S S W S Evaporative Losses M S W W** 

**Groundwater Recharge S S S**

**Table 1.** Interdependencies of water and soil resources (adapted from [2]).

Key: **S** = soil effect on water W = water effect on soil M = mutual effect

**Matter**

**Water Runoff M S S S W Precipitation Interception W** 

**Surface Water Turbidity S S S Eutrophication S S S**

**Mineral Nutrient Availability**

Impacts of Bio-Based Energy Generation Fuels on Water and Soil Resources

**Water Holding Capacity**

http://dx.doi.org/10.5772/intechopen.74343

**Erosion** 

119

The focus on renewable energy sources has raised concerns about environmental effects. In particular, the increase in the use of woody biomass, agricultural crops, agricultural residues and processing wastes residues as feedstocks for bioenergy production has intensified questions about potential impacts on water quality and soil sustainability. Intensification of

the quality of soils will ultimately ensure maintenance of water quality.

**4. Best management practices**

#### **2.6. Electrical generation impacts**

In general, water impacts of biomass powered electricity generation remain similar to fossil fuel pathways, with large water withdrawals but low consumptive use ranging from 0–1800 L MWh−1 [34]. Cooling water, which may contain some salts, is returned at higher temperature to the source stream or basin, with variable ecological impact. Water requirements for biofuel processing continue to improve. Use per tonne of feedstock has decreased dramatically for both corn and sugarcane ethanol. For instance, the consumptive water use of ethanol-sugar mills in Southeast Brazil has decreased from 15 m<sup>3</sup> Mg−1 of sugarcane bagasse prior to 2008 to <3 m<sup>3</sup> Mg−1 in 2008 [35]. However, in water stressed regions new or expanded facilities may still not be approved due to the associated water demand [35]. While, untreated effluent can create water quality problems, process water offers an opportunity to recover and recycle nutrients. Biofuel facilities with zero liquid discharge have been operating in the U.S. since 2006 and continue to expand worldwide. Technological improvements in water recovery and recycling have progressed to the point that some facilities are able to use municipal wastewater and some have achieved closed loop recycling of process water.
