The scalability and costs associated with producing bioenergy at larger commercial scales is dependent on a variety of factors related to the specific biomass feedstock, conversion technology, location, and intended energy products. In general though, as the scale of bioenergy production increases there are opportunities to lower the costs per unit of energy output through economies of scale.
Larger facilities are able to amortize capital equipment and infrastructure costs over higher volumes of biomass throughput. This reduces the capital expense per ton of biomass or gallon/MMBtu of biofuel/biopower. Bigger also usually means more automated, which lowers operating labor costs. Purchasing feedstocks and other inputs in larger bulk quantities can yield price discounts as well. Transportation logistics become more efficient with bigger volumes moved per load.
Scaling up also faces challenges that impact costs. Larger facilities require bigger land areas to produce sufficient feedstock supply. This often means infrastructure like roads must be developed for transporting feedstocks over longer distances, raising costs. Finding very large contiguous tracts of land suited for energy crops or residue harvest can also drive up feedstock supply system costs. Permits and regulations may be more complex for bigger facilities.
The types of feedstocks used also influence scalability and costs. Dedicated energy crops like switchgrass are considered very scalable since advanced harvesting equipment can efficiently handle high volumes on large land areas. Establishing new perennial crops requires significant upfront investment. Agricultural residues have lower risk/cost but variable/seasonal supply. Waste biomass streams like forest residues or municipal solid waste provide low risk feedstock, but volumes can fluctuate or transport may be over longer distances.
Conversion technologies also impact costs at larger scales differently. Thermochemical routes like gasification or pyrolysis can more easily scale to very large volumes compared to biochemical processes which may have technological bottlenecks at higher throughputs. But biochemical platforms can valorize a wider array of lignocellulosic feedstocks more consistently. Both technologies continue to realize cost reductions as scales increase and learning improves designs.
Location is another factor – facilities sited close to plentiful, low-cost feedstock supplies and energy/product markets will have inherent scalability and cost advantages over more remote locations. Proximity to infrastructure like rail, barge, ports is also important to reduce transport costs. Favorable policy support mechanisms and market incentives like a carbon price can also influence the economics of scaling up.
Early commercial-scale facilities from 25-100 dry tons/day for biochemical refineries up to 300,000-500,000 tons/year for biomass power have demonstrated capital costs ranging from $25-50 million up to $500 million depending on scale and technology. At very large scales of 1-5 million dry tons/year, facilities could reach over $1 billion in capital costs.
Studies have shown that even at large scales, advanced biomass conversion technologies could achieve production costs competitive with fossil alternatives under the right conditions. For example, cellulosic ethanol plants processing over 1000 dry tons/day using technologies projected for 2025 could achieve ethanol production costs below $2/gallon. And giant co-fired biomass power facilities exceeding 500,000 tons/year may reach generation costs below 5 cents/kWh.
The scalability of bioenergy production is proven, with larger scales generally enabling lower costs per unit of energy output. Further technology improvements, supply chain development, supportive policies, and market demand can help realize the full potential of cost-competitive, sustainable bioenergy production across major commercial scales exceeding 1 million tons per year input capacity. Though challenges remain, the opportunities for lowered costs through economies of scale indicate the viability of very large bioenergy facilities playing an important long-term role in renewable energy portfolios.