A techno-economic analysis (TEA) of the integration of hydrothermal carbonization of waste biomass with an algal bioreactor is presented. Analyses of qualitative data from a two-m3 tubular photobioreactor constructed at Honda R&D Americas in Raymond, Ohio, USA, indicated that microalgal nutrient cost was a key economic challenge. The use of hydrothermal carbonization (HTC) of solid biowastes to provide lower cost nutrients was modeled. The TEA used results of previous work culturing microalgae in HTC process water, along with other data from the Honda algal bioreactor. Assumption for the scope of the analysis included capture of all carbon emissions from the Honda Marysville Auto Plant in Marysville, Ohio and application of a small onsite power plant using HTC solids to provide electricity and additional CO2 for the bioreactor system. Results indicated that HTC integration could decrease total operating costs of the bioreactor system by 17% and carbon capture costs by 11%. Additionally, results indicated the HTC system could contribute nearly 50% of key cost inputs (C, P, N and electricity) and increase EROI from 8.05 to 13.5.