The delivered cost of energy as electricity from grid systems varies significantly, through complex cross-pricing and subsidy mechanisms by region, customer sector and time of day consumption. For the UK example an indicative spread is around 14 to 24 p/kWh (plus standing charges), this for a grid currently accommodating around 35% renewables generation, with an overall carbon factor ~180 g/kWh.  The further costs to attain a stable ‘zero carbon’ supply based primarily on renewables is the big question, as yet with no clear answer.

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The delivered cost of energy as fuel is also distorted, in this case through the significant taxes and duties generally applied, but around 3 to 4 p/kWh is the current economic marker for conventional petroleum fuel options.  Their carbon factor range of 180 to 260 g/kWh compares with grid electricity at its current renewables level, when producing power and heating together as in the IUS.  For lower carbon, the first generation biofuels are around 6 to 8 p/kWh, but the real scope for supply lies in the ‘advanced biofuel’ technologies emerging in the last decade, based on Nature's constant and widely available supply of biomass residues for feedstock.

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Using ligno-cellulosic ethanol as the example, current indicators suggest around 8 to10 p/kWh is feasible (IEA 2020) with developments along the learning curve: higher than current fuels, but lower than for electricity. And also with a directly verifiable carbon factor from individual source to use (cf. grid electricity), with two components: not just the fossil energy consumption it displaces but with carbon sequestration as part of the production process. Should carbon be clearly monetised, this adds a further premium to the value of a biofuel strategy, along with an incentive to make good use of biomass waste rather than leaving it to rot down: anaerobic CH4 emission has a GWP 27 times worse than CO2. 

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The IUS concept itself can also improve the economics of biofuelling:

• In the IUS application the fuel netback value equates to the full set of utility service tariffs it displaces at the point of use, not just the grid electricity; significantly higher in total than the current benchmark of petroleum fuel prices used by biofuel developers.

• The costs of feedstock and delivery to centralised biofuel process plants is a major factor, accounting for a third to a half of the projected costs cited above. Transportable IUS facilities could support on-site modular fuel production systems, with the process taken to, and moved around, the feedstock sources as they come available.