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Synthetic Fuels

Page history last edited by Ulrich Bonne 12 years, 10 months ago

Generation of electricity and synthetic fuel from renewable energy

Ulrich Bonne, Kailua-Kona, Hawaii, ulrichbonne@msn.com

5 May 2011, rev. 6 July 2011


Abstract -- Assuming that we will phase-out importing oil in 10-20 years, we asked ourselves how much fuel to produce locally from clean electricity or bio-mass, and estimated the involved cost of alternatives.

It seems that a responsible conclusion we must draw and consider, as we forge a long-term energy (electricity and fuel) security and independence strategy, is that we should not only minimize the use of fossil fuel generators, but add as much clean and renewable electricity generation and synthetic fuel production capacity from wind, geo or solar energy as possible, and make it available preferentially, to:

  1. Directly operate electrical equipment during daytime availability of solar PV, geothermal and wind electricity as much as possible, so as to avoid incurring the 80-90% round-trip energy loss for storage in batteries
  2. Utilities and rate payers should make use of smart-grid signals (e.g. grid voltage level) to indicate grid-load, so that rate payer equipment can effectively adjust demand and benefit from low-cost, off-peak electricity supply to operate equipment, including PHEV and EV chargers
  3. Support the installation and operation of plants to produce synthetic fuels from water, carbon dioxide and electricity, because both ICV vehicle user/owner life cycle and imports costs are likely to be lower than for EVs or FCVs, as illustrated by Table 3.
  4. Design the synthetic fuel processing plants so that they can ramp production up and down to follow the availability and use of excess or “reserve” renewable electricity, rather than waste the wind, solar and/or geothermal energy during off-peak periods, as we are doing today

All of the above contribute to reducing fossil energy use and import costs as described in Table 3.

This has implications on how much synthetic fuel to produce. For Hawaii County, two to three 20 MGGE/y (synthetic or bio-) fuel plants should take care of Hawaii County’s foreseeable jet fuel needs***.  For Hawaii County to replace 50% of today’s ~140 MGGE/y of fuel for CVs, the added electricity generator investment would then be equivalent of (50/100)*140/4 = 17.5 MGGE/y, i.e. 1/4th of the fuel needed for CVs due to EVs 4x higher energy efficiency than CVs, or as little as 17.5e6 GGE/y*110000 Btu/GGE *1054 J/Btu/(3.6e6 J/kWh) /(8760 h/y) = 64 MW(average) in the next ~10-15 years. This time fits well with the needed ~8-10-year time to study, get permits, design, install and start-up the 20 MGGE/y plants, after which they would produce for 25-30 years. The produced fuels would be certified for use as aviation fuel, and for gasoline or diesel fuel for road engines.

*** Similarly, 150-200 MGGE/y may about meet the jet fuel needs for the State of Hawaii. On the long run, we assume that we may only have to replace half of the total amount of fossil fuels used today of ~750 MGGE/y because of the adoption of EVs and PHEVs may eliminate the need for the other half..

            Replacing the remaining 70 MGGE/y imported fossil fuel to Hawaii County with locally-produced synthetic fuel may require 300-500 MW(average) electrical power for the producer plants, depending on their overall 40-70 % conversion efficiency. Clearly, the capital investment in clean, renewable electricity generation to put EVs on the road is much lower (64 MW) than for ICVs, which additionally may need ~700 M$ to install the 70 MGGE/y synthetic-fuel producer plants. Both of these M$ numbers (and associated amortization and maintenance) strongly determine the exact price of synthetic fuels.

           To read the full paper, please click here.

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