Solar Power vs. Solar Fuels, for CO2 mitigation

The proper assessment of decarbonisation strategies needs to consider their actual effectiveness, relative to each other, and in the widest context of Nature's Carbon cycle - global as it is.

The sun drives the winds for turbines and emits photons for solar panels, for each to generate power.  They can offset the CO2 otherwise produced from fossil fuel generation, after accounting for the CO2 output in their manufacture and maintenance, and for the back-up power and storage systems needed to balance their intermittency in supply.

 

However these ‘renewables’ (what is it that’s renewable? ) do not feature in the Carbon cycle of Nature; they cannot be zero carbon, nor redress the elevated levels of CO2 in the atmosphere. They can offset the rate of rise, but not sequester the carbon to bring about a fall.

Nature  can and does, through the single process of photosynthesis central to all life on Earth, with sunlight converting atmospheric CO2 to biomass.  Bio-synthesis process technologies can use biomass as feedstocks to produce ‘solar fuels’, as an integral part of the Carbon cycle.  Biofuels have a carbon:hydrogen ratio of ~1:3 compared with ~2:3 for the feedstock biomass.  A proportion of this 'excess' carbon can be sequestered directly for burial during the conversion, so 'Carbon Capture & Storage' is a natural part of the fuel production process - much simpler than the current CCS proposals, where the CO2 has to be stripped from the overall exhaust gas after fuel combustion, for pressurised storage.

Nature is already in the business of carbon capture; it’s the only practical way to reverse the GHG problem at effective scale.  With Nature’s Carbon cycle an example of ‘chemical looping’, it offers an alternative perspective on hydrogen as a practical energy medium: chemically bound with carbon as the carrier it comes in many biofuel forms that are produced naturally, easy to handle and clean in combustion, after which the carbon goes back round the photosynthesis loop…. The perceived attraction of hydrogen is as a zero carbon fuel - this way it still is, as net zero, when seen in the wider bio-cycle.

 

The biofuel route makes possible a ‘negative carbon’ energy supply system - nothing else does - by ‘paying’ Nature to do the job through production of truly renewable fuels, which can only promote further greening of the planet and thereby atmospheric CO2 reduction.  Lignin and cellulose are infinitely renewable as an energy storage medium, unlike lithium and cobalt et al for the electrification route.  By example there's already an abundance of waste biomass arisings from forestry and crop harvests, which need to be cleaned up as routine for replanting.  This disposal cost would turn to a 'co-crop' feedstock value for biofuels manufacture, before considering dedicated energy crops, and the shorter the growth/cropping cycle the faster is this chemical looping and carbon sequestration process.  

So it follows that the more this fuel supply is used the faster will the atmosphere be repaired, by removing carbon and returning it to the ground.