Climate dreaming 205 That the level of negative emissions in some models is comparable in size with the remaining carbon budget means that as much carbon must somehow be extracted as may still be emitted! The feasibility and moral acceptability of heavy reliance on NETs are clearly major, but relatively little discussed, issues. 2 A PROMISE THAT MAY NOT BE FULFILLED: IS BECCS LIKELY TO WORK ON A LARGE ENOUGH SCALE? Most NETs are not yet proven at scale, and serious obstacles of various types stand in the way of scaling any of them up to a level at which they could produce the required global impact. To rely on them as a matter of policy is to gamble that something will turn up to solve all the problems confronted by at least one of them. Most NETs are hypothetical solutions, not confirmed solutions. Smith and his collaborators have examined the respective strengths and weaknesses of several leading contenders among the NETs in their impressive study, and I will merely mention briefly a very few illustrative worries here, starting with some concerns specific to the NET invoked in the most scenarios, BECCS: bio-energy (BE) combined with carbon capture and storage (CCS). An alternative NET currently being seriously explored is direct air capture (DAC), but DAC makes large energy demands. The energy requirements in 2100 for amine DAC, for example, to remove a sufficient amount of carbon (3.3 Gt Ceq yr-1) to make a difference would be ‘equivalent to 29% of total global energy use in 2013 (540 EJ yr-1), and a significant proportion of total energy demand in 2100’.4 By contrast, BECCS would have the great merit that it actually produces net energy – this is the bio-energy part – while removing carbon from the atmosphere in two steps, through the photosynthesis involved in the initial growth of the biological material that is the feedstock for the combustion, and through the CCS that captures most of the emissions from the combustion of biomass that produces the energy. But BECCS has high land-use intensity. To remove the same significant amount of carbon (3.3 Gt Ceq yr-1) looked at in the case of DAC, the feedstocks would need, depending on exactly which crops were grown, ‘a land area of approximately 380–700 Mha in 2100’,5 which Anderson and Peters later note is ‘one to two times the area of India’!6 And BECCS also makes large demands on water, which Smith estimates for 2100 as ‘~3% of the freshwater currently appropriated for human use’!7 If less of the land is irrigated, water demand goes down, but land demand goes up; if more of the land is irrigated, land demand goes down, but water demand goes up. The question that the calculations by Smith makes obvious is: given the likely global population in 2100 and the consequent likely food demand, how are operators of BECCS going to find the equivalents of one or two Indias’ worth of land and of 3% of the current human use of water?8 Washington Post, 13 October, <https://www.washingtonpost.com/news/energy-environment/ wp/2016/10/13/were-placing-far-too-much-hope-in-pulling-carbon-dioxide-out-of-the-airscientists-warn/?utm_term=.8d48f85a3e60> accessed 29 April 2017. 4. Smith et al. (n 2) at 47. 5. Ibid at 46. 6. Anderson and Peters (n 3) at 183. 7. Smith et al. (n 2) at 47. 8. It could only be done through demand management – largely by a move away from livestock products in diets toward plant-based foods – and cutting current levels of food waste: B Bajželj, © 2017 The Author Journal compilation © 2017 Edward Elgar Publishing Ltd