Last month, the United Nations released a report detailing how humanity can limit global temperature rises to no more than 1.5C. To achieve this, scientists say we not only need to drastically reduce carbon emissions, but also take out the carbon dioxide we’ve already emitted into the atmosphere. Almost all of the UN’s scientific scenarios that ensure the future of human civilisation itself are staked on this ‘negative emissions’ theory. But the route to negative emissions many governments are banking on has fundamental flaws. It combines biomass – burning wood and other organic material for energy – with carbon capture and storage, a process known as BECCS for short. Biomass, without CCS, already accounts for around half of the European Union’s total ‘renewable’ energy consumption and is a key plank of the bloc’s plan to decarbonise energy. The BECCS theory is that as trees grow, they absorb carbon and – once burned – technology is used to capture and store the CO2 released. This results in more carbon being removed from the atmosphere than is emitted from the process of producing biomass energy. Simple? Let’s consider just how many trees we’re talking about. For BECCS to be commercially viable it would require a vast amount of fast-growing bioenergy crops. Much of the biomass feedstock is therefore likely to come from the global south, where tropical climates enable trees to grow much more quickly. But the scale of the land needed to achieve the negative emissions from BECCS assumed in almost all of the IPCC’s scenarios does not square with the land globally available. One scenario aiming to limit global warming to 1.5C would require bioenergy crops to be planted over an area almost two times the size of India.
Business Green 6th Nov 2018 read more »