Hype and reality

Hype and reality

by Martin Livermore
article from Monday 5, February, 2018

IT'S NOT OFTEN that I get an opportunity to quote Private Eye, but here goes. In a column by ‘Old Sparky’ (issue 1462), under the headline ‘Real food for thought’ is a critique of the biomethane industry in general and Good Energy (a big player in the sector) in particular. To quote: “But, as with other bio-energy, biomethane is not always genuinely sustainable. And Good Energy, the big seller of so-called green gas, is disingenuous in what it tells its customers.”

The piece goes on to explain that the anaerobic digestion process is not terribly efficient, that bulky feedstuff needs to be trucked to the digesters and that CO2 makes up 39% of the output, alongside methane. Nevertheless, if it is waste biomass being processed, then there is a good argument for turning it into usable fuel. This is indeed what Good Energy promotes, telling customers that the biomethane is made from “waste, manure, sewage, decaying food…All the organic matter we source comes from food waste.”

Except it doesn’t. Anaerobic digestion (AD) can quite legally use non-waste (ie, edible food crops) for up to half of its feedstock. The company’s major biomethane supplier, based in Somerset, already uses about one-third food crops (beet in particular) in the biomass feed and seems set to increase it. The irony is that, as more attention is put on reducing waste along the food chain, so more food crops get processed in anaerobic digesters, and biomethane makes less and less sense.

It’s not difficult to find other examples of the message not living up to the reality. Bioethanol seems like a particularly egregious one. One of the key climate change policies implemented in both the EU and USA mandates that a certain proportion of biofuel has to be included in all petrol and diesel. In the case of petrol, this is currently bioethanol, made by fermenting starch from food crops.

In America, this means maize, and a large part of the US maize crop has been sold for this purpose in recent years. At one point, this contributed to high maize prices at a time of generally raised food prices and even led to protests in parts of Central America, where corn-based tortillas are a staple food. In 2016, the last year for which figures are available, about one third of the US maize crop was converted to biofuel.

The situation is similar for biodiesel. In this case, a relatively small amount of used cooking oil is reprocessed, but the main feedstocks are edible oils, generally rape in Europe and palm oil on a wider international basis. As well as diverting grains and oils from use as food, the expansion of oil palm cultivation is controversial because of the loss of remaining areas of Asian rainforest. But while biofuel production can disrupt food markets, constraints on biomass availability mean that it can only ever hope to replace a minor proportion of conventional motor fuel.

A third very clear example of the reality being less palatable than the public message is the use of biomass to generate electricity. Small quantities of pollarded willow and miscanthus grass are grown in the UK and elsewhere as energy crops, but the bulk of biomass used in Europe in this sector is in the form of wood pellets imported from America. The Drax Group generates about 7% of the UK’s total electricity from its vast, formerly coal-fired plant in East Yorkshire. Two thirds of this comes from biomass, almost entirely wood pellets, and a large proportion of these are shipped from the USA. The group’s own American operations supply 15% of this total, and the intention is to increase this proportion.

While the message is that Drax is producing clean, green energy, the reality is a little different. As a large and relatively modern coal-fired facility, the site was an efficient and reliable generator of electricity, but the introduction of carbon pricing meant its economic days were numbered. The result is the conversion (not yet complete) to a site burning biomass instead of coal.

For this, Drax receives public subsidies that make it a profitable business, because it ticks the right box in terms of emissions reduction. However, wood pellets are not only less energy dense than coal (and hence more costly to transport) but actually produce about 40% more carbon dioxide per unit of electricity. The only reason they are regarded as a better option is that the CO2 emitted is nominally reabsorbed over a period of time by newly-planted trees.

While this is technically correct, it seems somewhat misleading to describe electricity from biomass as clean and green when it is actually making a greater contribution to global warming in the short to medium term than the very coal it displaces. Since we are told repeated of the urgent need to reduce emissions as soon as possible, the active encouragement of biomass use has a certain Alice in Wonderland quality.

In a completely rational world, it would seem to make more sense to continue burning coal, while planting trees to fix the carbon dioxide emitted, which would be considerably lower than the amount emitted by burning wood. The point is that only certain ways of cutting emissions are regarded as good. This is why EU targets have included mandatory targets for use of renewable energy and, in the case of motor transport, biofuels. Policy in this area is ideological rather than rational.

One unintended consequence of the complex set of rules designed to achieve the goal – defining the pathway rather than simply the target – has been the replacement of gas-fired generators by coal-fired ones in Germany, the very opposite of what we might expect. One that is perhaps even more perverse is the plan to reduce France’s dependence on clean, reliable nuclear power by expanding renewable energy capacity. Just how this can be done without increasing emissions is not yet clear.

The message is simple: when it comes to choosing ‘green’ energy, caveat emptor

Martin Livermore writes for the Scientific Alliance, which advocates the use of rational scientific knowledge in the development of public policy. To subscribe to his regular newsletter please use this link.

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