Big green ideas

1. Biochar

In a nutshell: A way of trapping carbon with “green coal”.

The clever bit: Any biomass waste – from wood to peanut shells – releases carbon as it decomposes. But it can be burned in a kiln by pyrolysis (an airless burning technique) to create biochar, also known by the soubriquet green coal. The biochar is then dug back into the ground in order to lock carbon into the soil following a system set out by ancient South American civilisations – which exposes the idea as nothing new. What is groundbreaking, however, is using it to mitigate our current predicament – ie, runaway greenhouse gas emissions. According to experts, billions of tonnes of carbon could potentially be sequestered in the world’s soils, specifically from agriculture and forestry residual biomass. Biochar appears to lock carbon in for much longer than other forms or sequestration: a plant or tree will only sequester for 15 to 20 years, for example, whereas it seems reasonable to suggest that the biochar system will sequester for at least 100 years. Also, biochar just happens to anchor soil nutrients extremely well at a time when the planet’s soils have lost half of their carbon thanks to industrialised agriculture.

Light bulb rating: 5/5

2. Fertilising the ocean

In a nutshell: Dumping iron dust in the ocean to remove carbon.

The clever bit: It is acknowledged that the oceans are the planet’s biggest global sink, soaking up 2bn tonnes of carbon every year. Spreading iron dust on ocean waters can in fact trigger huge plankton blooms the size of a small city. The algae would then absorb carbon dioxide from the atmosphere, and when the algae dies, the whole lot sinks to the bottom of the ocean and is sequestered on the seabed. Proponents – notably Victor Smetacek, an oceanographer from the University of Bremen – suggest that it would take just five to 10 ocean-going ore carriers to deposit iron sulphate, a waste product from iron and titanium smelters, into the world’s oceans, and that the phytoplankton created would then remove 1 trillion kilograms of CO2 every year.

Light bulb rating: 3/5

3. Benign biofuels

In a nutshell: The biofuels it’s OK to like.

The clever bit: The idea was simple: burn plant-derived biofuels such as maize, sugar and corn in engines, then the CO2 released would be offset by the amount of gas absorbed by the plants when they grew. It appeared you could drive oil-free on green gold. Sadly this was a cruel mirage, and when we got close it became clear that the displacement impact of a biofuel boom would lead to the ploughing-up of virgin habitats, giant monocultures, land-rights disputes, and the truly terrible conundrum of whether to feed the world or power the rich world’s private – and expanding – car fleet. In a dramatic fall from grace, biofuels crashed and burned.

However, proponents of second-generation biofuels say it’s not the idea that is at fault, just the choice of biomass. This time around they advocate using the whole plant and converting waste materials such as cornstalks and leftover sugar-cane fibres into cellulosic ethanol that will then power our lives. This is reliant on a fledgling process: cracking or splitting cellulose into simple hydrocarbons – in effect breaking down complex chains and liberating sugars.

Light bulb rating: 3/5

4. Hydrogen cargo ships

In a nutshell: Emissions-free shipping.

The clever bit: To produce hydrogen-hybrid boats that could turn global shipping and freight from an emissions juggernaut into a zero-emissions glide across the oceans. The unlikely vehicle of revolution – which admittedly is some way off a transatlantic sortie right now – is a former British Waterways maintenance vessel, converted by Birmingham University, named the Ross Barlow. Believed to be the world’s first hydrogen-hybrid canal boat, the Ross Barlow’s system works by storing hydrogen in lithium hydride powder, which can be topped up when it has been exhausted.

It’s clever stuff because researchers have already overcome the two main hydrogen stumbling blocks that have dogged the automotive industry in particular. First, making hydrogen is one thing; storing it safely is another issue entirely. Unlike hydrogen cars, the system on the Ross Barlow barge means that there is no need to carry high-pressure gas or liquid on board – while there has always been a fear that hydrogen cars might, literally, go off like a bomb, the threat of potential explosions has been removed. And there’s another advantage: in cars, hydrogen has always proved to be too heavy, but the genius of the boat idea is that heavy hydrogen, in the form of lithium hydride powder, doesn’t matter – ships need ballast.

Light bulb rating: 4/5

5. Species relocation

In a nutshell: Giving under-threat species a second home.

The clever bit: You can see why the plight of the mustang, the romantic symbol of the American west, which is under threat from what has been termed “federal euthanasia”, caught the imagination of conservationists. The authorities decreed that the 33,000 mustang population roaming free on public lands across the west must be shot down to size (by losing 6,000). Critics contend that this is because they are in competition for food resources with cattle ranching. But the response – to move the mustangs to another part of the country entirely, to a privately funded refuge – has raised a few eyebrows. In many ways this goes against the grain of conservation practices (which are usually geared towards making the best of a bad job, as in the installation of conservation corridors for elephants that work around depleted areas or trouble spots). Pragmatists say it’s about cutting your losses and preventing extinction.

Light bulb rating: 2.5/5


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