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Elephant Grass

What is Elephant Grass

Elephant Grass is the common name for Miscanthus x Giganteus, which is a sterile hybrid of Miscanthus Sinensis and Miscanthus Sacchariflorus.

It is a Spring planted non-invasive, perennial 2nd generation Bio-energy grass that grows up to 3 metres tall. 

Once established it is harvested annually in the Spring when the crop has completed its annual growth cycle. Unlike other crops, there is no need for any chemicals to support growth.

The crop grows naturally by resourcing most of its own nutrients intensifying Biodiversity by providing a safe habitat for wildlife and reducing our over reliance on woodland.  It can be grown on marginal land which compliments traditional food production.   

As a high yield crop, it is a serious contributor to the bioeconomy combining raw materials such as biocarbon, lignin, cellulose, and ethanol. It contributes positively to the carbon sink from year two (carbon is stored in the soil and cane), a process that lasts, taken from data collected, for more than 20 years without the need to re-plant.

This makes Miscanthus vital in maintaining soil stability and facilitating the long-term sequestration (carbon capture) and storage of atmospheric carbon dioxide (CO2) or other forms of carbon to mitigate or defer global warming.

Carbon is sequestered by the soil on average of 1 tonne per hectare per annum (about the size of an international football pitch) in the soil.

The cane is 48% carbon (4.8 tonnes to the hectare @ 10 tonne yield) and can be used for energy for carbon neutral solutions or locked up in other products such as construction materials, animal bedding, textiles, and plastics alternatives. (see our projects page).

The Effects on Climate Change

The Climate Change Committee in its latest Land Use Report (January 2020) has made supportive statements with regard to bio-energy crops (biomass).

Bioenergy Crops: Expanding the growing of energy crops by around 23,000 hectares each year would deliver 2 million tonnes CO2e emissions savings in the land sector and an extra 11 million tonnes CO2e from the harvested biomass (e.g. when used with *CCS)

Bioenergy crops are faster growing than new woodlands and are needed as part of the overall mix of land-based measures!

*CCS - Carbon Capture & Storage

Why is Elephant Grass a serious contributor to combating Climate Change?

Current methods of carbon sequestration are mainly based around tree planting and forestry. However, given that we are now in a “climate emergency”, an interim solution to the time taken for trees to grow, mature and sequent carbon is needed. Miscanthus can fill that gap and offer an enhancement to forestry which prevents deforestation (through provision of raw materials) and produces results in a much faster time frame as the examples below illustrate.                  

1)  Newly planted trees take more than 20 years on average before they start becoming carbon neutral. This assumes that they reach maturity before being cut down as raw material for construction and other processes, burnt in forest fires or left to rot. Miscanthus contributes to the carbon sink from year two.

2)  The water consumption of trees can have a major effect on our precious water supplies. Research shows that some reforestation schemes have caused rivers to dry up. Miscanthus, because of its root system uses little water, it can also be planted on flood plains.             

3)  Returning land from forestry to food production is problematic because of stump and root removal depleting the soils nutrients.  Miscanthus is a grass and can be removed by applying a simple grass weed chemical it also improves the soil quality meaning new crops can be planted with ease.

4) It is difficult to calculate the exact amount of CO2 sequestered into the soil by a tree per year due to complex biological and climatic variables involved in tree growth, however an average estimate indicates a single tree sequesters up to 20kg of CO2 per year. It is estimated that a forest composed of Maple, Birch and Beech trees sequesters about 1.97 tons of CO2 per hectare annually after 25 years. Compare this to Miscanthus at a rate of 1 tonne per hectare annually from year two.

How we calculate our carbon capture

Calculation of the carbon capture of Elephant Grass is the easy part - we know that 48% of the plant is carbon (assume 10t per annum yield of cane per hectare) so this equates to 17.61t of CO2e annually per hectare. Add in the soil (average figures) of 3.67t of CO2e and this comes to a total of 21.28t of CO2e per year.

For the cane, this figure is at 100% utilisation, although it will never be that as you need to deduct for harvesting and processing. The captured cane CO2 remains captured until the products that it's used for are scrapped at some point in the future unless reused.

It's important to note here that these factors are the same for any plant material that is used within the economy, indeed if a tree is used for furniture only a small part of the carbon is stored in the furniture as a major portion will have gone into waste / energy used (think shaping, planeing etc).

A single plant over 20 years (although we have seen ground where the plant is 25 years old and still yielding well) will capture 26.60kg of CO2e.

Please revisit this page for further updates on the Life Cycle Analysis data. There are a number of references with regard to emmissions and carbon capture and a large number differ. If you feel that there are discrepancies with the data we have used, please get in touch. We want to make this as realistic as possible.

Potential car miles offset

To get to our potential miles offset figure, we looked at the average kg of CO2e emmitted per mile of transport which comes to 0.175313kg per mile. Please find our references here

Now we divide the total of the CO2e captured by the number of plants selected with the emmission per mile figure to provide the number of miles covered by the capture.

We then divided by 2 (to cover the fact that we are 'offsetting' energy costs too).

Potential energy offset

To get to our potential energy offset figure, we looked at the average kg of CO2e emmitted per person using gas and electricity. Please find our references:

Number of UK population: 68,000,000 (reference)

Number of UK households: 28,000,000 (reference)

Number of UK households: 28,000,000 (reference) This gives an avg of 2.43 people per household

Avg Electricty kWh used per household: 4,521 (reference) Divided by the avg people per household gives a figure of 1861.59 per person

Avg Gas kWh used per household: 12,052 (reference) Divided by the avg people per household gives a figure of 4962.59 per person

From the references supplied above, we see that the combined kg of CO2e emmissions for both energy sources come to 1,389.68kg per person per annum.

Now we divide the total of the CO2e captured by the number of plants selected with the emmission per person figure to provide the number of kWh covered by the capture.

We then divided by 2 (to cover the fact that we are 'offsetting' travel by car costs too).

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