It is forecasted that by 2050 the worldwide energy consumption will rise by roughly 26% to 725 Exajoules a year with this there will come a demand for new and greater energy production capabilities. Around 84% of the current consumption is sourced by traditional fossil fuels. While these resources are finite and predicted to be depleted by 2060 if new deposits are not found, the most pressing issue surrounding them is sustainability and the environment.
Gas, oil, and coal are accountable for roughly 94% of all global CO2 emissions every year. The climate change caused by this is leading to an increasingly less hospitable world. The global weather is becoming more severe, with higher temperatures worsening; storms, heat waves, floods, and droughts. It is clear that the current approach is not working and needs revising.
Bioenergy refers to heat energy and gas generated from organic matter known as biomass. It can be utilised by a variety of different methods and technologies to generate the energy that the world needs to keep on turning. There is an estimated 880 gigatons of carbon (Gt C) of biomass distributed among all the kingdoms of life. With bioenergy being produced from plants and animals alive today, it is a far easier resource to replenish than fossil fuels and could be seen as a substantially more sustainable approach. This essay will explore this topic and determine how sustainable bioenergy truly is.
Bioenergy is a broad term that encompasses a wide variety of technologies and processes, because of this it is inherently difficult to define how sustainable it is. There will be differing pros and cons for each technology. To make this essay more feasible and offer any actual valid insight the scope will be narrowed to focus on 3 differing areas. These are Wood pellets, Anaerobic digestion (AD) and Algae biofuel, selected as they have the potential to replace each of coal, natural gas, and oil.
Biomass pellets are made of either freshly cut timber or by-products of wood processing reconstituted from sawdust, shavings, and offcuts (Luxury wood, 2021). The wood is dried and pelletized and then can be used for any typical combustion processes e.g. replacing coal in a power plant.
Anaerobic digestion is a process in which organic matter is broken down, in the absence of oxygen, to produce biogas. This biogas can then be used as a renewable natural gas. The process also has the added benefit of producing a valuable by-product, a digestate that can be used as an organic fertiliser.
Algae is a unique plant it has fast growth rates and a substantially higher yield of lipids than conventional oil crops. These lipids are then used in the production of biodiesel which itself has all the practical applications of any regular liquid fuel. Algae has an added bonus of being able to grow on typically non-arable land that is unsuitable for food crops, another area it surpasses typical oil crops.
The production and supply of fossil fuels is dominated by only a handful of the world’s countries, this gives them immense power over other nations without their own fuel source and leaves them dependant. Bioenergy can offer energy security for these smaller nations meaning current and future energy needs can be met irrespective of economic or political instability.
Not only will producing biofuels provide energy security but with it comes an economic boost. In 2018 The EU spent €331 billion importing fossil fuels and this figure keeps rising. This high dependence on imported fuels can be mitigated if they begin to produce and utilise biofuels. This has 2 key benefits, of course the import cost will begin to drop, but the production of these biofuels will also create jobs.
The scale of the jobs created will increase year on year as the production of biofuels is ramped up to eventually match what is currently supplied by fossil fuels. In order to initiate this, it is likely that some government subsidies will be required but if the programme is successful the economic boon from biofuels is undeniable.
The environmental standpoint on different biofuels is less clear cut, this will be discussed in more detail later, but it is certainly not without its benefits. The harmful effects of fossil fuels on the environment are undeniable and biofuels would definitely help to mitigate this. The reduction of burning fossil fuels and releasing carbon that has been trapped for millions of years is vital. Using biofuels will achieve this reduction in carbon dioxide emissions. However, if done incorrectly the environmental effects of the biofuels can actually be more damaging.
Biofuels have the ability to offer decentralised grid networks for energy and power needs. This is less import for nations with an already substantial electrical transmission and oil and gas pipe network but could stop further damage being done in nations without this infrastructure already in place. An example of this Keystone XL pipeline in North America. It would connect Canadian oil fields to refineries on the gulf coast of Texas. This pipeline will undoubtedly damage numerous ecosystems and have a severe environmental cost to build. With a decentralised bioenergy system biooil could be produced exactly where it was needed removing the need for this project entirely.
The PESTLE analysis outlined some clear pros and cons with using wood pellets as a biofuel. One of the key areas why wood pellets seems like such an attractive option is the fact that existing coal fired power stations can be converted relatively simply to use this fuel. The DRAX power station in the UK has been undergoing a conversion to wood pellet biomass since 2012 and the total cost of upgrading its existing units has been around £700 million. The cost of conversion is only getting cheaper and the fourth DRAX generating unit conversion costing £30 million. It is estimated for a newly built coal fired power station with a capacity of 600MW the cost would be somewhere in the region of $2 billion. The DRAX power station has a capacity of 3,906MW, this means for just under half the cost of a new power station, the original one can be converted to biomass fed whist retaining over 6 times the energy capacity. Clearly this is an economically sustainable approach.
Issues arise with using wood pellet biomass when more than just the financials are considered. Ideally, the wood pellets would be sourced solely from waste wood from industry however there simply isn’t enough waste wood to make this approach viable.
The next most sustainable approach would be to use specifically grown trees that are harvested and replanted in quick succession. While this might be happening on some scale, it is happening in conjunction with the logging of old wood forests causing further environmental damage. The destruction of these forests is not only damaging to the climate but also destroys ecosystems causing flooding, habitat loss and species extinction.
Putting the sourcing of wood issue aside, still leaves the problem of the pollutants and greenhouse gasses of combustion. The burning of wood pellets still releases carbon dioxide, volatile organic compounds, and particulate matter into the environment. A lot of the carbon emissions from the burning of wood pellets is often omitted from the record as it is deemed to be removed by the growth cycle of the trees. However, if the trees are not replanted or it is old growth forest used then the emissions remain almost on par with that of just burning coal.
It is clear from this that using wood pellets on such a large scale is just not sustainably feasible. However it still presents as an attractive option for smaller scale facilities. If they were used to heat individual homes in areas with large wood waste from production, then wood pellets certainly are a sustainable technology.
AD seems to show a substantially more clear-cut picture with regard to sustainability. From an economic standpoint It offers a multitude of positives. Firstly companies and city councils will pay to have their municipal waste removed, this waste can be converted into biogas and fertiliser, which can then be sold for a further profit. This a system which will help generate a circular economy with less waste, vital for a sustainable system. AD plants are expensive to set up and run and plants in the UK have to adhere to strict governmental guidelines requiring a highly skilled team to monitor and adjust the system constantly. This is of course a steep cost but will ultimately be negated by the triple income stream.
A current issue with the deployment of AD is the size and scalability of it. Currently in the UK there are an estimated 640 AD facilities, and a lot of these facilities are small scale working on farms. The largest of the facilities has the ability to supply biogas to around 10,000 homes. There are roughly 29 million homes in the UK alone, so anaerobic digestion currently comes nowhere near being able to meet this amount. If viewed as simply a means to produce biogas, AD clearly isn’t a viable solution, but viewed as a way to reduce waste going to landfill then it is definitely a far more sustainable approach than the current solution.
The environmental side of anaerobic digestion is where it really comes into its own as a real solution. British agriculture greenhouse gas emissions were 45.6 million tonnes of CO2 equivalent in 2017, it is estimated that AD can reduce this value by 66%. AD can also reduce the odour of waste, this reduction in pollution and improvement of air quality offers a greater quality of life to anything living near any waste processing facilities. Finally it is known that AD can remove phosphorus and other metals from the wastewater supply that will eventually make it back into nature. Excess phosphorus can cause plants to grow poorly and die and seriously hamper already fragile ecosystems.
Anaerobic digestion is growing in popularity and prevalence around the world despite the lack of financial support. Its unique ability to provide rural communities with a renewable natural gas supply is unparalleled. Even in poorer parts of the world a less refined cruder version of the process can be done. The output gas is not as clean as it could be but still a useable resource for cooking or heating needs.
Economically, algae are presently the least sustainably viable of the 3 technologies reviewed. Currently, it suffers from an array of problems which are stopping any large-scale deployment. Algae requires large amounts of resources, water, and fertiliser, to be able to grow. It also requires a specific growing environment with temperature and carbon dioxide levels having to be monitored and regulated. These factors combined with the menial public and private sector investments in the technology these days present serious hurdles which need to be overcame. It is because of these specific challenges and requirements that in 2013 ExxonMobil’s former CEO stated it could take 25 years to develop a commercially viable product.
One of algae’s strongest areas is that it can be grown on non-arable land. An issue surrounding more common biofuels is that due to different government subsidies farmers are switching over to growing energy crops instead of feed crops. It was estimated in Europe that between 2011 and 2020 an area the size of Ireland was converted to agriculture use to meet biofuel demand. In a time where it is estimated that 821 million people globally do not have enough food it is socially irresponsible to use this land for fuel and not to feed these people.
Despite this algae still presents some serious environmental concerns. To make it a viable product it has been reasoned that it will require genetic modification. If this modified crop was to get out of its designated grow area into the wild it could pose a biological risk to that ecosystem. A hardy algae that is designed to multiply and survive in inhospitable conditions would pose a real threat to delicate natural environments as it could easily overpower any existing crops.
The analysis shows there is no ‘one size fits all’ answer to sustainability for bioenergy and must simply be taken on a case by case basis. For the case of wood pellets on a large scale like what is being undertaken at DRAX, it is clearly not sustainable. Depleting countless old growth forests on another continent and then processing them before transferring them across the ocean does not meet any definition of sustainability. However, these pellets, if produced by the correct means, could be used to heat individual homes or buildings, and does offer a sustainable option.
Anaerobic digestion is helping to generate a circular economy which is paramount to a sustainable world going forward. While it may not be the answer to completely replacing natural gas with biogas, it is a step in the right direction and offers an excellent improvement on the ways waste is currently dealt with.
Algae has a lot of potential as a biooil production crop and may help save farmland from being converted to produce non feed crops. However it will require substantial work and financial investment. If the algae production facilities are managed incorrectly the genetically modified crop cause serious ecological issues so it must be managed carefully. Bioenergy in all its forms does not offer a perfect solution to meeting energy demands but it does offer, a more sustainable than what is done presently, step in the right direction.