# Biomethane: A Renewable Resource as Vehicle Fuel

^{*}

## Abstract

**:**

## 1. Introduction

_{2}eq/km, if CNG is composed also by 20% of biomethane (also called BIO-CNG (20%)). Instead, when pure biomethane (also called BIO-CNG (100%)) is used, WTW emissions are equal to 5 gCO

_{2}eq/km (Figure 2) [14].

^{3}injected into the grid and 0.73 €/m

^{3}as transportation fuel [22]. The discounted total cost for the organic fraction of municipal solid waste (ofmsw) substrate varies from 0.46–0.82 €/m

^{3}, while it is equal to 0.49–0.76 €/m

^{3}for a mixed substrate (maize and manure residues) [20].

^{3}/h if the biomethane is used for cogeneration and 250 m

^{3}/h for the other two final destinations. Instead, the financial feasibility of mixed substrate is verified only for a 500 m

^{3}/h plant if the biomethane is used as vehicle fuel [20].

- Plant size (50 m
^{3}/h, 100 m^{3}/h and 150 m^{3}/h). - Feedstock (ofmsw and a mixture of 30% maize and 70% manure residues on a weight basis).
- Subsidies (varying from 0.162 €/m
^{3}–0.487 €/m^{3}). - Selling price of biomethane (varying from 0.1384 €/m
^{3}–0.2397 €/m^{3}).

## 2. Materials and Methods

^{3}. In fact, one CIC corresponds to 0.837 t of biomethane, which is equivalent to 1231 m

^{3}of CH

_{4}. This conversion is obtained considering that 1 m

^{3}CH

_{4}= 0.68 kg under normal conditions (standard temperature of 273.15 K and pressure of 101.325 kPa).

^{3}/h plants, and the results underline that transport costs become more relevant than maintenance and overhead costs when a 1000 m

^{3}/h plant is considered for a mixed substrate [20].

$\mathrm{NPV}={\displaystyle \sum}_{\mathrm{t}=0}^{n}\left({\mathrm{I}}_{\mathrm{t}}-{\mathrm{O}}_{\mathrm{t}}\right)/{\left(1+\mathrm{r}\right)}^{\mathrm{t}}$ | (1) | |

$\sum}_{\mathrm{t}=0}^{\mathrm{DPBT}}\left({\mathrm{I}}_{\mathrm{t}}-{\mathrm{O}}_{\mathrm{t}}\right)/{\left(1+\mathrm{r}\right)}^{\mathrm{t}}=0$ | (2) | |

${\mathrm{Q}}_{\mathrm{biogas}}^{\mathrm{nom}}={\mathrm{S}}_{\mathrm{biogas}}{*\mathrm{n}}_{\mathrm{oh}}{*\text{\%}\mathrm{CH}}_{4}$ | (3) | |

${\mathrm{Q}}_{\mathrm{feedstock}}={\mathrm{Q}}_{\mathrm{biogas}}^{\mathrm{nom}}/\left({\mathrm{p}}_{\mathrm{b}}^{\mathrm{u}}*\left(\text{\%}\mathrm{vs}/\mathrm{ts}\right)*\left(\text{\%}\mathrm{ts}/\left(\mathrm{ww}+\mathrm{ts}\right)\right)\right)$ | (4) | |

${\mathrm{Q}}_{\mathrm{biogas}}={\mathrm{Q}}_{\mathrm{biogas}}^{\mathrm{nom}}*\left(1-{\mathrm{l}}_{\mathrm{bs}}\right)$ | (5) | |

${\mathrm{Q}}_{\mathrm{biomethane}}^{\mathrm{nom}}={\mathrm{S}}_{\mathrm{biomethane}}{*\mathrm{n}}_{\mathrm{oh}}$ | (6) | |

${\mathrm{Q}}_{\mathrm{biomethane}}={\mathrm{Q}}_{\mathrm{biogas}}*\left({\text{\%}\mathrm{CH}}_{4}\right)*\left(1-{\mathrm{l}}_{\mathrm{us}}\right)$ | (7) | |

${\mathrm{I}}_{\mathrm{t}}={\mathrm{R}}_{\mathrm{t}}^{\mathrm{subsidies}}+{\mathrm{R}}_{\mathrm{t}}^{\mathrm{selling}}+{\mathrm{R}}_{\mathrm{t}}^{\mathrm{ofmsw}}$ | (8) | |

${\mathrm{R}}_{\mathrm{t}}^{\mathrm{subsidies}}={\mathrm{Q}}_{\mathrm{biomethane}}{*\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}{*\mathrm{c}}_{\mathrm{c}}$ | $\forall $t = 0…n | (9) |

${\mathrm{R}}_{\mathrm{t}}^{\mathrm{selling}}={\mathrm{Q}}_{\mathrm{biomethane}}{*\mathrm{p}}_{\mathrm{sng}}^{*}{\text{}\mathrm{with}\text{}\mathrm{p}}_{\mathrm{sng}}^{*}=0.95{*\mathrm{p}}_{\mathrm{sng}}$ | $\forall $t = 0…n | (10) |

${\mathrm{R}}_{\mathrm{t}}^{\mathrm{ofmsw}}={\mathrm{Q}}_{\mathrm{ofmsw}}*\left({\mathrm{R}}_{\mathrm{gross},\mathrm{t}}^{\mathrm{ofmsw}}-{\mathrm{C}}_{\mathrm{t}}^{\mathrm{ofmsw}}\right)$ | $\forall $t = 0…n | (11) |

${0}_{\mathrm{t}}={\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{1\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{1\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{3\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{3\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{l},\mathrm{t}}+{\mathrm{C}}_{\mathrm{s},\mathrm{t}}+{\mathrm{C}}_{\mathrm{ts},\mathrm{t}}+{\mathrm{C}}_{\mathrm{mo},\mathrm{t}}^{1\xb0\mathrm{s}}+$ | (12) | |

$\hspace{1em}+{\mathrm{C}}_{\mathrm{df},\mathrm{t}}^{1\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{1\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{i},\mathrm{t}}^{1\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{mo},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{df},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{i},\mathrm{t}}^{2\xb0\mathrm{s}}+{\mathrm{C}}_{\mathrm{o},\mathrm{t}}^{\mathrm{dis}}+{\mathrm{C}}_{\mathrm{o},\mathrm{t}}^{\mathrm{com}}+{\mathrm{C}}_{\mathrm{tax},\mathrm{t}}$ | ||

${\mathrm{C}}_{\mathrm{inv}}^{1\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},1\xb0\mathrm{s}}{*\mathrm{S}}_{\mathrm{biogas}}$ | (13) | |

${\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{1\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{1\xb0\mathrm{s}}/{\mathrm{n}}_{\mathrm{debt}}$ | $\forall $t = 0…n_{debt}−1 | (14) |

${\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{1\xb0\mathrm{s}}=\text{}\left({\mathrm{C}}_{\mathrm{inv}}^{1\xb0\mathrm{s}}-{\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{1\xb0\mathrm{s}}\right){*\mathrm{r}}_{\mathrm{d}}$ | $\forall $t = 0…n_{debt}−1 | (15) |

${\mathrm{C}}_{\mathrm{inv}}^{2\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},2\xb0\mathrm{s}}{*\mathrm{S}}_{\mathrm{biomethane}}$ | (16) | |

${\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{2\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{2\xb0\mathrm{s}}/{\mathrm{n}}_{\mathrm{debt}}$ | $\forall $t = 0…n_{debt}−1 | (17) |

${\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{2\xb0\mathrm{s}}=\text{}\left({\mathrm{C}}_{\mathrm{inv}}^{2\xb0\mathrm{s}}-{\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{2\xb0\mathrm{s}}\right){*\mathrm{r}}_{\mathrm{d}}$ | $\forall $t = 0…n_{debt}−1 | (18) |

${\mathrm{C}}_{\mathrm{inv}}^{3\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{\mathrm{dis}}+{\mathrm{C}}_{\mathrm{inv}}^{\mathrm{com}}$ | (19) | |

${\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{3\xb0\mathrm{s}}={\mathrm{C}}_{\mathrm{inv}}^{3\xb0\mathrm{s}}/{\mathrm{n}}_{\mathrm{debt}}$ | $\forall $t = 0…n_{debt}−1 | (20) |

${\mathrm{C}}_{\mathrm{lis},\mathrm{t}}^{3\xb0\mathrm{s}}=\text{}\left({\mathrm{C}}_{\mathrm{inv}}^{3\xb0\mathrm{s}}-{\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{3\xb0\mathrm{s}}\right){*\mathrm{r}}_{\mathrm{d}}$ | $\forall $t = 0…n_{debt}−1 | (21) |

${\mathrm{C}}_{\mathrm{l},\mathrm{t}}={\mathrm{C}}_{\mathrm{l}}^{\mathrm{u},\mathrm{a}}{*\mathrm{n}}_{\mathrm{op}}$ | $\forall $t = 0…n | (22) |

${\mathrm{C}}_{\mathrm{s},\mathrm{t}}={\mathrm{C}}_{\mathrm{s}}^{\mathrm{u}}{*\mathrm{Q}}_{\mathrm{feedstock}}$ | $\forall $t = 0…n | (23) |

${\mathrm{C}}_{\mathrm{ts},\mathrm{t}}={\mathrm{C}}_{\mathrm{ts}}^{\mathrm{u}}{*\mathrm{Q}}_{\mathrm{feedstock}}$ | $\forall $t = 0…n | (24) |

${\mathrm{C}}_{\mathrm{mo},\mathrm{t}}^{1\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{mo}}^{1\xb0\mathrm{s}}{*\mathrm{C}}_{\mathrm{inv}}^{1\xb0\mathrm{s}}$ | $\forall $t = 0…n | (25) |

${\mathrm{C}}_{\mathrm{df},\mathrm{t}}^{1\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{df}}{*\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{1\xb0\mathrm{s}}$ | $\forall $t = 0…n | (26) |

${\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{1\xb0\mathrm{s}}={\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},1\xb0\mathrm{s}}{*\mathrm{Q}}_{\mathrm{biogas}}{*\mathrm{p}}_{\mathrm{e}}$ | $\forall $t = 0…n | (27) |

${\mathrm{C}}_{\mathrm{i},\mathrm{t}}^{1\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{i}}{*\mathrm{C}}_{\mathrm{inv}}^{1\xb0\mathrm{s}}$ | $\forall $t = 0…n | (28) |

${\mathrm{C}}_{\mathrm{mo},\mathrm{t}}^{2\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{mo}}^{2\xb0\mathrm{s}}{*\mathrm{C}}_{\mathrm{inv}}^{2\xb0\mathrm{s}}$ | $\forall $t = 0…n | (29) |

${\mathrm{C}}_{\mathrm{df},\mathrm{t}}^{2\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{df}}{*\mathrm{C}}_{\mathrm{lcs},\mathrm{t}}^{2\xb0\mathrm{s}}$ | $\forall $t = 0…n | (30) |

${\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{2\xb0\mathrm{s}}={\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},2\xb0\mathrm{s}}{*\mathrm{Q}}_{\mathrm{biogas}}{*\mathrm{p}}_{\mathrm{e}}$ | $\forall $t = 0…n | (31) |

${\mathrm{C}}_{\mathrm{i},\mathrm{t}}^{2\xb0\mathrm{s}}={\mathrm{p}}_{\mathrm{i}}{*\mathrm{C}}_{\mathrm{inv}}^{2\xb0\mathrm{s}}$ | $\forall $t = 0…n | (32) |

${\mathrm{C}}_{\mathrm{o},1}^{\mathrm{dis}}={\mathrm{C}}_{\mathrm{o}}^{\mathrm{dis}}$ with ${\mathrm{C}}_{\mathrm{o},\mathrm{t}+1}^{\mathrm{dis}}={\mathrm{C}}_{\mathrm{o},\mathrm{t}}^{\mathrm{dis}}*\left(1+\mathrm{inf}\right)$ | $\forall $t = 0…n | (33) |

${\mathrm{C}}_{\mathrm{o},1}^{\mathrm{com}}={\mathrm{C}}_{\mathrm{o}}^{\mathrm{com}}$ with ${\mathrm{C}}_{\mathrm{o},\mathrm{t}+1}^{\mathrm{com}}={\mathrm{C}}_{\mathrm{o},\mathrm{t}}^{\mathrm{com}}*\left(1+\mathrm{inf}\right)$ | $\forall $t = 0…n | (34) |

${\mathrm{C}}_{\mathrm{tax},\mathrm{t}}={\mathrm{p}}_{\mathrm{tax}}^{\mathrm{unit}}*\mathrm{ebt}$ | $\forall $t = 0…n | (35) |

- plant size, in which three values are analyzed: 50 m
^{3}/h, 100 m^{3}/h and 150 m^{3}/h. - feedstock used, in which two typologies are considered: ofmsw and a mixture with 30% maize and 70% manure residues on a weight basis.
- unitary subsidy, in which ten values are considered (Figure 3), varying from 0.162 €/m
^{3}–0.481 €/m^{3}. - selling price of biomethane, in which three values are considered (Figure 4), varying from 0.1384 €/m
^{3}–0.2397 €/m^{3}.

## 3. Results

- The 50 m
^{3}/h plant is always unprofitable. - The 100 m
^{3}/h plant is profitable in ten scenarios; positive NPV varies from 3.48 k€/(m^{3}/h)–29.73 k€/(m^{3}/h), and DPBT ranges from 1–3 years. Starting from a value of CIC equal to 500 € the profitability is verified for all prices of selling of biomethane, while with a CIC of 450 €, only with a price of selling equal to 0.2397 €/m^{3}. - The 150 m
^{3}/h plant is profitable in eighteen scenarios; positive NPV varies from 1.72 k€/(m^{3}/h)–44.12 k€/(m^{3}/h) and DPBT ranges from 1–4 years. Starting from a value of CIC equal to 400 €, the profitability is verified for all prices of selling of biomethane, while with a CIC of 375 €, that is the supposed value by the new decree (see Section 2), the plant is profitable in the Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ and Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ scenarios. Finally, NPV is positive also with a value of CIC of 350 € and ${\mathrm{p}}_{\mathrm{sng}}^{*}$ of 0.2397 €/m^{3}.

^{3}/h is the profitable minimum plant size in the baseline scenario, and also the 100 m

^{3}/h plant has NPV > 0 in alternative scenarios with an increase of incentive (${\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}$ equal to 0.41 €/m

^{3}) or a decrease of the maintenance and overhead cost of biogas production (${\mathrm{p}}_{\mathrm{mo}}^{1\xb0\mathrm{s}}$ equal to 15%) [20]. Results obtained in Table 2 and Table 3 define that the 150 m

^{3}/h plant is basically profitable, because CIC = 375 € is the more probable value. The analysis of several scenarios underlines that profits can be very relevant, but there also significant economic losses in some case studies.

- The 50 m
^{3}/h plant is always unprofitable. - The 100 m
^{3}/h plant is always unprofitable. - The 150 m
^{3}/h plant is profitable when a CIC equal to 600 € is present for all prices of selling of biomethane and in the case study with CIC = 550 € and ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.2397 €/m^{3}. Positive NPV varies from 0.47 k€/(m^{3}/h)–10.49 k€/(m^{3}/h), and DPBT ranges from 2–5 years.

^{3}/h as the minimum plant size in terms of profitability considering a baseline scenario. Furthermore, the 250 m

^{3}/h plant has NPV > 0 when there is an increase of incentive (${\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}$ equal to 0.41 €/m

^{3}) or a decrease of transport cost of the substrate (${\mathrm{C}}_{\mathrm{ts}}^{\mathrm{u}}$ equal to 1 €/t) [20]. Table 4 and Table 5 highlight that the probability of positive NPV with mixed substrate is very low; in fact, CIC equal to 550 € or 600 € is not tracked in the current market.

## 4. Discussion and Conclusions

^{3}of methane, two alternative scenarios were considered according to Section 1:

- A mixture composed of 20% biomethane and 80% methane (BIO-CNG (20%).
- Pure biomethane (BIO-CNG (100%).

^{3}/y when BIO-CNG (20%) is considered, obtained by the product between the number of NGVs and the annual NGV’s consumption. The reduction of GHG linked to this choice is 360 ktCO

_{2}eq per year considering the unitary reduction of 24 gCO

_{2}eq/km defined in Section 1 and hypothesizing that an NGV travels 15,000 km per year. Nine hundred fifty thousand NGVs powered by BIO-CNG (20%) save 6840 ktCO

_{2}eq compared to those powered by fossil fuel during 20 years (Table 6).

^{3}) and a use of 209 million m

^{3}/y is hypothesized, the amount of subsidies is equal to 64 million €/y.

^{3}/h plant, while one with mixed substrate can be obtained starting with a 250 m

^{3}/h plant in the scenario with a low cost of the transport of substrates. Alternatively, economic opportunities are provided by the incentive scheme when the producer of biomethane is also the distributor of methane. In this case, another corrective coefficient is recognized, and the pump price to the consumer is certainly higher than the price of selling of biomethane examined in this work. The excessive volatility of CICs influences in a negative way the investments in this sector, and consequently, new policy measures must be made to reduce this uncertainty.

## Author Contributions

## Conflicts of Interest

## Nomenclature

Symbol | Definition | Symbol | Definition |

1°s | biogas production | ${\mathrm{l}}_{\mathrm{us}}$ | losses in the upgrading system |

2°s | upgrading | n | lifetime of investment |

3°s | compression and distribution | ${\mathrm{n}}_{\mathrm{debt}}$ | period of loan |

cc | corrective coefficient | ${\mathrm{n}}_{\mathrm{oh}}$ | number of operating hours |

${\mathrm{C}}_{\mathrm{df}}^{1\xb0\mathrm{s}}$ | depreciation fund (1°s) | ${\mathrm{n}}_{\mathrm{op}}$ | number of operators |

${\mathrm{C}}_{\mathrm{df},\mathrm{t}}^{2\xb0\mathrm{s}}$ | depreciation fund (2°s) | ${\mathrm{n}}_{\mathrm{s}}$ | period of subsidies |

${\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{1\xb0\mathrm{s}}$ | electricity cost (1°s) | ${\mathrm{O}}_{\mathrm{t}}$ | discounted cash outflows |

${\mathrm{C}}_{\mathrm{e},\mathrm{t}}^{2\xb0\mathrm{s}}$ | electricity cost (2°s) | ${\mathrm{p}}_{\mathrm{b}}^{\mathrm{u}}$ | potential of biogas per unit of vs |

${\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},1\xb0\mathrm{s}}$ | unitary electricity consumption(1°s) | ${\mathrm{p}}_{\mathrm{df}}$ | % of depreciation fund |

${\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},2\xb0\mathrm{s}}$ | unitary electricity consumption(2°s) | ${\mathrm{p}}_{\mathrm{e}}$ | unitary price of electricity |

${\mathrm{C}}_{\mathrm{i}}^{1\xb0\mathrm{s}}$ | insurance cost (1°s) | ${\mathrm{p}}_{\mathrm{i}}$ | % of insurance cost |

${\mathrm{C}}_{\mathrm{i},\mathrm{t}}^{2\xb0\mathrm{s}}$ | insurance cost (2°s) | ${\mathrm{p}}_{\mathrm{mo}}^{1\xb0\mathrm{s}}$ | % of maintenance and overhead cost (1°s) |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{com}}$ | investment cost (compression) | ${\mathrm{p}}_{\mathrm{mo}}^{2\xb0\mathrm{s}}$ | % of maintenance and overhead cost (2°s) |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{dis}}$ | investment cost (distribution) | ${\mathrm{p}}_{\mathrm{sng}}$ | price of natural gas |

${\mathrm{C}}_{\mathrm{l}}$ | labor cost | ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | selling price of biomethane |

${\mathrm{C}}_{\mathrm{l}}^{\mathrm{u},\mathrm{a}}$ | unitary labor cost | ${\mathrm{p}}_{\mathrm{tax}}^{\mathrm{unit}}$ | % of taxes cost |

${\mathrm{C}}_{\mathrm{lcs}}$ | loan capital share cost | ${\mathrm{R}}_{\mathrm{t}}^{\mathrm{ofmsw}}$ | revenues by treatment of ofmsw |

${\mathrm{C}}_{\mathrm{lis}}$ | loan interest share cost | ${\mathrm{R}}_{\mathrm{gross},\mathrm{t}}^{\mathrm{ofmsw}}$ | gross revenues by ofmsw |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},1\xb0\mathrm{s}}$ | unitary investment cost (1°s) | ${\mathrm{R}}_{\mathrm{t}}^{\mathrm{selling}}$ | revenues by selling of biomethane |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},2\xb0\mathrm{s}}$ | unitary investment cost (2°s) | ${\mathrm{R}}_{\mathrm{t}}^{\mathrm{subsidies}}$ | revenues by subsidies |

${\mathrm{C}}_{\mathrm{mo}}^{1\xb0\mathrm{s}}$ | maintenance and overhead cost (1°s) | ${\mathrm{Q}}_{\mathrm{feedstock}}$ | quantity of feedstock |

${\mathrm{C}}_{\mathrm{mo}}^{2\xb0\mathrm{s}}$ | maintenance and overhead cost (2°s) | ${\mathrm{Q}}_{\mathrm{biogas}}$ | quantity of biogas |

${\mathrm{C}}_{\mathrm{o}}^{\mathrm{com}}$ | operative cost (compression) | ${\mathrm{Q}}_{\mathrm{biogas}}^{\mathrm{nom}}$ | nominal quantity of biogas |

${\mathrm{C}}_{\mathrm{o}}^{\mathrm{dis}}$ | operative cost (distribution) | ${\mathrm{Q}}_{\mathrm{biomethane}}$ | quantity of biomethane |

${\mathrm{C}}_{\mathrm{s}}$ | substrate cost | ${\mathrm{Q}}_{\mathrm{biomethane}}^{\mathrm{nom}}$ | nominal quantity of biomethane |

${\mathrm{C}}_{\mathrm{s}}^{\mathrm{u}}$ | unitary substrate cost | ${\mathrm{Q}}_{\mathrm{ofmsw}}$ | quantity of msw |

${\mathrm{C}}_{\mathrm{t}}^{\mathrm{ofmsw}}$ | cost ofmsw | r | opportunity cost |

${\mathrm{C}}_{\mathrm{tax}}$ | taxes cost | ${\mathrm{r}}_{\mathrm{d}}$ | interest rate on loan |

${\mathrm{C}}_{\mathrm{ts}}$ | transport cost of substrates | ${\mathrm{S}}_{\mathrm{biogas}}$ | plant size (biogas) |

${\mathrm{C}}_{\mathrm{ts}}^{\mathrm{u}}$ | unitary transport cost of substrate | ${\mathrm{S}}_{\mathrm{biomethane}}$ | plant size (biomethane) |

ebt | earnings before taxes | t | time of the cash flow |

${\mathrm{I}}_{\mathrm{t}}$ | discounted cash inflows | ts | total solids |

${\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}$ | unitary subsidy | vs | volatile solids |

inf | rate of inflation | ww | wet weight |

${\mathrm{l}}_{\mathrm{bs}}$ | losses in the biogas system | %CH_{4} | percentage of methane |

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**Figure 1.**Number of upgraded plants worldwide in 2015 [6].

**Figure 3.**Certificates of Emission of Biofuel in Consumption expressed in ${\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}$. Adapted by [25].

**Figure 4.**Selling price of biomethane expressed in ${\mathrm{p}}_{\mathrm{sng}}^{*}$. Adapted by [25].

**Figure 5.**Share of renewable energy [34]. GFEC, Gross Final Energy Consumption.

Variable | Value | Reference |
---|---|---|

${\mathrm{c}}_{\mathrm{c}}$ | 1.7 ^{a}; 2 ^{b} | [25] |

${\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},1\xb0\mathrm{s}}$ | 0.13 kWh/m^{3} | [27] |

${\mathrm{c}}_{\mathrm{e}}^{\mathrm{u},2\xb0\mathrm{s}}$ | 0.29 kWh/m^{3} | [26] |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{com}}$ | 53,000 € | [29] |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{dis}}$ | 237,500 € | [30] |

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},1\xb0\mathrm{s}}$ | 5100 €/kW ^{a,i}; 4800 €/kW ^{a,ii}; 4500 €/kW ^{a,iii} | [20] |

5300 €/kW ^{b,i}; 5000 €/kW ^{b,ii}; 5300 €/kW ^{b,iii} | ||

${\mathrm{C}}_{\mathrm{inv}}^{\mathrm{u},2\xb0\mathrm{s}}$ | 6300 €/(m^{3}/h) ^{i}; 5800 €/(m^{3}/h) ^{ii}; 5300 €/(m^{3}/h) ^{iii} | [20] |

${\mathrm{C}}_{\mathrm{l}}^{\mathrm{u},\mathrm{a}}$ | 25,000 €/y | [20] |

${\mathrm{C}}_{\mathrm{o}}^{\mathrm{com}}$ | 47,000 €/y | [29] |

${\mathrm{C}}_{\mathrm{o}}^{\mathrm{dis}}$ | 20,000 €/y | [30] |

${\mathrm{C}}_{\mathrm{s}}^{\mathrm{u}}$ | 10 €/t ^{c}; 0 € ^{b,d} | [27] |

${\mathrm{C}}_{\mathrm{t}}^{\mathrm{ofmsw}}$ | 49 €/t | [24] |

${\mathrm{C}}_{\mathrm{ts}}^{\mathrm{u}}$ | 2 €/t | [31] |

${\mathrm{i}}_{\mathrm{cic}}^{\mathrm{u}}$ | Table 2 | [25] |

inf | 2% | [20] |

${\mathrm{l}}_{\mathrm{bs}}$ | 6% | [30] |

${\mathrm{l}}_{\mathrm{us}}$ | 1.5% | [30] |

N | 20 y | [24] |

${\mathrm{n}}_{\mathrm{debt}}$ | 15 y | [24] |

${\mathrm{n}}_{\mathrm{oh}}$ | 8000 h | [24] |

${\mathrm{n}}_{\mathrm{op}}$ | 4 | [24] |

${\mathrm{n}}_{\mathrm{s}}$ | 20 y | [24] |

${\mathrm{p}}_{\mathrm{b}}^{\mathrm{u}}$ | 350 ^{d}–500 ^{b}—650 ^{c} m^{3}biogas/t(vs) | [20] |

${\mathrm{p}}_{\mathrm{df}}$ | 20% | [20] |

${\mathrm{p}}_{\mathrm{e}}$ | 0.13 €/kWh | [20] |

${\mathrm{p}}_{\mathrm{i}}$ | 1% | [20] |

${\mathrm{p}}_{\mathrm{mo}}^{1\xb0\mathrm{s}}$ | 10% ^{a}; 20% ^{b} | [26] |

${\mathrm{p}}_{\mathrm{mo}}^{2\xb0\mathrm{s}}$ | 10% | [24] |

${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Table 3 | |

${\mathrm{p}}_{\mathrm{tax}}^{\mathrm{unit}}$ | 27.5% | [24] |

${\mathrm{Q}}_{\mathrm{ofmsw}}$ | 5952 t ^{i}; 11,905 t ^{ii}; 17,857 t ^{iii} | [20] |

${\mathrm{Q}}_{\mathrm{maize}}$ | 1163 t ^{i}; 2363 t ^{ii}; 3525 t ^{iii} | [20] |

${\mathrm{Q}}_{\mathrm{manure}\text{}\mathrm{residues}}$ | 19,579 t ^{i}; 39,789 t ^{ii}; 59,368 t ^{iii} | [20] |

r | 5% | [20] |

${\mathrm{r}}_{\mathrm{d}}$ | 3% | [24] |

${\mathrm{R}}_{\mathrm{gross},\mathrm{t}}^{\mathrm{ofmsw}}$ | 70 €/t | [24] |

S_{biogas} | 155 kW ^{a,i}; 315 kW ^{a,ii}; 470 kW ^{a,iii}; | [20] |

150 kW ^{b,i}; 300 kW ^{b,ii}; 450 kW ^{b,iii} | ||

S_{biomethane} | 50 (m^{3}/h) ^{i}; 100 (m^{3}/h) ^{ii}; 150 (m^{3}/h) ^{iii} | [20] |

${\text{\%}\mathrm{CH}}_{4}$ | 57% ^{a}; 60% ^{b} | [24] |

%ts/(ww + ts) | 9.5% ^{d}; 27% ^{b}; 30.8% ^{c} | [32] |

%vs/ts | 80% ^{d}; 89.6% ^{b}; 95.9% ^{c} | [32] |

^{3}/h; ii = 100 m

^{3}/h; iii = 150 m

^{3}/h.

50 m^{3}/h Plant | 100 m^{3}/h Plant | 150 m^{3}/h Plant | |||||||
---|---|---|---|---|---|---|---|---|---|

CIC | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ |

200 € | −3897 | −3729 | −3392 | −4517 | −4180 | −3507 | −4618 | −4112 | −3103 |

250 € | −3489 | −3320 | −2984 | −3699 | −3362 | −2689 | −3391 | −2886 | −1876 |

300 € | −3080 | −2911 | −2575 | −2882 | −2545 | −1872 | −2165 | −1660 | −650 |

350 € | −2681 | −2513 | −2176 | −2084 | −1747 | −1074 | −969 | −463 | 546 |

375 € | −2472 | −2303 | −1967 | −1666 | −1329 | −656 | −341 | 165 | 1174 |

400 € | −2272 | −2104 | −1767 | −1267 | −930 | −257 | 258 | 763 | 1772 |

450 € | −1864 | −1695 | −1359 | −449 | −112 | 561 | 1484 | 1989 | 2999 |

500 € | −1465 | −1296 | −960 | 348 | 685 | 1358 | 2680 | 3186 | 4195 |

550 € | −1056 | −888 | −551 | 1166 | 1503 | 2176 | 3906 | 4412 | 5421 |

600 € | −657 | −489 | −152 | 1963 | 2300 | 2973 | 5103 | 5608 | 6618 |

^{3}; Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.1722 €/m

^{3}; Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.2397 €/m

^{3}. Profitable cases are shown in bold.

50 m^{3}/h Plant | 100 m^{3}/h Plant | 150 m^{3}/h Plant | |||||||
---|---|---|---|---|---|---|---|---|---|

CIC | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ |

200 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

250 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

300 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

350 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | 3 |

375 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | 4 | 2 |

400 € | >20 | >20 | >20 | >20 | >20 | >20 | 4 | 3 | 2 |

450 € | >20 | >20 | >20 | >20 | >20 | 3 | 2 | 2 | 1 |

500 € | >20 | >20 | >20 | 3 | 2 | 2 | 2 | 1 | 1 |

550 € | >20 | >20 | >20 | 2 | 2 | 1 | 1 | 1 | 1 |

600 € | >20 | >20 | >20 | 2 | 1 | 1 | 1 | 1 | 1 |

^{3}; Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.1722 €/m

^{3}; Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.2397 €/m

^{3}. Profitable cases are shown in bold.

50 m^{3}/h Plant | 100 m^{3}/h Plant | 150 m^{3}/h Plant | |||||||
---|---|---|---|---|---|---|---|---|---|

CIC | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ |

200 € | −5170 | −5004 | −4674 | −7233 | −6897 | −6226 | −8128 | −7626 | −6625 |

250 € | −4829 | −4663 | −4333 | −6540 | −6204 | −5533 | −7094 | −6592 | −5591 |

300 € | −4488 | −4322 | −3992 | −5847 | −5511 | −4840 | −6060 | −5558 | −4556 |

350 € | −4155 | −3989 | −3659 | −5171 | −4835 | −4164 | −5051 | −4549 | −3548 |

375 € | −3980 | −3815 | −3484 | −4816 | −4480 | −3809 | −4521 | −4019 | −3018 |

400 € | −3814 | −3648 | −3318 | −4478 | −4142 | −3470 | −4016 | −3515 | −2513 |

450 € | −3473 | −3307 | −2977 | −3785 | −3449 | −2777 | −2982 | −2481 | −1479 |

500 € | −3140 | −2974 | −2644 | −3108 | −2772 | −2101 | −1973 | −1472 | −470 |

550 € | −2799 | −2633 | −2303 | −2415 | −2079 | −1408 | −939 | −437 | 564 |

600 € | −2466 | −2301 | −1970 | −1739 | −1403 | −732 | 70 | 571 | 1573 |

^{3}; Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.1722 €/m

^{3}; Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.2397 €/m

^{3}. Profitable cases are shown in bold.

50 m^{3}/h Plant | 100 m^{3}/h Plant | 150 m^{3}/h Plant | |||||||
---|---|---|---|---|---|---|---|---|---|

CIC | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Min ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ | Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ |

200 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

250 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

300 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

350 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

375 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

400 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

450 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

500 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 |

550 € | >20 | >20 | >20 | >20 | >20 | >20 | >20 | >20 | 3 |

600 € | >20 | >20 | >20 | >20 | >20 | >20 | 5 | 3 | 2 |

^{3}; Avg ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.1722 €/m

^{3}; Max ${\mathrm{p}}_{\mathrm{sng}}^{*}$ = 0.2397 €/m

^{3}. Profitable cases are shown in bold.

**Table 6.**Environmental benefits of the biomethane used in the transport sector. NGV, Natural Gas Vehicle.

Scenario BIO-CNG (20%) | Scenario BIO-CNG (100%) | |
---|---|---|

Biomethane demand (million m^{3}/y) | 209 | 1045 |

Reduction of GHG (gCO_{2}eq/km) | 24 | 119 |

1 NGV | ||

Reduction of GHG (kgCO_{2}eq/y) | 360 | 1785 |

Reduction of GHG (tCO_{2}eq) | 7.2 | 35.7 |

950,000 NGVs | ||

Reduction of GHG (tCO_{2}eq/y) | 342,000 | 1,695,750 |

Reduction of GHG (tCO_{2}eq) | 6,840,000 | 33,915,000 |

CIC (€) | Scenario BIO-CNG (20%) | Scenario BIO-CNG (100%) |
---|---|---|

0.162 | 34 | 169 |

0.203 | 42 | 212 |

0.244 | 51 | 255 |

0.284 | 59 | 297 |

0.305 | 64 | 319 |

0.325 | 68 | 340 |

0.366 | 76 | 382 |

0.406 | 85 | 424 |

0.447 | 93 | 467 |

0.487 | 102 | 509 |

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Cucchiella, F.; D'Adamo, I.; Gastaldi, M. Biomethane: A Renewable Resource as Vehicle Fuel. *Resources* **2017**, *6*, 58.
https://doi.org/10.3390/resources6040058

**AMA Style**

Cucchiella F, D'Adamo I, Gastaldi M. Biomethane: A Renewable Resource as Vehicle Fuel. *Resources*. 2017; 6(4):58.
https://doi.org/10.3390/resources6040058

**Chicago/Turabian Style**

Cucchiella, Federica, Idiano D'Adamo, and Massimo Gastaldi. 2017. "Biomethane: A Renewable Resource as Vehicle Fuel" *Resources* 6, no. 4: 58.
https://doi.org/10.3390/resources6040058